High Rydberg states of helium hydride
Ketterle, W.; Messmer, H.; Walther, H. )
1989-12-15
High-lying Rydberg states (11{le}{ital n}{le}34) of helium hydride have been observed. They were produced by laser excitation of a fast molecular beam and detected by field ionization. Ionization potentials, quantum defects, and the binding energy of HeH{sup +} were determined. Pure rotational autoionization leads to break offs of the series. From missing lines it is concluded that {ital B} {sup 2}{Pi}(A{prime}) state decays by predissociation.
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}?) states allows a detailed study of the influence of the helium droplet on the SO splitting as function of the principal quantum number. Within the pseudo-diatomic picture the alkali-He_{N} system represents a diatomic molecule. The coupling of the Cs valence electrons spin and the orbital angular momentum with the intermolecular axis, which is defined by the connection between the droplet center and the alkali nucleus, depends on the strength of the atomic SO interaction. While the splitting of the 6^{2}P_{1/2}(^{2}?_{1/2}) and 6^{2}P_{3/2}(^{2}?_{3/2}) components has an atom-like character (Hund's case (c) coupling), the SO splitting of higher n states is lower than the atomic value (Hund's case (a) coupling). C. Callegari and W. E. Ernst, Helium Droplets as Nanocryostats for Molecular Spectroscopy - from the Vacuum Ultraviolet to the Microwave Regime, in: Handbook of High-Resolution Spectroscopy, eds. M. Quack and F. Merkt, John Wiley & Sons, Chichester, (2011) F. Lackner, G. Krois, M. Theisen, M. Koch, and W.E. Ernst, Phys. Chem. Chem. Phys., 13, 18781-18788 (2011) F. Lackner, G. Krois, and W.E. Ernst, J. Phys. Chem. Lett., 3, 1404-1408 (2012)
NASA Technical Reports Server (NTRS)
Au, C. K.
1989-01-01
The Breit correction only accounts for part of the transverse photon exchange correction in the calculation of the energy levels in helium Rydberg states. The remaining leading corrections are identified and each is expressed in an effective potential form. The relevance to the Casimir correction potential in various limits is also discussed.
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.
Quantum entanglement of helium atom in high-lying Rydberg states
NASA Astrophysics Data System (ADS)
Jiao, Li-Guang; Ho, Y. K.
2015-05-01
Quantum entanglement for identical particles in atomic systems and quantum dots has attracted considerable interest in recent years. With the successes of our group in accurately calculating the quantum entanglement (measured by von Neumann or the linear entropy) for the helium atom in ground and lower-lying excited states, we move on to the higher-lying Rydberg states and concentrate on the asymptotic behavior of the entanglement in loosely bound states. By applying the Lowdin's canonical orthogonalization method to the Slater-type orbital configuration-interaction basis sets, we have obtained quite accurate wave functions for the 1 sn s1Se with n = 1 to 15 and 2 sn s3Se states, with n = 2 to 15, and from which entanglement entropies for such states are quantified by calculating the occupation numbers of the respective one-electron reduced density matrix < i |?1| j > through a generalized eigenvalue problem. At the meeting, we will present our results and show the correlation between energies, effective quantum numbers, and entanglement for states in these Rydberg series. Work supported by the Ministry of Science and Technology of Taiwan.
Black-body induced ionization rate of Rydberg states in helium
NASA Astrophysics Data System (ADS)
Glukhov, I. L.; Ovsiannikov, V. D.
2007-06-01
The probabilities of photoionization by the black-body radiation (BBR) were calculated for singlet and triplet S-, P-, and D-Rydberg states of a neutral helium atom. The numerical values obtained on the basis of the Fues model potential for states with the principal quantum number n ranging from 8 to 45 were used to derive a formula which not only reproduces the asymptotical behavior of the ionization rate for n --> ? but also describes exactly its maximums. The n-independent constants in this formula are determined by a third order polynomial in powers of the absolute temperature with coefficients derived from the calculated data for the temperature range from 200 to 2000 K.
Thermal photoionization of Rydberg states in helium and alkali-metal atoms
NASA Astrophysics Data System (ADS)
Glukhov, I. L.; Ovsiannikov, V. D.
2009-04-01
Approximation formulae in the form of quadratic polynomials in combination with Planck's distribution are proposed for the thermal ionization rates of Rydberg states in helium and alkali atoms. The coefficients of the polynomials were determined by fitting the data for the rates calculated by integrating the photoionization cross sections obtained in the model potential approach for the S, P and D states with the principal quantum number ranging from n= 10 to n= 45, in product with Planck's frequency distribution for the flux of blackbody photons at temperatures from 100 K to 2000 K. Tables of the polynomial coefficients are presented for the atoms indicated. The deviations of the data given by the approximation formula from that of the straightforward integration of cross sections is less than 7% for states with n from 20 up to 55 in the temperature range from 70 K to about 1000 K, not exceeding 40-50% for states with n= 20-100 in the temperature range extending up to 10 000 K, thus providing rather simple and accurate estimates for experiments and for practical applications.
Buenermann, Oliver; Kornilov, Oleg; Neumark, Daniel M. [Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Department of Chemistry, University of California, Berkeley, California 94720 (United States); Haxton, Daniel J.; Gessner, Oliver [Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Leone, Stephen R. [Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Department of Chemistry, University of California, Berkeley, California 94720 (United States); Department of Physics, University of California, Berkeley, California 94720 (United States)
2012-12-07
The ejection dynamics of Rydberg atoms and molecular fragments from electronically excited helium nanodroplets are studied with time-resolved extreme ultraviolet ion imaging spectroscopy. At excitation energies of 23.6 {+-} 0.2 eV, Rydberg atoms in n= 3 and n= 4 states are ejected on different time scales and with significantly different kinetic energy distributions. Specifically, n= 3 Rydberg atoms are ejected with kinetic energies as high as 0.85 eV, but their appearance is delayed by approximately 200 fs. In contrast, n= 4 Rydberg atoms appear within the time resolution of the experiment with considerably lower kinetic energies. Major features in the Rydberg atom kinetic energy distributions for both principal quantum numbers can be described within a simple elastic scattering model of localized perturbed atomic Rydberg atoms that are expelled from the droplet due to their repulsive interaction with the surrounding helium bath. Time-dependent kinetic energy distributions of He{sub 2}{sup +} and He{sub 3}{sup +} ions are presented that support the formation of molecular ions in an indirect droplet ionization process and the ejection of neutral Rydberg dimers on a similar time scale as the n= 3 Rydberg atoms.
Dipolar Dephasing of Rydberg D -State Polaritons
NASA Astrophysics Data System (ADS)
Tresp, C.; Bienias, P.; Weber, S.; Gorniaczyk, H.; Mirgorodskiy, I.; Büchler, H. P.; Hofferberth, S.
2015-08-01
We experimentally study the effects of the anisotropic Rydberg interaction on D -state Rydberg polaritons slowly propagating through a cold atomic sample. We observe the interaction-induced dephasing of Rydberg polaritons at very low photon input rates into the medium. We develop a model combining the propagation of the two-photon wave function through our system with nonperturbative calculations of the anisotropic Rydberg interaction to show that the observed effect can be attributed to pairwise interaction of individual Rydberg polaritons at distances larger than the Rydberg blockade.
Ionization and excitation of hydrogen and helium Rydberg atoms by microwaves
Moorman, L.; Sauer, B.E.; Yoakum, S.; Koch, P.M. (Physics Department, State University of New York, Stony Brook, NY (USA)); Galvez, E.J. (Department of Physics and Astronomy, Colgate University, Hamilton, NY (USA)); van de Water, W.; van Leeuwen, K.A.H. (Physics Department, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (The Netherlands))
1990-04-01
We have used the interaction of hydrogen Rydberg atoms with microwave fields to study multiphoton ionization. The minimum number of photons absorbed in the experiments ranges from about 300 to only 15. A brief overview is given of the extensive theoretical work that is under development to explain experimental data, including various observed structures. Similarly we report on ionization of helium Rydberg atoms, qualitatively explained in terms of a static picture. Finally we show selective excitation of He triplet {ital s}-state to higher angular momentum states, via absorption of several photons from the field. Using the Floquet method a close analogy between the microwave problem and slow atomic collisions can be made. Sharp resonant structures in the spectra can be linked to individual avoided crossings of calculated Floquet quasi-energy curves. Our theory that exploits a separation of timescales explains very well the positions, depths, and shapes of the observed structures, but a discrepancy still remains concerning their widths.
Reactions of Rydberg states of molecular hydrogen
NASA Astrophysics Data System (ADS)
Pratt, S. T.; Dehmer, J. L.; Dehmer, P. M.; Chupka, W. A.
1994-07-01
The Rydberg state reaction H*2+H2?H+3+H+e- was studied by exciting the (X 2?+g)np,v=0,J Rydberg states with n=30-70 by double resonance excitation via the E,F 1?+g,v=0,J=1 level and by detecting the product ions or electrons. The results are consistent with the reaction occurring between the ion core of the Rydberg molecule and the ground state molecule, with the Rydberg electron acting as a spectator. Thus, these reactions can be used to provide information on the analogous ion-molecule reactions, and the possibility of using the Rydberg state reactions to study the rotational state dependence of the corresponding ion-molecule reactions is discussed.
Spectroscopy of nS, nP, and nD Rydberg series of Cs atoms on helium nanodroplets.
Lackner, F; Krois, G; Theisen, M; Koch, M; Ernst, W E
2011-11-14
The preparation of an artificial superatom consisting of a positive charge inside a superfluid helium nanodroplet and an electron in an orbital surrounding the droplet is of fundamental interest and represents an experimental challenge. In this work, nanodroplets of several thousand helium atoms are doped with single caesium (Cs) atoms. While on the droplet, the Cs valence electron is excited in two steps through an intermediate state into nS, nP, and nD states. The excitation is monitored by laser induced fluorescence or, for high principal quantum numbers, by resonant three-photon-ionization. On-droplet Rydberg excitations are resolved up to about n = 20. The energies are compared with those of free Cs atom Rydberg states and quantum defects as well as the on-droplet ionization threshold are derived. PMID:21789302
Leif Holmlid
2002-01-01
The recent experiments on processes in cold Rydberg gases produced by laser excitation have so far only a weak relation to Rydberg matter (RM) and its formation, despite some attempts to make such a connection. The problems of forming RM from cold Rydberg gases are severe and due to at least five obvious factors: the condensation energy, the non-circular states
Kaprálová-?ánská, Petra Ruth; mydke, Jan [J. Heyrovsky Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejkova 3, 182 23 Prague 8 (Czech Republic) [J. Heyrovsky Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejkova 3, 182 23 Prague 8 (Czech Republic); Department of Radiation and Chemical Physics, Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague 8 (Czech Republic); Civi, Svatopluk [J. Heyrovsky Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejkova 3, 182 23 Prague 8 (Czech Republic)] [J. Heyrovsky Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejkova 3, 182 23 Prague 8 (Czech Republic)
2013-09-14
Recently optimized exponentially tempered Gaussian basis sets [P. R. Kapralova-Zdanska and J. Smydke, J. Chem. Phys. 138, 024105 (2013)] are employed in quantitative simulations of helium absorption cross-sections and two-photon excitation yields of doubly excited resonances. Linearly polarized half-infinite and Gaussian laser pulses at wavelengths 3858 nm and large intensities up to 100 TW/cm{sup 2} are considered. The emphasis is laid on convergence of the results with respect to the quality of the Gaussian basis sets (typically limited by a number of partial waves, density, and spatial extent of the basis functions) as well as to the quality of the basis set of field-free states (typically limited by the maximum rotational quantum number and maximum excitation of the lower electron). Particular attention is paid to stability of the results with respect to varying complex scaling parameter. Moreover, the study of the dynamics is preceded by a thorough check of helium energies and oscillator strengths as they are obtained with the exponentially tempered Gaussian basis sets, being also compared with yet unpublished emission wavelengths measured in electric discharge experiments.
Fractional Quantum Hall States of Rydberg Polaritons
Mohammad F. Maghrebi; Norman Y. Yao; Mohammad Hafezi; Thomas Pohl; Ofer Firstenberg; Alexey V. Gorshkov
2014-11-24
We propose a scheme for realizing fractional quantum Hall states of light. In our scheme, photons of two polarizations are coupled to different atomic Rydberg states to form two flavors of Rydberg polaritons that behave as an effective spin. An array of optical cavity modes overlapping with the atomic cloud enables the realization of an effective spin-1/2 lattice. We show that the dipolar interaction between such polaritons, inherited from the Rydberg states, can be exploited to create a flat, topological band for a single spin-flip excitation. At half filling, this gives rise to a photonic (or polaritonic) fractional Chern insulator -- a lattice-based, fractional quantum Hall state of light.
Fractional Quantum Hall States of Rydberg Polaritons
Maghrebi, Mohammad F; Hafezi, Mohammad; Pohl, Thomas; Firstenberg, Ofer; Gorshkov, Alexey V
2014-01-01
We propose a scheme for realizing fractional quantum Hall states of light. In our scheme, photons of two polarizations are coupled to different atomic Rydberg states to form two flavors of Rydberg polaritons that behave as an effective spin. An array of optical cavity modes overlapping with the atomic cloud enables the realization of an effective spin-1/2 lattice. We show that the dipolar interaction between such polaritons, inherited from the Rydberg states, can be exploited to create a flat, topological band for a single spin-flip excitation. At half filling, this gives rise to a photonic (or polaritonic) fractional Chern insulator -- a lattice-based, fractional quantum Hall state of light.
Fractional quantum Hall states of Rydberg polaritons
NASA Astrophysics Data System (ADS)
Maghrebi, Mohammad F.; Yao, Norman Y.; Hafezi, Mohammad; Pohl, Thomas; Firstenberg, Ofer; Gorshkov, Alexey V.
2015-03-01
We propose a scheme for realizing fractional quantum Hall states of light. In our scheme, photons of two polarizations are coupled to different atomic Rydberg states to form two flavors of Rydberg polaritons that behave as an effective spin. An array of optical cavity modes overlapping with the atomic cloud enables the realization of an effective spin-1 /2 lattice. We show that the dipolar interaction between such polaritons, inherited from the Rydberg states, can be exploited to create a flat, topological band for a single spin-flip excitation. At half filling, this gives rise to a photonic (or polaritonic) fractional Chern insulatora lattice-based, fractional quantum Hall state of light.
Dipolar dephasing of Rydberg D-state polaritons
Tresp, Christoph; Weber, Sebastian; Gorniaczyk, Hannes; Mirgorodskiy, Ivan; Büchler, Hans Peter; Hofferberth, Sebastian
2015-01-01
We experimentally study the effects of the anisotropic Rydberg-interaction on $D$-state Rydberg polaritons slowly propagating through a cold atomic sample. In addition to the few-photon nonlinearity known from similar experiments with Rydberg $S$-states, we observe the interaction-induced dephasing of Rydberg polaritons at very low photon input rates into the medium. We develop a model combining the propagation of the two-photon wavefunction through our system with nonperturbative calculations of the anisotropic Rydberg-interaction to show that the observed effect can be attributed to pairwise interaction of individual Rydberg polaritons.
Dipolar dephasing of Rydberg D-state polaritons
Christoph Tresp; Przemyslaw Bienias; Sebastian Weber; Hannes Gorniaczyk; Ivan Mirgorodskiy; Hans Peter Büchler; Sebastian Hofferberth
2015-05-14
We experimentally study the effects of the anisotropic Rydberg-interaction on $D$-state Rydberg polaritons slowly propagating through a cold atomic sample. In addition to the few-photon nonlinearity known from similar experiments with Rydberg $S$-states, we observe the interaction-induced dephasing of Rydberg polaritons at very low photon input rates into the medium. We develop a model combining the propagation of the two-photon wavefunction through our system with nonperturbative calculations of the anisotropic Rydberg-interaction to show that the observed effect can be attributed to pairwise interaction of individual Rydberg polaritons.
Rydberg states via CPmmW spectroscopy
NASA Astrophysics Data System (ADS)
Zhou, Yan; Grimes, David; Field, Robert
2014-05-01
Rydberg-Rydberg transitions of Ca atoms are directly observed by chirped-pulse millimeter-wave spectroscopy, which is a form of broadband, high-resolution, free induction decay (FID) spectroscopy with accurate relative intensities. At moderate to high number densities (~106 cm-3), interactions between many Rydberg atoms are mediated by an AC electric field, absorbing and radiating cooperatively. A semiclassical model describes several significant time-domain and frequency-domain cooperative effects in two-level systems and ?-type three-level systems. Experimental evidence that supports this model will be discussed. A new experiment, employing the buffer gas cooling technique has been constructed and I expect to present preliminary results. In partically, the >100-fold increase in number density will permit study of ``pure electronic'' spectra of Rydberg molecules, such as BaF. We expect to produce 108 state selected core-nonpenetrating Rydberg molecules in a single pulse of a laser-laser-mm-wave excitation sequence.
Calculated photoexcitation spectra of positronium Rydberg states
NASA Astrophysics Data System (ADS)
Hogan, S. D.
2013-06-01
Calculations of the photoexcitation spectra of ortho-positronium Rydberg states with principal quantum numbers between 10 and 30 are presented. The effects of Doppler broadening and saturation of the corresponding electric-dipole transitions are studied, together with the role of static and motionally induced electric fields. This is done in the context of recent measurements reported by Cassidy [Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.108.043401 108, 043401 (2012)], and with regard to experiments involving the production of antihydrogen by charge-exchange between Rydberg positronium and cold antiprotons.
Electron capture form elliptical Rydberg states
Cornelius, K.R.; Olson, R.E. [Univ. of Missouri, Rolla, MO (United States); Wang, J.
1996-05-01
Recent experiments involving electron capture from elliptical Rydberg states have shown a strong correlation between the total cross sections and the eccentricity of the Rydberg state and the orientation of the electron orbit with respect to the incoming charged particle. In this study, the authors have used the classical trajectory Monte Carlo method to study collisions of H{sup +} on H(n = 4). The total cross sections are evaluated as a function of the eccentricity and the angle between the incoming ion and the plane of the electron`s orbit. These cross sections are calculated for reduced velocities of v/n = 1.0 to 2.0. The results are compared to the cross sections obtained using closed coupling calculations. In addition, the product n-state distributions are calculated and compared to existing values.
Rydberg Spectroscopy of Zeeman-Decelerated Beams of Metastable Helium Molecules
NASA Astrophysics Data System (ADS)
Jansen, Paul; Motsch, Michael; Sprecher, Daniel; Merkt, Frederic
2014-06-01
Having three and four electrons, respectively, He_2^+ and He_2 represent systems for which highly accurate ab-initio calculations might become feasible in the near future. With the goal of performing accurate measurements of the rovibrational energy-level structure of He_2^+ by Rydberg spectroscopy of He_2 and multichannel quantum-defect theory extrapolation techniques, we have produced samples of helium molecules in the a ^3?u^+ state in supersonic beams with velocities tunable down to 100 m/s by combining a cryogenic supersonic-beam source with a multistage Zeeman decelerator. The molecules are formed at an initial velocity of 500 m/s by striking a discharge in the pulsed expansion of helium gas from a reservoir kept at a cryogenic temperature of 10 K. Using rotationally-resolved PFI-ZEKE (pulsed-field-ionization zero-kinetic-energy) photoelectron spectroscopy, we have probed the rotational-state distribution of the molecules produced in the discharge and found vibrational levels up to ?" = 2 and rotational levels up to N"=21 to be populated. The molecular beam is coupled to a multistage Zeeman decelerator that employs pulsed inhomogeneous magnetic fields to further reduce the beam velocity. By measuring the quantum-state distribution of the decelerated sample using photoelectron and photoionization spectroscopy we observed no rotational or vibrational state-selectivity of the deceleration process, but found that one of the three spin-rotation components of the He_2 a ^3?u^+ rotational levels is eliminated. W.-C. Tung, M. Pavanello, L. Adamowicz, J. Chem. Phys. 136, 104309 (2012). D. Sprecher, J. Liu, T. Krähenmann, M. Schäfer, and F. Merkt, J. Chem. Phys. 140, 064304 (2014). M. Motsch, P. Jansen, J. A. Agner, H. Schmutz, and F. Merkt, arXiv:1401.7774. N. Vanhaecke, U. Meier, M. Andrist, B. H. Meier, and F. Merkt, Phys. Rev. A 75, 031402(R) (2007).
Microwave multiphoton ionization and excitation of helium Rydberg atoms
van de Water, W. (Physics Department, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (The Netherlands)); Yoakum, S. (Department of Physics, State University of New York at Stony Brook, Stony Brook, NY (USA)); van Leeuwen, T. (Physics Department, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (The Netherlands)); Sauer, B.E.; Moorman, L. (Department of Physics, State University of New York at Stony Brook, Stony Brook, NY (USA)); Galvez, E.J. (Department of Physics and Astronomy, Colgate University, Hamilton, NY (USA)); Mariani, D.R. (Schlumberger-Doll Research, Ridgefield, CT (USA)); Koch, P.M. (Department of Physics, State University of New York at Stony Brook, Stony Brook, NY (USA))
1990-07-01
We study experimentally and theoretically the detailed field-amplitude dependence of the multiphoton ionization and excitation probability of highly excited {ital n}{sub 0} {sup 3}{ital S} helium atoms in a 9.924-GHz linearly polarized microwave electric field. For ionization, with principal quantum numbers in the range {ital n}{sub 0}=25--32, we use a quasistatic analysis that employs integration of the time-dependent Schroedinger equation using basis states of the static field Hamiltonian. The calculated results are used to interpret the observed ionization threshold structure. For excitation, the results of {ital n}{sub 0} {sup 3}{ital S}{r arrow}{ital n}{sub 0} {sup 3}{ital L}, L{gt}2 excitation experiments are explained quantitatively and precisely using a theory of multiphoton resonances. We present maps of quasienergy levels that allow the study of the dynamics of the field-switching transients. These transient effects are analyzed along the lines of standard atomic collision theory and are shown to determine the shape of the observed resonances.
State-selective all-optical detection of Rydberg atoms
NASA Astrophysics Data System (ADS)
Karlewski, Florian; Mack, Markus; Grimmel, Jens; Sándor, Nóra; Fortágh, József
2015-04-01
We present an all-optical protocol for detecting population in a selected Rydberg state of alkali-metal atoms. The detection scheme is based on the interaction of an ensemble of ultracold atoms with two laser pulses: one weak probe pulse which is resonant with the transition between the ground state and the first excited state, and a pulse with high intensity which couples the first excited state to the selected Rydberg state. We show that by monitoring the absorption signal of the probe laser over time, one can deduce the initial population of the Rydberg state. Furthermore, it is shown thatfor suitable experimental conditionsthe dynamical absorption curve contains information on the initial coherence between the ground state and the selected Rydberg state. We present the results of a proof-of-principle measurement performed on a cold gas of 87Rb atoms. The method is expected to find application in quantum computing protocols based on Rydberg atoms.
State-selective all-optical detection of Rydberg atoms
Karlewski, Florian; Grimmel, Jens; Sándor, Nóra; Fortágh, and József
2015-01-01
We present an all-optical protocol for detecting population in a selected Rydberg state of alkali atoms. The detection scheme is based on the interaction of an ensemble of ultracold atoms with two laser pulses: one weak probe pulse which is resonant with the transition between the ground state and the first excited state, and a pulse with high intensity which couples the first excited state to the selected Rydberg state. We show that by monitoring the absorption signal of the probe laser over time, one can deduce the initial population of the Rydberg state. Furthermore, it is shown that - for suitable experimental conditions - the dynamical absorption curve contains information on the initial coherence between the ground state and the selected Rydberg state. We present the results of a proof-of-principle measurement performed on a cold gas of $^{87}$Rb atoms. The method is expected to find application in quantum computing protocols based on Rydberg atoms.
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.
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).
Two-photon adiabatic passage for excitation of Rydberg states
NASA Astrophysics Data System (ADS)
Malinovskaya, Svetlana; Liu, Gengyuan; Kuznetsova, Elena
2014-05-01
We study the excitation of the Rb atom to a Rydberg state in the blockaded regime and the excitation of two Rb atoms to Rydberg states in the regime of a weak blockade. For a single atom excitation, we describe a technique to realize two-photon adiabatic passage involving 5S1 / 2 , 5P1 / 2 , 3 / 2 and the Rydberg state modeled by a three level ladder system. The technique is based on using a pair of linearly chirped pulses, initially detuned off the one-photon resonance and satisfying the two-photon resonance condition at the time of peak pulse intensity. Secondly, we consider the excitation of two atoms to Rydberg states in the presence of dipole-dipole interaction between them. We find that an efficient excitation to the two-atom Rydberg state can be realized with two-photon adiabatic passage using chirped pulses with equal Rabi frequencies and chirp rates. High transfer efficiency can be achieved for pulse Rabi frequencies ?p , S >=Vint , where ?p , S is the Rabi frequency of the pump and Stokes pulses and Vint is the Rydberg-Rydberg interaction strength. The use of chirped pulses for performing two-photon transitions has a benefit of passing through the two-photon resonances whose frequencies are known only to a certain level of approximation. This work is supported by National Science Foundation.
Broad shape resonance effects in CaF Rydberg states.
Altunata, Serhan N; Coy, Stephen L; Field, Robert W
2006-05-21
Results of ab initio R-matrix calculations [S. N. Altunata et al., J. Chem. Phys. 123, 084319 (2005)] indicate the presence of a broad shape resonance in electron-CaF(+) scattering for the (2)Sigma(+) electronic symmetry near the ionization threshold. The properties of this shape resonance are analyzed using the adiabatic partial-wave expansion of the scattered electron wave function introduced by Le Dourneuf et al. [J. Phys. B 15, L685 (1982)]. The qualitative aspects of the shape resonance are explained by an adiabatic approximation on the electronic motion. Mulliken's rule for the structure of the Rydberg state wave functions [R. S. Mulliken, J. Am. Chem. Soc. 86, 3183 (1964)] specifies that, except for an (n*)(-32) amplitude scale factor, every excited state wave function within one Rydberg series is built on an innermost lobe that remains invariant in shape and nodal position as a function of the excitation energy. Mulliken's rule implies a weak energy dependence of the quantum defects for an unperturbed molecular Rydberg series, which is given by the Rydberg-Ritz formula. This zero-order picture is violated by a single (2)Sigma(+) CaF Rydberg series at all Rydberg state energies (n*=5-->infinity, more so with increasing n*) below the ionization threshold, under the broad width of the shape resonance. Such a violation is diagnostic of a global "scarring" of the Rydberg spectrum, which is distinct from the more familiar local level perturbations. PMID:16729809
Broad shape resonance effects in CaF Rydberg states
NASA Astrophysics Data System (ADS)
Altunata, Serhan N.; Coy, Stephen L.; Field, Robert W.
2006-05-01
Results of ab initio R-matrix calculations [S. N. Altunata et al., J. Chem. Phys. 123, 084319 (2005)] indicate the presence of a broad shape resonance in electron-CaF+ scattering for the ?+2 electronic symmetry near the ionization threshold. The properties of this shape resonance are analyzed using the adiabatic partial-wave expansion of the scattered electron wave function introduced by Le Dourneuf et al. [J. Phys. B 15, L685 (1982)]. The qualitative aspects of the shape resonance are explained by an adiabatic approximation on the electronic motion. Mulliken's rule for the structure of the Rydberg state wave functions [R. S. Mulliken, J. Am. Chem. Soc. 86, 3183 (1964)] specifies that, except for an (n*)-3/2 amplitude scale factor, every excited state wave function within one Rydberg series is built on an innermost lobe that remains invariant in shape and nodal position as a function of the excitation energy. Mulliken's rule implies a weak energy dependence of the quantum defects for an unperturbed molecular Rydberg series, which is given by the Rydberg-Ritz formula. This zero-order picture is violated by a single ?+2 CaF Rydberg series at all Rydberg state energies (n*=5??, more so with increasing n*) below the ionization threshold, under the broad width of the shape resonance. Such a violation is diagnostic of a global "scarring" of the Rydberg spectrum, which is distinct from the more familiar local level perturbations.
Ultralong-Range Cs D-State Rydberg Molecules
NASA Astrophysics Data System (ADS)
Yang, Jin; Reschke, Margarita; Furneaux, John; Booth, Donald; Shaffer, James
2015-05-01
Ultralong-range Rydberg molecules are interesting because they are formed by electron scattering of bound Rydberg electrons from ground state atoms found near an excited Rydberg atom. Because of their novel physical properties, such as kilo-Debye permanent dipole moments and novel binding mechanism, they are receiving increasing interest. Here, we present our work on ultralong-range Cs Rydberg molecules correlating asymptotically to d-states. Through comparison with prior experimental results on Rb and Cs ultralong-range molecules, we explain how state mixing and the details of different scattering processes work to give distinctive properties to these molecules that depend on quantum state and atomic species. We acknowledge funding from the NSF and the AFOSR.
All-optical measurement of Rydberg-state lifetimes
NASA Astrophysics Data System (ADS)
Mack, Markus; Grimmel, Jens; Karlewski, Florian; Sárkány, L?rinc; Hattermann, Helge; Fortágh, József
2015-07-01
We have developed an all-optical method for measuring the lifetimes of n S and n D Rydberg states and demonstrate its capabilities with measurements on a dilute cloud of ultracold 87Rb atoms in a cryogenic environment. The method is based on the time-resolved observation of resonant light absorption by ground-state atoms and selective transfer of Rydberg atoms into the ground state at varying delay times in order to reconstruct Rydberg decay curves. Our measurements of the 87Rb 30 S1 /2 state indicate an increase of the lifetime at lowered environment temperatures, as expected due to decreased blackbody radiation. For the 38 D5 /2 state with an attractive dipole-dipole interaction, ionization and lifetime reduction due to collisional effects are observed.
All-optical measurement of Rydberg state lifetimes
Mack, Markus; Karlewski, Florian; Sárkány, L?rinc; Hattermann, Helge; Fortágh, József
2015-01-01
We have developed an all-optical method for measuring the lifetimes of $n S$ and $n D$ Rydberg states and demonstrate its capabilities with measurements on a dilute cloud of ultracold ${}^{87}$Rb atoms in a cryogenic environment. The method is based on the time-resolved observation of resonant light absorption by ground state atoms and selective transfer of Rydberg atoms into the ground state at varying delay times in order to reconstruct Rydberg decay curves. Our measurements of the ${}^{87}$Rb $30S_{1/2}$ state indicate an increase of the lifetime at lowered environment temperatures, as expected due to decreased black body radiation. For the $38D_{5/2}$ state with an attractive dipole-dipole interaction, ionization and lifetime reduction due to collisional effects are observed.
Two-photon bound states in Rydberg gases
NASA Astrophysics Data System (ADS)
Moos, Matthias; Unanyan, Razmik; Fleischhauer, Michael
2015-05-01
We consider the propagation of photons in a gas of Rydberg atoms under conditions of electromagnetically induced transparency. Here the photons form strongly interacting massive particles, termed Rydberg polaritons. Recent experiments have realized strong interactions between Rydberg polaritons and shown photon blockade as well as pronounced bunching under off-resonant coupling conditions. We derive an effective Hamiltonian for Rydberg polaritons in one spatial dimension for off-resonant coupling. We show that in addition to repulsive polaritons bound pair-states of photons exist. For strong interactions, quantified in terms of optical depth per blockade distance, these states are deeply bound and cannot be prepared under typical experimental conditions. For small optical depth per blockade bound pair-states can, however, be excited near the threshold of the scattering continuum. Using numerical wave-function simulations we analyze the dynamics of the formation of bound states in a pulsed experiment and analyze their properties and time-evolution inside the medium. Furthermore we discuss the interaction between Rydberg polaritons and bound pairs and the pair-pair interaction.
Coherent excitation of a single atom to a Rydberg state
Y. Miroshnychenko; A. Gaëtan; C. Evellin; P. Grangier; D. Comparat; P. Pillet; T. Wilk; A. Browaeys
2010-05-12
We present the coherent excitation of a single Rubidium atom to the Rydberg state (58d3/2) using a two-photon transition. The experimental setup is described in detail, as well as experimental techniques and procedures. The coherence of the excitation is revealed by observing Rabi oscillations between ground and Rydberg states of the atom. We analyze the observed oscillations in detail and compare them to numerical simulations which include imperfections of our experimental system. Strategies for future improvements on the coherent manipulation of a single atom in our settings are given.
Spectroscopy of Potassium Rydberg States via Electromagnetically Induced Transparency
NASA Astrophysics Data System (ADS)
Xu, Wenchao; Demarco, Brian
2014-05-01
We perform precision spectroscopy of potassium Rydberg states in a heated vapor cell. The transition frequencies are obtained by observing electromagnetically induced transparency (EIT) features in a two-photon process: 4S1 / 2 --> 5P3 / 2 --> nS1 / 2 . We use a velocity selective optical pumping scheme to overcome Doppler broadening, which would suppress the EIT signal since the probe frequency is larger than the coupling frequency. Such precise spectroscopy will enable novel experiments with Rydberg-dressed ultracold Fermi gases.
Relaxation of antihydrogen from Rydberg to ground state
California at San Diego, University of
Relaxation of antihydrogen from Rydberg to ground state Eric M. Bass and Daniel H. E. Dubin antihydrogen experiments, form in the guiding-center atom regime. In this regime, the positron orbit is well in antihydrogen experiments do not relax out of the guiding-center regime to binding energies where radiation can
NASA Astrophysics Data System (ADS)
Kamenski, A. A.; Ovsiannikov, V. D.
2014-05-01
On the basis of analytical expressions in the Fues model potential approach for the second-order Stark effect on single-electron Rydberg states in atoms and ions, general equations are derived for coefficients of polynomials in powers of the principal quantum number n in asymptotic presentations of static scalar and tensor dipole polarizabilities. The power dependence for polarizabilities of isolated Rydberg states |nl> at n ? 1 scales as n7, in contrast with that of polarizabilities for hydrogenic states, degenerate in the orbital quantum number l ? n - 1, which scales as n6. This difference is demonstrated analytically in the asymptotic dependencies of the second-order matrix elements, determining the Stark shifts of the isolated and degenerate states. Analytical equations for polynomial coefficients use the data on quantum defects determined from the level energies of corresponding series of states. Numerical values of coefficients are presented for S-, P- and D-series of Rydberg states in neutral atoms of alkali-metal elements and helium in comparison with existing data of the literature. The analytical equations are also used for determining numerical values of coefficients in asymptotic polynomials for polarizabilities of Rydberg states in positive ions of alkaline-earth-metal elements.
Static and dynamic polarizability for C2+ in Rydberg states
NASA Astrophysics Data System (ADS)
Stancalie, V.
2015-07-01
This work presents results from a non-perturbative calculation of dynamic polarizability of C III ions in 1s22sns (1Se) Rydberg states. We employ a two-state model for dressed atomic states to investigate the effect of the frequency-dependent polarizability of optically dressed 1s22sns(1Se) states (n = 5 - 12) on transitions to nearby states (1s22pns(1P1o)). Our model calculation results indicate that the resonance structure of the polarizabilities is entirely captured by the transition terms whereas the free electron polarizability only provides a smooth background. The resonance structure is evident in the plots and the widths increase with increasing principal quantum number. This work refers to highly excited 1s22sns (1S) Rydberg states, embedded in the electric dipole field of the 2s - 2p core transition in Li-like C3+ ion. The contributions of the individual transitions to the static polarizabilities of these Rydberg states are obtained from the use of the sum-over-state method. To this aim, both the C2+ ground state and the C3+ target state energies have been carefully calculated based on the configuration interactions method implemented in the General-purpose Relativistic Atomic Structure Package. Agreement is reasonably good with existing data wherever available. These results are believed to be the first such values for this system and will be important for ionic spectroscopy and plasma diagnostics.
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 ?J+=0 and ?v+=0 propensity rules. However, in most molecules access to these states, via a sequence of ?l=+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.
Relativistic and radiative energy shifts for Rydberg states
NASA Astrophysics Data System (ADS)
Jentschura, Ulrich D.; LeBigot, Eric-Olivier; Evers, Jörg; Mohr, Peter J.; Keitel, Christoph H.
2005-01-01
We investigate relativistic and quantum electrodynamic effects for highly-excited bound states in hydrogen-like systems (Rydberg states). In particular, hydrogenic one-loop Bethe logarithms are calculated for all circular states (l = n - 1) in the range 20 <= n <= 60 and successfully compared to an existing asymptotic expansion for large principal quantum number n. We provide accurate expansions of the Bethe logarithm for large values of n, for S, P and circular Rydberg states. These three expansions are expected to give any Bethe logarithm for principal quantum number n > 20 to an accuracy of five to seven decimal digits, within the specified manifolds of atomic states. Within the numerical accuracy, the results constitute unified, general formulae for quantum electrodynamic corrections whose validity is not restricted to a single atomic state. The results are relevant for accurate predictions of radiative shifts of Rydberg states and for the description of the recently investigated laser-dressed Lamb shift, which is observable in a strong coherent-wave light field.
Neumark, Daniel M.
2012-01-01
of Rydberg atoms and molecular fragments from electronically excited helium nanodroplets Oliver Bünermann,1 of Rydberg atoms and molecular fragments from electronically excited he- lium nanodroplets are studiedV, Rydberg atoms in n = 3 and n = 4 states are ejected on different time scales and with significantly
Ionization of Rydberg H atoms at band-gap metal surfaces via surface and image states
NASA Astrophysics Data System (ADS)
So, E.; Gibbard, J. A.; Softley, T. P.
2015-09-01
Wavepacket propagation calculations are reported for the interaction of a Rydberg hydrogen atom (n=2-8) with Cu(111) and Cu(100) surfaces (represented by a Chulkov potential), in comparison with a Jellium surface. Both copper surfaces have a projected band gap at the surface in the energy range degenerate with some or all of the Rydberg energies. The charge transfer of the Rydberg electron to the surface is found to be enhanced for n values at which there is a near-degeneracy between the Rydberg energy level and an image state or a surface state of the surface. The enhancement is facilitated by the strong overlap of the surface image-state orbital lying outside the surface and the orbital of the incoming Rydberg atom. These calculations point to the possibility of using Rydberg-surface collisions as a probe of surface electronic structure.
Ionization of Rydberg H atoms at band-gap metal surfaces via surface and image states
So, E; Softley, T P
2015-01-01
Wavepacket propagation calculations are reported for the interaction of a Rydberg hydrogen atom ($n=2-8)$ with Cu(111) and Cu(100) surfaces (represented by a Chulkov potential), in comparison with a Jellium surface. Both copper surfaces have a projected band gap at the surface in the energy range degenerate with some or all of the Rydberg energies. The charge transfer of the Rydberg electron to the surface is found to be enhanced for $n$ values at which there is a near-degeneracy between the Rydberg energy level and an image state or a surface state of the surface. The enhancement is facilitated by the strong overlap of the surface image-state orbital lying outside the surface and the orbital of the incoming Rydberg atom. These calculations point to the possibility of using Rydberg-surface collisions as a probe of surface electronic structure.
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).
Pulsed-field ionization spectroscopy of high Rydberg states ,,n=50200... -benzene...chromium
Kim, Sang Kyu
Pulsed-field ionization spectroscopy of high Rydberg states ,,n=50200... of bis,, 6 -benzene...chromium The ionization behavior of the high Rydberg states of bis 6 -benzene chromium in the presence of ac and/or dc chromium, the accurate ionization potential is deduced to give IP=5.4665ą0.0003 eV. Optimization
Atomic and Molecular Low-n Rydberg States in Near Critical Point Fluids*
Findley, Gary L.
0 Atomic and Molecular Low-n Rydberg States in Near Critical Point Fluids* Luxi Li and Xianbo Shi at Monroe, Monroe, LA USA Abstract The structure of low-n Rydberg states doped into supercritical fluids are sensitive to the local fluid environment, dopant electronic transitions are an appropriate probe to study
Classical energy calculations with electron correlation of condensed excited states Rydberg Matter
Leif Holmlid
1998-01-01
A classical model is used to calculate the work function and the binding energy in condensed excited states, also named Rydberg Matter. The quantum mechanical description due to Manykin et al. shows that an excited matter exists, in which Rydberg states interact to give a gaseous metallic material with very low work function. Experimental evidence on a macroscopic level exists.
Optical spectroscopy of high-L Rydberg states of nickel
Keele, Julie A.; Woods, Shannon L.; Hanni, M. E.; Lundeen, S. R.; Sturrus, W. G.
2010-02-15
Binding energies of 23 Rydberg fine-structure levels of Ni with n = 9 and L{>=}5 were measured using resonant excitation Stark ionization spectroscopy. From this spectrum, the quadrupole moment and the scalar and tensor dipole polarizability of the {sup 2}D{sub 5/2} ground state of Ni{sup +} were determined to be Q=-0.474(2), {alpha}{sub d,0}=7.92(6), and {alpha}{sub d,2}=1.15(14) a.u. The electric hexadecapole moment was determined to be -0.33(21) a.u.
Selective production of Rydberg-stark states of positronium.
Wall, T E; Alonso, A M; Cooper, B S; Deller, A; Hogan, S D; Cassidy, D B
2015-05-01
Rydberg positronium (Ps) atoms have been prepared in selected Stark states via two-step (1s?2p?nd/ns) optical excitation. Two methods have been used to achieve Stark-state selection: a field ionization filter that transmits the outermost states with positive Stark shifts, and state-selected photoexcitation in a strong electric field. The former is demonstrated for n=17 and 18 while the latter is performed for n=11 in a homogeneous electric field of 1.9??kV/cm. The observed spectral intensities and their dependence on the polarization of the laser radiation are in agreement with calculations that include the perturbations of the intermediate n=2 manifold. Our results pave the way for the generation of Rydberg Ps atoms with large electric dipole moments that are required for the realization of schemes to control their motion using inhomogeneous electric fields, an essential feature of some proposed Ps free-fall measurements requiring focused beams of long-lived atoms. PMID:25978227
Rabi flopping between ground and Rydberg states with dipole-dipole atomic interactions
T. A. Johnson; E. Urban; T. Henage; L. Isenhower; D. D. Yavuz; T. G. Walker; M. Saffman
2007-11-02
We demonstrate Rabi flopping of small numbers of $\\rm{^{87}Rb}$ atoms between ground and Rydberg states with $n\\le 43$. Coherent population oscillations are observed for single atom flopping, while the presence of two or more atoms decoheres the oscillations. We show that these observations are consistent with van der Waals interactions of Rydberg atoms.
Introduction When ions are excited to a Rydberg state in ion traps, weakly bound
Hensinger, Winfried
Introduction When ions are excited to a Rydberg state in ion traps, weakly bound electrons render the system exotic properties, such as binding repulsive interacting ions into giant ionic molecules and achieving spin models as well as quantum gates in one dimensional Rydberg ions. Traditionally, ion traps
Constant-ionic-state spectroscopy of high-v Rydberg states of molecular hydrogen
NASA Astrophysics Data System (ADS)
Pratt, S. T.; Dehmer, P. M.; Dehmer, J. L.
1992-09-01
Photoelectron spectroscopy is used in combination with double-resonance excitation via the E,F 1Sigma-g(+), v = 6 state to reexamine the H2 spectrum in the region of the ion pair in order to elucidate the vibrational autoionization of the high-v Rydberg states and the details of the process of ion pair formation. The decay of the autoionizing Rydberg states is studied by both conventional and constant-ionic-state photoelectron spectrometry. The results support the Delta-v = minimum propensity rule for vibrational autoionization of Rydberg states with a high level of vibrational excitation. The relative intensities of the X 2Sigma-g(+)np, v-prime is not less than 9 Rydberg series converging to different rotational levels of the ion differ greatly from those for the analogous Rydberg series with v-prime is not greater than 2. This may be due to the dependence of the transition dipole matrix elements on the internuclear distance and to the presence of doubly excited electronic states that cross the H2(+) X 2Sigma-g(+) potential curve at a total energy close to that accessed by the two-color excitation scheme.
Deexcitation of high-Rydberg-state atoms with a chirped train of half-cycle pulses
NASA Astrophysics Data System (ADS)
Kopyciuk, T.; Parzy?ski, R.
2007-05-01
Encouraged by the experiments on production of antihydrogen atoms in high Rydberg states we have calculated the effect of deexcitation towards lower states by a chirped train of identical unidirectional half-cycle pulses. The calculations exploit both the one-dimensional and impulse approximations providing convenient analytical formulas for the Rydberg-to-Rydberg transition amplitudes. The calculated deexcitation is shown in terms of the mean value of localization of the Rydberg wave packet in the coordinate space, the Rydberg-state population distribution, the Husimi phase-space distribution function, and the probability density distribution, each of these measures vs the length of the applied train of half-cycle pulses. The results for chirped trains are compared with those for periodic trains and examples of higher deexcitation efficiency of the chirped trains are given.
Deexcitation of high-Rydberg-state atoms with a chirped train of half-cycle pulses
Kopyciuk, T.; Parzynski, R. [Faculty of Physics, A. Mickiewicz University, Umultowska 85, 61-614 Poznan (Poland)
2007-05-15
Encouraged by the experiments on production of antihydrogen atoms in high Rydberg states we have calculated the effect of deexcitation towards lower states by a chirped train of identical unidirectional half-cycle pulses. The calculations exploit both the one-dimensional and impulse approximations providing convenient analytical formulas for the Rydberg-to-Rydberg transition amplitudes. The calculated deexcitation is shown in terms of the mean value of localization of the Rydberg wave packet in the coordinate space, the Rydberg-state population distribution, the Husimi phase-space distribution function, and the probability density distribution, each of these measures vs the length of the applied train of half-cycle pulses. The results for chirped trains are compared with those for periodic trains and examples of higher deexcitation efficiency of the chirped trains are given.
Coherent Control of Rydberg States in Silicon
Greenland, P T; van der Meer, A F G; Murdin, B N; Pidgeon, C R; Redlich, B; Vinh, N Q; Aeppli, G; 10.1038/nature09112
2010-01-01
We demonstrate coherent control of donor wavefunctions in phosphorous-doped silicon. Our experiments take advantage of a free electron laser to stimulate and observe photon echoes from, and Rabi oscillations between the ground and first excited state of P donors in Si.
Rydberg States of Lithium and Other Systems
NASA Technical Reports Server (NTRS)
Drachman, Richard J.
1999-01-01
The interesting calculation of retardation corrections to excited atomic state energies is facilitated by the existence of good calculations of the nonrelativistic and nonretarded energies, to which retardation corrections can be added. Here I describe a perturbation method, applicable when the angular momentum is high enough which generates an asymptotic series for the energy. It makes use of generalized polarizabilities of the atomic or ionic core (numerically obtained) but otherwise is completely analytic. It is applied here to the lithium atom in detail, and its application to hydrogen molecular ions is outlined.
Two-photon spectroscopy of Rydberg states of molecular oxygen
NASA Astrophysics Data System (ADS)
Pratt, S. T.; Dehmer, J. L.; Dehmer, P. M.
1990-09-01
The (2 + 1) and two-photon ionization spectra of O2 provide a wealth of new information on the gerade Rydberg series converging to the X 2Pi(g) ground electronic state of O2(+). This paper extends these series to n = 8 for nu-prime = 0 and to n = 12 for n-prime = 1. The spectra display characteristic pairs of transitions to states with Omega(+) = 1/2 and 3/2 ion core that are separated by the O2(+) X 2Pi(1/2g) - 2Pi(3/2g) spin-orbit splitting. The quantum defects of the Omega(=) = 3/2 series members merge smoothly into that of the 3d pi 1Sigma(g)(+) state, providing a tentative assignment of this series.
Dressing of Ultracold Atoms by their Rydberg States in a Ioffe-Pritchard Trap
Mayle, Michael; Schmelcher, Peter
2010-01-01
We explore how the extraordinary properties of Rydberg atoms can be employed to impact the motion of ultracold ground state atoms. Specifically, we use an off-resonant two-photon laser dressing to map features of the Rydberg states on ground state atoms. It is demonstrated that the interplay between the spatially varying quantization axis of the considered Ioffe-Pritchard field and the fixed polarizations of the laser transitions provides the possibility of substantially manipulating the ground state trapping potential.
Two-color resonance ionization spectroscopy of Rydberg states of hafnium atoms
NASA Astrophysics Data System (ADS)
Matsuoka, Leo; Hasegawa, Shuichi
2006-12-01
We performed two-color resonance ionization spectroscopy to study the highly excited states of hafnium. We obtained the high-resolution spectra of the Rydberg series converging to the first ionization limit. These series of states have not been previously observed. From analyses of the main Rydberg series with Rydberg formula, we derived the ionization potential of hafnium as 55047.9ą0.1cm-1 . Comparing the spectra obtained through three different intermediate states, we could assign the J value of all the series in a certain energy region.
Two-color resonance ionization spectroscopy of Rydberg states of hafnium atoms
Matsuoka, Leo; Hasegawa, Shuichi
2006-12-15
We performed two-color resonance ionization spectroscopy to study the highly excited states of hafnium. We obtained the high-resolution spectra of the Rydberg series converging to the first ionization limit. These series of states have not been previously observed. From analyses of the main Rydberg series with Rydberg formula, we derived the ionization potential of hafnium as 55047.9{+-}0.1 cm{sup -1}. Comparing the spectra obtained through three different intermediate states, we could assign the J value of all the series in a certain energy region.
Magnetic trapping of ultracold Rydberg atoms in low angular momentum states
Mayle, Michael; Schmelcher, Peter
2009-01-01
We theoretically investigate the quantum properties of nS, nP, and nD Rydberg atoms in a magnetic Ioffe-Pritchard trap. In particular, it is demonstrated that the two-body character of Rydberg atoms significantly alters the trapping properties opposed to point-like particles with identical magnetic moment. Approximate analytical expressions describing the resulting Rydberg trapping potentials are derived and their validity is confirmed for experimentally relevant field strengths by comparisons to numerical solutions of the underlying Schroedinger equation. In addition to the electronic properties, the center of mass dynamics of trapped Rydberg atoms are studied. In particular, we analyze the influence of a short-time Rydberg excitation, as required by certain quantum-information protocols, on the center of mass dynamics of trapped ground state atoms. A corresponding heating rate is derived and the implications for the purity of the density matrix of an encoded qubit are investigated.
State-Mixing of nS Rydberg Atoms in an External Electric Field
NASA Astrophysics Data System (ADS)
Jiao, Yuechun; Wang, Limei; Zhang, Hao; Zhang, Linjie; Zhao, Jianming; Jia, Suotang
2015-09-01
State-mixing effect of ultracold nS cesium Rydberg atoms in an external electric field is investigated in a magneto-optical trap. Populated high-l Rydberg atoms due to the state-mixing through avoided crossings are measured with a state-selective field ionization technique. The measured transfer rates of high-l states increase with the electric field and get to the maximum at the field of about 3.0 V/cm for 49S1/2 Rydberg state, and show decrease behavior when the electric field increases further. The decrease behavior of the transfer rate is explained with the slower m-mixing effect caused by decreasing dipoledipole interactions between high-l Rydberg atoms. During the m-mixing process the ultracold plasma is formed by the Penning ionization.
Laser-enhanced ionization spectroscopy of mercury Rydberg states
NASA Astrophysics Data System (ADS)
Clevenger, W. L.; Matveev, O. I.; Omenetto, N.; Smith, B. W.; Winefordner, J. D.
1997-07-01
The spectral characteristics of mercury Rydberg states ( n = 10-42) were observed and studied. Each principal quantum number was observed as a triplet, and after observing a quartet of lines for n = 10, 11, and 12, these lines were assigned, from red to blue, as belonging to upper levels 1P 10, 3P 20, 3P 10, and 3P 00. These levels were studied as a function of variable applied high voltage (between the electrodes) and variable buffer gas pressure. In this way, the broadening and splitting caused by the influence of Stark effects and of increasing buffer gas pressure were observed for different n values. These observations will allow one to choose the optimal level for excitation, as well as the optimal operating conditions in terms of pressure and applied high voltage, for obtaining the best sensitivity and limit of detection by analytical laser-enhanced ionization spectroscopy.
(2 + n) REMPI of acetylene: Gerade Rydberg states and photorupture channels
Kristján Matthíasson; Huasheng Wang; Ágúst Kvaran
2008-01-01
Mass analysis studies were performed of ions detected after (2+n) REMPI of acetylene for resonance excitations to various gerade Rydberg states as a function of laser power. These data, along with STQN\\/DFT calculations for dissociation of acetylene to C2+H2, allowed an estimate of a threshold for photodissociation via gerade Rydberg states near 7500077000cm?1. Mechanisms are proposed regarding (2+3) REMPI of
Dopant low- n Rydberg states in CF 4 and CH 4 near the critical point
NASA Astrophysics Data System (ADS)
Li, Luxi; Shi, Xianbo; Findley, G. L.; Evans, C. M.
2009-11-01
Dopant low- n Rydberg states perturbed by dense CF 4 and CH 4 were investigated using vacuum ultraviolet photoabsorption spectroscopy at noncritical temperatures and on an isotherm near (+0.5 °C) the perturber critical temperature. A full analysis of these data using semi-classical line shape theory was performed. The perturber induced energy shift was extracted from the simulated bands and demonstrates a perturber critical point effect on the energy of low- n Rydberg states in these molecular fluids.
Single-Atom Addressing in Microtraps for Quantum-State Engineering using Rydberg Atoms
Labuhn, Henning; Barredo, Daniel; Béguin, Lucas; Nogrette, Florence; Lahaye, Thierry; Browaeys, Antoine
2014-01-01
We report on the selective addressing of an individual atom in a pair of single-atom microtraps separated by $3\\;\\mu$m. Using a tunable light-shift, we render the selected atom off-resonant with a global Rydberg excitation laser which is resonant with the other atom, making it possible to selectively block this atom from being excited to the Rydberg state. Furthermore we demonstrate the controlled manipulation of a two-atom entangled state by using the addressing beam to induce a phase shift onto one component of the wave function of the system, transferring it to a dark state for the Rydberg excitation light. Our results are an important step towards implementing quantum information processing and quantum simulation with large arrays of Rydberg atoms.
Collective state synthesis in an optical cavity using Rydberg atom dipole blockade
Santosh Kumar; Jiteng Sheng; Jonathon A. Sedlacek; Haoquan Fan; James P. Shaffer
2015-04-19
We investigate the coherent manipulation of interacting Rydberg atoms placed inside a high-finesse optical cavity for the preparation of strongly coupled light-matter systems. We consider a four-level diamond scheme with one common Rydberg level for $N$ interacting atoms. One side of the diamond is used to excite the atoms into a collective `superatom' Rydberg state using either $\\pi$-pulses or stimulated Raman adiabatic passage (STIRAP) pulses. The upper transition on the other side of the diamond is used to transfer the collective state to one that is coupled to a field mode of an optical cavity. Due to the strong interaction between the atoms in the Rydberg level, the Rydberg blockade mechanism plays a key role in the quantum state synthesis of the atoms in the cavity. We use numerical simulation to show that non-classical states of light can be generated and that the state that is coupled to the cavity field is a collective one. We also investigate how different decay mechanisms affect this interacting many-body system. We also analyze our system in the case of two Rydberg excitations within the blockade volume. The simulations are carried out with parameters corresponding to realizable high-finesse optical cavities and alkali atoms like rubidium.
Self-interaction corrected density functional calculations of molecular Rydberg states
Gudmundsdóttir, Hildur; Zhang, Yao; Weber, Peter M.; Jónsson, Hannes; Faculty of Physical Sciences, VR-III, University of Iceland, 107 Reykjavík
2013-11-21
A method is presented for calculating the wave function and energy of Rydberg excited states of molecules. A good estimate of the Rydberg state orbital is obtained using ground state density functional theory including Perdew-Zunger self-interaction correction and an optimized effective potential. The total energy of the excited molecule is obtained using the Delta Self-Consistent Field method where an electron is removed from the highest occupied orbital and placed in the Rydberg orbital. Results are presented for the first few Rydberg states of NH{sub 3}, H{sub 2}O, H{sub 2}CO, C{sub 2}H{sub 4}, and N(CH{sub 3}){sub 3}. The mean absolute error in the energy of the 33 molecular Rydberg states presented here is 0.18 eV. The orbitals are represented on a real space grid, avoiding the dependence on diffuse atomic basis sets. As in standard density functional theory calculations, the computational effort scales as NM{sup 2} where N is the number of orbitals and M is the number of grid points included in the calculation. Due to the slow scaling of the computational effort with system size and the high level of parallelism in the real space grid approach, the method presented here makes it possible to estimate Rydberg electron binding energy in large molecules.
A critical re-assignment of the Rydberg states of iodomethane based on new polarization data
NASA Astrophysics Data System (ADS)
Donovan, Robert J.; Hennessy, John T.; Lawley, Kenneth P.; Ridley, Trevor
2013-04-01
2- and 3-photon excitation of components of the lower Rydberg states of iodomethane (CH3I) using linearly and circularly polarized light, followed by ionization with one more photon, is used to determine their molecular term symbol, ?, values as well as quantum defects. These ? values, together with a detailed theoretical analysis, require a re-assignment of the 7s and 8s states to various components of the 5d and 6d states, but there is evidence of (n+2)s/nd hybridization in the pairs of ? = 1 states. Predissociation sets in for all Rydberg states beyond 6d based on the ground (2?3/2) state of the core, but sharp autoionizing resonances based on the 2?1/2 core state are assigned to the 9s, 7d, and 5f states. The dominant effect of the singlet/triplet character of the Rydberg states on their accessibility from the ground state, seen in bromomethane and chloromethane, is again apparent and a concordant interpretation of the Rydberg spectra of CH3I can now be presented. Evidence for coupling of some ? = 1 and ? = 0+ Rydberg states with a repulsive valence state and an ion-pair state, respectively, is also put forward.
Sub-Poissonian statistics of Rydberg-interacting dark-state polaritons.
Hofmann, C S; Günter, G; Schempp, H; Robert-de-Saint-Vincent, M; Gärttner, M; Evers, J; Whitlock, S; Weidemüller, M
2013-05-17
We observe individual dark-state polaritons as they propagate through an ultracold atomic gas involving Rydberg states coupled via an electromagnetically induced transparency resonance. Strong long-range interactions between Rydberg excitations give rise to a blockade between polaritons, resulting in large optical nonlinearities and modified polariton number statistics. By combining optical imaging and high-fidelity detection of the Rydberg polaritons we investigate both aspects of this coupled atom-light system. We map out the full nonlinear optical response as a function of atomic density and follow the temporal evolution of polaritons through the atomic cloud. In the blockade regime, the statistical fluctuations of the polariton number drop well below the quantum noise limit. The low level of fluctuations indicates that photon correlations modified by the strong interactions have a significant backaction on the Rydberg atom statistics. PMID:25167407
Pulsed excitation of Rydberg-atom-pair states in an ultracold Cs gas
NASA Astrophysics Data System (ADS)
Saßmannshausen, Heiner; Merkt, Frédéric; Deiglmayr, Johannes
2015-09-01
Pulsed laser excitation of a dense ultracold Cs vapor has been used to study the pairwise interactions between Cs atoms excited to n p3 /2 Rydberg states of principal quantum numbers in the range n =22 -36 . Molecular resonances were observed that correspond to excitation of Rydberg-atom-pair states correlated not only to the n p3 /2+n p3 /2 dissociation asymptotes, but also to n s1 /2+(n +1 ) s1 /2 , n s1 /2+n'fj , and (n -4 ) fj+(n -3 ) fj(j =5 /2 ,7 /2 ) dissociation asymptotes. These pair resonances are interpreted as arising from dipole-dipole and higher-order long-range-interaction terms between the Rydberg atoms on the basis of (i) their spectral positions, (ii) their response to static and pulsed electric fields, and (iii) millimeter-wave spectra between pair states correlated to different pair-dissociation asymptotes. The Rydberg-atom-pair states were found to spontaneously decay by Penning ionization and the dynamics of the ionization process were investigated during the first 15 ? s following initial photoexcitation. To interpret the experimental observations, a potential model was derived that is based on the numerical determination of the eigenvalues and eigenfunctions of the long-range interaction Hamiltonian. With this potential model, which does not include adjustable parameters, all experimental observations could be accounted for, and the results demonstrate that long-range-interaction models provide a global and accurate description of interactions in ultracold Rydberg gases and that they correctly account for, and enable the analysis of, phenomena as diverse as the formation of Rydberg macrodimers, Penning ionization in dense Rydberg gases, and Rydberg-excitation-blockade effects.
Excited states of the water molecule: analysis of the valence and Rydberg character.
Rubio, Mercedes; Serrano-Andrés, Luis; Merchán, Manuela
2008-03-14
The excited states of the water molecule have been analyzed by using the extended quantum-chemical multistate CASPT2 method, namely, MS-CASPT2, in conjunction with large one-electron basis sets of atomic natural orbital type. The study includes 13 singlet and triplet excited states, both valence and 3s-, 3p-, and 3d-members of the Rydberg series converging to the lowest ionization potential and the 3s- and 3p-Rydberg members converging to the second low-lying state of the cation, 1 (2)A(1). The research has been focused on the analysis of the valence or Rydberg character of the low-lying states. The computation of the 1 (1)B(1) state of water at different geometries indicates that it has a predominant 3s-Rydberg character at the equilibrium geometry of the molecule but it becomes progressively a valence state described mainly by the one-electron 1b(1)-->4a(1) promotion, as expected from a textbook of general chemistry, upon elongation of the O-H bonds. The described valence-Rydberg mixing is established to be originated by a molecular orbital (MO) Rydbergization process, as suggested earlier by R. S. Mulliken [Acc. Chem. Res. 9, 7 (1976)]. The same phenomenon occurs also for the 1 (1)A(2) state whereas a more complex behavior has been determined for the 2 (1)A(1) state, where both MO Rydbergization and configurational mixing take place. Similar conclusions have been obtained for the triplet states of the molecule. PMID:18345886
Electrons above a Helium Surface and the One-Dimensional Rydberg Atom
Michael Martin Nieto
1999-11-17
Isolated electrons resting above a helium surface are predicted to have a bound spectrum corresponding to a one-dimensional hydrogen atom. But in fact, the observed spectrum is closer to that of a quantum-defect atom. Such a model is discussed and solved in analytic closed form.
Predissociation of high-lying Rydberg states of molecular iodine via ion-pair states
Bogomolov, Alexandr S.; Grüner, Barbara; Mudrich, Marcel; Kochubei, Sergei A.; Baklanov, Alexey V.; Novosibirsk State University, Pirogova Str. 2, Novosibirsk 630090
2014-03-28
Velocity map imaging of the photofragments arising from two-photon photoexcitation of molecular iodine in the energy range 73?50074?500 cm{sup ?1} covering the bands of high-lying gerade Rydberg states [{sup 2}?{sub 1/2}]{sub c}6d;0{sub g}{sup +} and [{sup 2}?{sub 1/2}]{sub c}6d;2{sub g} has been applied. The ion signal was dominated by the atomic fragment ion I{sup +}. Up to 5 dissociation channels yielding I{sup +} ions with different kinetic energies were observed when the I{sub 2} molecule was excited within discrete peaks of Rydberg states and their satellites in this region. One of these channels gives rise to images of I{sup +} and I{sup ?} ions with equal kinetic energy indicating predissociation of I{sub 2} via ion-pair states. The contribution of this channel was up to about 50% of the total I{sup +} signal. The four other channels correspond to predissociation via lower lying Rydberg states giving rise to excited iodine atoms providing I{sup +} ions by subsequent one-photon ionization by the same laser pulse. The ratio of these channels varied from peak to peak in the spectrum but their total ionic signal was always much higher than the signal of (2 + 1) resonance enhanced multi-photon ionization of I{sub 2}, which was previously considered to be the origin of ionic signal in this spectral range. The first-tier E0{sub g}{sup +} and D{sup ?}2{sub g} ion-pair states are concluded to be responsible for predissociation of Rydberg states [{sup 2}?{sub 1/2}]{sub c}6d;0{sub g}{sup +} and [{sup 2}?{sub 1/2}]{sub c}6d;2{sub g}, respectively. Further predissociation of these ion-pair states via lower lying Rydberg states gives rise to excited I(5s{sup 2}5p{sup 4}6s{sup 1}) atoms responsible for major part of ion signal. The isotropic angular distribution of the photofragment recoil directions observed for all channels indicates that the studied Rydberg states are long-lived compared with the rotational period of the I{sub 2} molecule.
Excitation of Rydberg states in rubidium with near infrared diode lasers.
Fahey, Donald P; Noel, Michael W
2011-08-29
A system of three external cavity diode lasers is used to excite Rydberg states in rubidium. The 5S?5P?5D transitions are driven using lasers with ? = 780 and 776 nm respectively. From the 5D state, atoms fluoresce down to the 6P state. The final transition to Rydberg levels is from the 6P state with laser light near ? = 1016 nm. The nS and nD Rydberg states are accessible directly and with the application of a modest electric field nP states can also be excited. As a test of this system, Stark spectra are collected for nD and nP states. PMID:21935060
Ground State of the Helium Atom. II
Toichiro Kinoshita
1959-01-01
A further attempt is made to improve the theoretical prediction of the energy of the ground state of atomic helium. The nonrelativistic part is treated by the variational method of Stevenson and Crawford which is useful for improving the lower bound for the ground-state energy. Linear combinations of up to 80 terms of generalized Hylleraas type are employed in the
NASA Astrophysics Data System (ADS)
Liu, Jinjun; Sprecher, Daniel; Raunhardt, Matthias; Schäfer, Martin; Merkt, Frédéric
2009-06-01
A supersonic beam of metastable He_2^* a ^3?_{u}^+ molecules was generated using a pulsed discharge at the exit of a pulsed valve prior to the gas expansion into vacuum. Transitions to high np Rydberg states were recorded using photoionization and Rydberg-state-resolved threshold ionization spectroscopy. Overview scans at moderate resolution (0.3 cm^{-1}) were obtained with ionization fields ranging from 1.3 to 133 V/cm, lowering the ionization thresholds by 5.5 and 55 cm^{-1}, respectively. Using a solid-state UV laser system with a 20 MHz bandwidth, high-resolution spectra of Rydberg series with n up to 150 and with resolved fine structure of the initial He_2^* a ^3?_{u}^+ (N'') state were recorded. The assignment of the observed Rydberg states is based on multichannel quantum defect theory calculations from a recent study^a of pulsed-field-ionization zero-kinetic-energy (PFI-ZEKE) photoelectron and photoionization spectra of He_2 (see following talk). The extrapolation of the observed Rydberg series to their limits enabled the determination of the ionization energy of the a ^3?_{u}^+ state and the rotational structure of the He_2^+ ion with a precision of better than 20 MHz. M. Raunhardt, M. Schäfer, N. Vanhaecke, F. Merkt}, J. Chem. Phys. 128, 164310 (2008). R. Seiler, U. Hollenstein, G. M. Greetham, F. Merkt, Chem. Phys. Lett. 346, 201 (2001). R. Seiler, Th. A. Paul, M. Andrist, F. Merkt}, Rev. Sci. Instr. 76, 103103 (2005). M. Raunhardt, M. Schäfer, N. Vanhaecke, F. Merkt, J. Chem. Phys. 128, 164310 (2008).
Highly excited Rydberg states of hydrogen from a high-temperature diffusion source
E. Wallin; T. Hansson; L. Holmlid
1992-01-01
The methods used for formation and observation of HR (highly excited Rydberg) states of alkali are here adopted for the study of hydrogen HR states. Electronically highly excited states are formed in a hydrogen-filled diffusion source with a graphite foil as emitter at high temperature. The excited states are detected by electrostatic methods, mainly by their interaction with a well
Two-color photoexcitation of Rydberg states via an electric quadrupole transition
Li Leping; Gu Quanli; Knee, J. L.; Wright, J. D.; DiSciacca, J. M.; Morgan, T. J.
2008-03-15
We report the observation of an electric quadrupole transition between the 4s{sup '}[1/2]{sub 0}{sup o} and 3d[3/2]{sub 2}{sup o} states in the spectrum of argon and use it in the first step of a scheme to excite Rydberg states. The initial identification of the transition is based on one-color, two-photon photoionization. A different experiment utilizing two-color, two-photon photoexcitation to Rydberg states confirms the identification. Despite the unavoidable background of one-color, two-photon photoionization, the latter experimental technique makes possible two-photon spectroscopy of Rydberg states using a resonant intermediate state populated by an electric quadrupole transition.
Single Photon Transistor Mediated by Inter-State Rydberg Interaction
Hannes Gorniaczyk; Christoph Tresp; Johannes Schmidt; Helmut Fedder; Sebastian Hofferberth
2014-04-24
We report on the realization of an all-optical transistor by mapping gate and source photons into strongly interacting Rydberg excitations with different principal quantum numbers in an ultracold atomic ensemble. We obtain a record switch contrast of 40 % for a coherent gate input with mean photon number one and demonstrate attenuation of source transmission by over 10 photons with a single gate photon. We use our optical transistor to demonstrate the nondestructive detection of a single Rydberg atom with a fidelity of 0.72(4).
NASA Astrophysics Data System (ADS)
Kumar, Santosh; Sheng, Jiteng; Sedlacek, Jonathon; Ewel, Charlie; Fan, Haoquan; Shaffer, James
2015-05-01
We investigate the coherent manipulation of interacting Rydberg atoms placed inside a high-finesse optical cavity for the preparation of strongly coupled light-matter systems. We consider a four-level diamond scheme with one common Rydberg level. One side of the diamond is used to collectively excite the atoms to the Rydberg level using a pair of pulses. The other side of the diamond is used to produce a collective state that is close to resonance with a field mode of a high-finesse optical cavity. The interaction between Rydberg atoms creates a blockade which is useful for synthesizing the coherent collective state. We use numerical simulation to generate non-classical states of light and also investigate different decay mechanisms affecting this system. We also analyze our system in the case of two Rydberg excitations within the blockade volume. In this case, we show that more elaborate few excitation quantum states can be prepared in the cavity to observe interesting dynamics and analyze the correlation of the two-photon emission. This work is supported by the DARPA Quasar program by a grant through ARO, AFOSR and NSF.
Photoionization from excited states of helium
NASA Technical Reports Server (NTRS)
Jacobs, V. L.
1973-01-01
The cross sections for photoionization from the 2 1S, 2 3S, 2 1P and 2 3P excited states of helium are calculated for photoelectron energies below the n = 2 threshold of He(+) using Hylleraas bound state wave functions and 1s-2s-2p close coupling final state wave functions. The resonant structures associated with the lowest-lying 1S, 1P, 3P, and 1D autoionizing states of helium are found to be characterized by large values of the line profile parameter q. The cross sections and the photoelectron angular distribution asymmetry parameters for the P-states are calculated for various polarization states of the target atom and the incident photon. Experiments which would lead to the separate determinations of the S- and D- wave partial photoionization cross sections are discussed.
Ground State of the Helium Atom
Toichiro Kinoshita
1957-01-01
The energy level of the ground state of atomic helium is restudied in detail. The nonrelativistic part is treated by the conventional Ritz variation technique. However, the trial functions used are more general than the ordinary Hylleraas-type functions since they contain negative power terms in addition to the positive power terms. Linear combinations of up to 39 terms are employed
Ramsey, J.M.; Whitten, W.B.; Goeringer, D.E.; Buckley, B.T.
1990-01-01
Rydberg states of rubidium are selectively generated by one and two photon laser excitation in a quadrupole ion trap mass spectrometer. Collisional and electric-field ionization is investigated in trapping device. CCl{sub 4} is studied as a target for ionization of Rydberg states through electron attachment.
High-lying Rydberg states of vinyl bromide studied by two-photon resonant ionization spectroscopy
NASA Astrophysics Data System (ADS)
Chuang, Chi-Hung; Chen, Chun-Cing; Wu, Hsing-Chen; Chen, Yit-Tsong
2004-08-01
High-lying Rydberg states of vinyl bromide at 70 000-79 500 cm -1 have been investigated using 2 + 1 resonance-enhanced multiphoton ionization (REMPI) spectroscopy. Seven Rydberg series, including one s, three p, two d, and one f, have been identified from fitting the term values of observed electronic states to Rydberg formula rendering the ionization energy of 79 194 ą 17 cm -1 (9.819 ą 0.002 eV). All of the seven series converge to the same ionization-energy limit, corresponding to the ground state of vinyl bromide cation. The adiabatic ionization energy of vinyl bromide determined from this study is in excellent agreement with the values reported recently by other methods.
Van der Waals Interactions among Alkali Rydberg Atoms with Excitonic States
Zoubi, Hashem
2015-01-01
We investigate the influence of the appearance of excitonic states on van der Waals interactions among two Rydberg atoms. The atoms are assumed to be in different Rydberg states, e.g., in the $|ns\\rangle$ and $|np\\rangle$ states. The resonant dipole-dipole interactions yield symmetric and antisymmetric excitons, with energy splitting that give rise to new resonances as the atoms approach each other. Only far from these resonances the van der Waals coefficients, $C_6^{sp}$, can be defined. We calculate the $C_6$ coefficients for alkali atoms and present the results for lithium by applying perturbation theory. At short interatomic distances of several $\\mu m$, we show that the widely used simple model of two-level systems for excitons in Rydberg atoms breaks down, and the correct representation implies multi-level atoms. Even though, at larger distances one can keep the two-level systems but in including van der Waals interactions among the atoms.
Xenon low- n Rydberg states in supercritical argon near the critical point
NASA Astrophysics Data System (ADS)
Li, Luxi; Shi, Xianbo; Evans, C. M.; Findley, G. L.
2008-08-01
We present vacuum ultraviolet absorption spectra and an asymmetric line shape simulation of the 6s and 6s' Rydberg states (including the blue satellite bands) of xenon doped into argon, from low argon number density to the density of the triple point liquid, at both non-critical temperatures and near (+0.5 °C) the critical isotherm of argon (i.e., -122.3 °C). The argon-induced shift in the simulated primary transition of the Xe 6s and 6s' Rydberg states is presented as a function of argon number density for non-critical temperatures and along an isotherm near the critical temperature. This shift demonstrates a perturber critical point effect on the transition energies of low- n dopant Rydberg states.
CH 3I low- n Rydberg states in supercritical atomic fluids near the critical point
NASA Astrophysics Data System (ADS)
Li, Luxi; Shi, Xianbo; Evans, C. M.; Findley, G. L.
2009-06-01
Vacuum ultraviolet photoabsorption spectra of CH3I 6s and 6s? Rydberg states doped into supercritical argon, krypton, and xenon perturbers were measured from low density to the density of the triple point liquid at noncritical temperatures and on an isotherm near the perturber critical temperature. A full line shape analysis of these spectra was performed using a single set of intermolecular potential parameters for each dopant/perturber system. The resulting perturber induced shift of the simulated adiabatic transition of the 6s and 6s? Rydberg states is presented as a function of perturber number density, and this shift illustrates a perturber critical point effect on the excitation energies of the molecular low-n Rydberg states.
Van der Waals interactions among alkali Rydberg atoms with excitonic states
NASA Astrophysics Data System (ADS)
Zoubi, Hashem
2015-09-01
We investigate the influence of the appearance of excitonic states on van der Waals interactions among two Rydberg atoms. The atoms are assumed to be in different Rydberg states, e.g., in the | {ns}> and | {np}> states. The resonant dipole-dipole interactions yield symmetric and antisymmetric excitons, with energy splitting that give rise to new resonances as the atoms approach each other. Only away from these resonances can the van der Waals coefficients, C6sp, be defined. We calculate the C6 coefficients for alkali atoms and present the results for lithium by applying perturbation theory. At short interatomic distances of several ? {{m}}, we show that the widely used simple model of two-level systems for excitons in Rydberg atoms breaks down, and the correct representation implies multi-level atoms. Even though, at larger distances one can keep the two-level systems but in including van der Waals interactions among the atoms .
Separation of long-range and short-range interactions in Rydberg states of diatomic molecules
NASA Astrophysics Data System (ADS)
Kay, Jeffrey J.; Coy, Stephen L.; Petrovi?, Vladimir S.; Wong, Bryan M.; Field, Robert W.
2008-05-01
Observation and analysis of the f(? =3), g(? =4), and h(? =5) Rydberg series of CaF in the range 13?n?17 is presented. Simultaneous analysis of the f, g, and h Rydberg series of CaF, combined with significant improvements to the long-range model for nonpenetrating Rydberg states, provides a generally applicable scheme for separating the effects of the long-range (electric multipole and polarization) and short-range (core penetration) interactions between the Rydberg electron and ion core in diatomic molecules. Techniques for rigorous assignment of nonpenetrating states, as well as extensions of the long-range model, are discussed. Explicit formulas for the first- and second-order matrix elements of the first four anisotropic electric multipole interactions (electric dipole, quadrupole, octupole, and hexadecapole) are given. The discrepancies between the observed behavior and that predicted by the long-range model, which are particularly significant for the f series, are shown to be due to penetration of the Rydberg electron wavefunction within the ion core. We show that these penetration effects can be understood within the framework of ligand field theory and conclude with a discussion of the relative contributions of the long- and short-range interactions to the quantum defects of the core-penetrating "s," "p," and "d" series of CaF.
Radiative lifetime and photoionization cross-section for Rydberg states in alkali-metal atoms
NASA Astrophysics Data System (ADS)
Ovsiannikov, V. D.; Glukhov, I. L.; Nekipelov, E. A.
2011-07-01
General properties were determined and asymptotic approximation formulas for probabilities of spontaneous decay and photoionization cross-sections were derived on the basis of numerically calculated amplitudes of bound-bound and bound-free radiation transitions from Rydberg nS-, nP- and nD-states of alkali atoms with high principal quantum numbers, up to n = 1000. The departure of data from the asymptotic formulas for states with principal quantum numbers in the range between n = 10 and n = 2000 from originally calculated data does not exceed 0.1-1%, and may be useful for estimations of natural radiation widths for arbitrary high Rydberg levels.
NASA Astrophysics Data System (ADS)
Feng, Qiang; Xu, Yun-Feng; Sun, Jin-Da; Tian, Shan-Xi; Shan, Xiao-Bin; Liu, Fu-Yi; Sheng, Liu-Si
2009-10-01
Photodissociation efficiency spectrum of anionic oxygen atom produced via ion-pair dissociations of carbon dioxide is recorded by means of the synchrotron radiation excitation (XUV photon energy 17.40-20.00 eV). The present spectrum is assigned as the Rydberg-like excited ion-pair states, i.e., Tanaka-Ogawa and Henning series, tilde C2?g+ (CO+2) vibrational ground-state and excitation series. Three Rydberg series, np?u, np?u, and nfu, converging to tilde C2?g+ (0, 0, 0), show the higher cross sections.
Photoexcitation of n 305 Rydberg States in the Presence of an rf Drive Field
Yoshida, S [Inst. for Theoretical Phys., Vienna Univ. of Technology; Reinhold, Carlos O [ORNL; Burgdorfer, J. [Vienna University of Technology, Austria; Ye, S [Rice Quantum Inst., Rice University; Dunning, F. B. [Rice University
2012-01-01
The response of highly excited potassium Rydberg states with n 305 to a sinusoidal electric drive field in the radio frequency (100 300 MHz) regime is examined by photoexcitation from the 4s ground state using a uv probe beam. The drive field couples many Rydberg levels simultaneously and results in a coherent response that leads to a variety of multiphoton processes. The excitation spectra are analyzed within the framework of Floquet theory and reveal signatures of quantum optical phenomena such as electromagnetically induced transparency and Autler-Townes splitting seen with few-level systems.
GHz Rabi Flopping to Rydberg States in Hot Atomic Vapor Cells
Huber, B.; Baluktsian, T.; Schlagmueller, M.; Koelle, A.; Kuebler, H.; Loew, R.; Pfau, T.
2011-12-09
We report on the observation of Rabi oscillations to a Rydberg state on a time scale below 1 ns in thermal rubidium vapor. We use a bandwidth-limited pulsed excitation and observe up to 6 full Rabi cycles within a pulse duration of {approx}4 ns. We find good agreement between the experiment and numerical simulations based on a surprisingly simple model. This result shows that fully coherent dynamics with Rydberg states can be achieved even in thermal atomic vapor, thus suggesting small vapor cells as a platform for room-temperature quantum devices. Furthermore, the result implies that previous coherent dynamics in single-atom Rydberg gates can be accelerated by 3 orders of magnitude.
GHz Rabi Flopping to Rydberg States in Hot Atomic Vapor Cells
NASA Astrophysics Data System (ADS)
Huber, B.; Baluktsian, T.; Schlagmüller, M.; Kölle, A.; Kübler, H.; Löw, R.; Pfau, T.
2011-12-01
We report on the observation of Rabi oscillations to a Rydberg state on a time scale below 1 ns in thermal rubidium vapor. We use a bandwidth-limited pulsed excitation and observe up to 6 full Rabi cycles within a pulse duration of 4ns. We find good agreement between the experiment and numerical simulations based on a surprisingly simple model. This result shows that fully coherent dynamics with Rydberg states can be achieved even in thermal atomic vapor, thus suggesting small vapor cells as a platform for room-temperature quantum devices. Furthermore, the result implies that previous coherent dynamics in single-atom Rydberg gates can be accelerated by 3 orders of magnitude.
Lifetimes of ultralong-range Rydberg molecules in vibrational ground and excited states
NASA Astrophysics Data System (ADS)
Butscher, Björn; Bendkowsky, Vera; Nipper, Johannes; Balewski, Jonathan B.; Kukota, Ludmila; Löw, Robert; Pfau, Tilman; Li, Weibin; Pohl, Thomas; Rost, Jan Michael
2011-09-01
Since their first experimental observation, ultralong-range Rydberg molecules consisting of a highly excited Rydberg atom and a ground state atom [1, 2] have attracted the interest in the field of ultracold chemistry [3, 4]. Especially the intriguing properties such as size, polarizability and type of binding they inherit from the Rydberg atom are of interest. An open question in the field is the reduced lifetime of the molecules compared to the corresponding atomic Rydberg states [2]. In this paper we present an experimental study on the lifetimes of the 3?(5s - 35s) molecule in its vibrational ground state and in an excited state. We show that the lifetimes depend on the density of ground state atoms and that this can be described in the frame of a classical scattering between the molecules and ground state atoms. We also find that the excited molecular state has an even more reduced lifetime compared to the ground state which can be attributed to an inward penetration of the bound atomic pair due to imperfect quantum reflection that takes place in the special shape of the molecular potential [5].
Approximate Rydberg States of the Hydrogen Atom that are Concentrated near Kepler Orbits
study the semiclassical limit for bound states of the Hydrogen atom Hamiltonian H(~) = \\Gamma ~ 2 2Approximate Rydberg States of the Hydrogen Atom that are Concentrated near Kepler Orbits George A \\Delta \\Gamma 1 jxj : For each Kepler orbit of the corresponding classical system, we construct a lowest
Coherent population transfer of ground-state atoms into Rydberg states
Cubel, T.; Teo, B.K.; Malinovsky, V.S.; Guest, J.R.; Reinhard, A.; Knuffman, B.; Berman, P.R.; Raithel, G.
2005-08-15
The technique of stimulated Raman adiabatic passage (STIRAP) is used to excite laser-cooled rubidium atoms from the {sup 85}Rb 5S{sub 1/2} ground state to the 44D{sub 5/2} Rydberg state through the 5P{sub 3/2} state. The utilized double-STIRAP scheme allows for an accurate determination of the absolute excitation efficiency. Experimental data are compared with results of a detailed theoretical model, and good agreement is found. It is concluded that at the center of the excitation region an excitation efficiency of 70% is achieved.
NASA Astrophysics Data System (ADS)
Moise, Angelica; Alagia, Michele; Banchi, Luca; Ferianis, Mario; Prince, Kevin C.; Richter, Robert
2008-04-01
A mode-locked tunable Ti:Sapphire oscillator has been synchronized with the time structure of a storage ring and used to study the photoionization of noble gases. In multi-bunch operation of the ring the setup permits the observation of the dynamics from a few nanoseconds down to the tens of picoseconds range. The characteristics of the setup are demonstrated by following the two-color ionization of helium (via the 1s3p 1P o state) and argon (via the 3p 5 ( 2P 3/2) 3d state). In the CW mode we have also examined the two-color ionization of neon via the 2p 5 ( 2P 1/2) 3d' state. In neon the nf' Rydberg series was followed up to n50, and the quantum defect was determined.
Doppler- and recoil-free laser excitation of Rydberg states via three-photon transitions
Ryabtsev, I. I.; Beterov, I. I.; Tretyakov, D. B.; Entin, V. M.; Yakshina, E. A.
2011-11-15
Three-photon laser excitation of Rydberg states by three different laser beams can be arranged in a starlike geometry that simultaneously eliminates the recoil effect and Doppler broadening. Our analytical and numerical calculations for a particular laser excitation scheme 5S{sub 1/2}{yields}5P{sub 3/2}{yields}6S{sub 1/2}{yields}nP in Rb atoms have shown that, compared to the one- and two-photon laser excitation, this approach provides much narrower linewidth and longer coherence time for both cold atom samples and hot vapors, if the intermediate one-photon resonances of the three-photon transition are detuned by more than respective single-photon Doppler widths. This method can be used to improve fidelity of Rydberg quantum gates and precision of spectroscopic measurements in Rydberg atoms.
Millimetre-wave spectroscopy of Au I Rydberg states: S, P and D terms
NASA Astrophysics Data System (ADS)
Dyubko, S. F.; Efremov, V. A.; Gerasimov, V. G.; MacAdam, K. B.
2005-04-01
Energy levels of laser-excited Au I Rydberg states n = 25-38 in n2S1/2, n2P1/2,3/2 and n2D3/2 series have been measured by means of millimetre-wave spectroscopy in the frequency range 80-300 GHz. In this n region, Rydberg progressions were smooth and regular within the ą1 MHz measurement accuracy, and quantum-defect Rydberg-Ritz coefficients for these series have been obtained in a single-channel analysis. The doublet fine-structure splittings of P terms for n = 14-36, combining old and new data, have been fitted by an expansion formula. An improved value of the first ionization potential for Au I is VIP = 74 409.11 ą 0.03 cm-1.
Asymptotic description of the Rydberg states with {L > 0} in a two-electron atom
NASA Astrophysics Data System (ADS)
Ivanov, I. A.
2003-12-01
The energies of the levels belonging to a Rydberg series 1 snp 1,3P in a two electron atom have been determined by means of the quantum defect theory for a two-electron atom with nuclear charge Z considered as a parameter. Comparison with configuration interaction calculations suggests that the analytic quantum defect expression for the energy levels may be in fact asymptotically exact as Z to 1, providing an analytic description of the disappearance of the Rydberg states with L > 0 when Z approaches the value of 1.
Ground State of the Helium Atom
Charles Schwartz
1962-01-01
Following a recent attempt to analyze the rate of convergence of Rayleigh-Ritz variational calculations on the ground state of helium, we were led to re-investigate the usefulness of inserting fractional powers of the variables into the conventional Hylleraas series. The results have been very successful: With a 164-term trial function containing half-powers of the variable s=r1+r2, we have matched the
Observation of g/u-symmetry mixing in the high-n Rydberg states of HD
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 +} = 02) levels of the X{sup +2}?{sub g}{sup +} electronic ground state of HD{sup +} were studied by high-resolution spectroscopy from the GK{sup 1}?{sub g}{sup +} (v= 1, N = 1) state under field-free conditions. Three effects of g/u-symmetry breaking were detected: (i) Single-photon transitions from the GK?(v = 1, N = 1) state of gerade symmetry to the 30d2{sub 1} and 31g2{sub 2} Rydberg states of gerade symmetry were observed after careful compensation of the stray electric fields. (ii) The singlet 61p1{sub 2} Rydberg state of ungerade symmetry was found to autoionize to the N{sup +} = 0,?? = 2 ionization continuum of gerade symmetry with a lifetime of 77(10)?ns. (iii) Shifts of up to 20?MHz induced by g/u-symmetry mixing were measured for members of the np1{sub 1} Rydberg series which lie close to nd2{sub 1} Rydberg states. These observations were analyzed in the framework of multichannel quantum-defect theory. From the observed level shifts, the off-diagonal eigenquantum-defect element ?{sub pd} of singlet-? symmetry was determined to be 0.0023(3) and the corresponding autoionization dynamics could be characterized. The ionization energy of the GK?(v = 1, N = 1) state of HD was determined to be 12?710.544?23(10)?cm{sup ?1}.
Rydberg States of ThIII and UV W. R. Johnson
Johnson, Walter R.
ions, Th3+ and U5+, is a J0 = 5/2 state with a 5f5/2 valence electron outside a Rn-like core. The two valence electron systems of interest here have a Rydberg electron with angular momentum (jkmk) coupled
CH3I low-n Rydberg states in supercritical atomic fluids near the critical point
Findley, Gary L.
critical temperature. A full line shape analysis of these spectra was performed using a single set the same line shapes, although no comparison between the experimental spectra and the simulated line shapesCH3I low-n Rydberg states in supercritical atomic fluids near the critical point Luxi Li a
NO dissociation through ns, np, and nf Rydberg states: Angular distributions
NASA Astrophysics Data System (ADS)
Chen, J.; Strangfeld, B. R.; Houston, P. L.
2014-01-01
Velocity-mapped imaging and theoretical calculations have been used to study the angular distribution of the products of NO predissociation following its excitation to the 11s, 10p, 11p, and 9f Rydberg levels based on the NO+ (X 2?+) core. The Rydberg states were reached from the NO (A 2?+, v = 0, N = 2, J = 1.5) level prepared with strong alignment by excitation with linear polarization from NO (X 2?, v = 0, N = 1, J = 0.5). Ion dip spectra of the Rydberg states were recorded along with velocity-mapped images at the major peaks. The results are compared to calculations based on a previous theoretical approach modified to include transitions to states of Hund's case (d) coupling. The reasonable agreement shows the predictive value of the theory. The theory has also been used to reassess and explain previous results and to understand variations in the rate of photodissociation with components of the 10p and 11p Rydberg states.
Pulsed excitation of Rydberg-atom-pair states in an ultracold Cs gas
Saßmannshausen, Heiner; Deiglmayr, Johannes
2015-01-01
Pulsed laser excitation of a dense ultracold Cs vapor has been used to study the pairwise interactions between Cs atoms excited to $n$p$_{3/2}$ Rydberg states of principal quantum numbers in the range $n=22-36$. Molecular resonances were observed that correspond to excitation of Rydberg-atom-pair states correlated not only to the $n$p$_{3/2}+n$p$_{3/2}$ dissociation asymptotes, but also to $n$s$_{1/2}+(n+1)$s$_{1/2}$, $n$s$_{1/2}+n'$f$_{j}$, and $(n-4)$f$_{j}+(n-3)$f$_{j}$ $(j=5/2,7/2)$ dissociation asymptotes. These pair resonances are interpreted as arising from dipole-dipole, and higher long-range-interaction terms between the Rydberg atoms on the basis of i) their spectral positions, ii) their response to static and pulsed electric fields, and iii) millimeter-wave spectra between pair states correlated to different pair-dissociation asymptotes. The Rydberg-atom--pair states were found to spontaneously decay by Penning ionization and the dynamics of the ionization process were investigated during the first...
Approximate Rydberg States of the Hydrogen Atom that are Concentrated near Kepler Orbits
Hagedorn, George A.
Approximate Rydberg States of the Hydrogen Atom that are Concentrated near Kepler Orbits George A # - 1 |x| . For each Kepler orbit of the corresponding classical system, we construct a lowest order(~)] #(~, Âˇ) # # C ~ 3/2 ##(~, Âˇ)# . The probability density |#(~, x)| 2 is concentrated near the Kepler ellipse
Hróđmarsson, 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?60072?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.
Stephens, J.A.; McKoy, V. (Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125 (United States))
1992-12-01
An {ital ab} {ital initio} electronic structure technique has been developed to study highly excited states of molecules by combining Schwinger variational methods of collision theory with generalized quantum defect theory. The technique exploits methods of scattering theory to study the region of highly excited Rydberg levels below and across ionization thresholds for molecules. The reaction matrix {ital K}, which describes the interaction of the Rydberg electron with the ionic core, is found at arbitrary negative electron energies by employing an unbounded Coulomb Green's function in the Lippmann--Schwinger equation for the electronic wave function. Quantal conditions are imposed to obtain discrete molecular energy levels, associated Rydberg wave functions, and quantum defect functions, all as a function of the internuclear distance. Results within the static-exchange approximation for the {sup 1,3}{Sigma}{sup +}{sub {ital u}}(1{sigma}{sub {ital g}n}{sigma}{sub {ital u}}) and {sup 1,3}{Pi}{sub {ital u}}(1{sigma}{sub {ital g}n}{pi}{sub {ital u}}) Rydberg states of H{sub 2}, for {ital n}=2--20 and {ital R}=1.2--5.0 {ital a}{sub 0}, are presented and discussed.
Wagenaars, E.; Kroesen, G. M. W.; Bowden, M. D.
2006-09-15
Stark effects in Rydberg states of xenon atoms were investigated both experimentally and theoretically. The experimental part consisted of laser-induced fluorescence-dip spectroscopy. Using a (2+1)-photon excitation scheme, xenon atoms were excited from the ground state to high-lying Rydberg ns and nd levels. Measurements were made in a controllable electric field environment, produced by applying a pulsed voltage to two parallel metal electrodes. For energy levels with principal quantum numbers ranging from 12 to 18, Stark shifts of up to 4.8 cm{sup -1} were observed for electric fields ranging from 0 to 4000 V/cm. Additionally, mixing of energy levels in high electric fields was measured for nd levels. The experimental results were compared to a theoretical calculation based on solving the Schroedinger equation for a perturbed Hamiltonian. The calculation method proved to be very accurate for predicting Stark effects in Rydberg nd levels, while for ns levels the agreement was only moderate, probably due to deviations from the assumption of a hydrogenlike atom that is used in the calculation. Finally, the feasibility of using measurements of Stark shifts of Rydberg levels as a diagnostic for electric fields in low-pressure discharges was discussed.
Collisional destruction of circular Rydberg states by atoms with small electron affinities
NASA Astrophysics Data System (ADS)
Mironchuk, Elena S.; Narits, Alexander A.; Lebedev, Vladimir S.
2014-12-01
The results of theoretical studies of interaction between neutral targets with small electron affinities and Rydberg atoms in circular states are reported. The cross sections of collisional destruction of such states due to the resonant quenching mechanism are calculated on the basis of the semiclassical theory of nonadiabatic transitions between the ionic and Rydberg covalent terms of a quasimolecule combined with recently developed technique for exact evaluation of matrix elements. We obtain the basic formula for the square of the coupling parameter involving Rydberg nlm-state with the given values of the principal, orbital, and magnetic quantum numbers. It is employed for the derivation of explicit expressions for transitions from circular states applicable in cases of s- and p-states of negative ion temporarily formed during a collision of atoms. Numerical calculations are carried out for thermal collisions of Li? and Na? atoms with Ca(4s2) and Sr(5s2). We explore n-, l-, m-, and velocity-dependences of the cross sections and analyze orientation effects in such collisions. Cross sections of resonant quenching for circular states (l = | m | = n - 1) are shown to be much smaller than those for states with small l values and typically two times lower than for nearly-circular states (l = n - 1) averaged over m.
Falsaperla, P.; Fonte, G. (Dipartimento di Fisica, Universita di Catania, Corso Italia 57, I-95129 Catania (Italy) Istituto Nazionale di Fisica Nucleare, Sezione di Catania, Corso Italia 57, I-95129 Catania (Italy))
1993-05-01
Applying a method based on some results due to Kato [Proc. Phys. Soc. Jpn. 4, 334 (1949)], we show that series of Rydberg eigenvalues and Rydberg eigenfunctions of hydrogen in a uniform magnetic field can be calculated with a rigorous error estimate. The efficiency of the method decreases as the eigenvalue density increases and as [gamma][ital n][sup 3][r arrow]1, where [gamma] is the magnetic-field strength in units of 2.35[times]10[sup 9] G and [ital n] is the principal quantum number of the unperturbed hydrogenic manifold from which the diamagnetic Rydberg states evolve. Fixing [gamma] at the laboratory value 2[times]10[sup [minus]5] and confining our calculations to the region [gamma][ital n][sup 3][lt]1 (weak-field regime), we obtain extremely accurate results up to states corresponding to the [ital n]=32 manifold.
Radiative decay of helium doubly excited states
NASA Astrophysics Data System (ADS)
Liu, Chien-Nan; Chen, Ming-Keh; Lin, C. D.
2001-07-01
A theoretical study of the radiative decay of low-lying doubly excited 1Po states of Helium in the energy region below the He+(N=2) threshold is presented. We calculated the oscillator strength from the ground state, the Auger and radiative decay rates, and the natural widths of these states. These rates are used to obtain the photon emission and metastable atom yield spectra to compare with experimental measurements, including those from Odling-Smee et al. [Phys. Rev. Lett. 84, 2598 (2000)] and Rubensson et al. [Phys. Rev. Lett. 83, 947 (1999)]. We showed that the lifetimes of the long-lived doubly excited states are determined by the radiative rates.
Radiative decay of helium doubly excited states
Liu, Chien-Nan; Chen, Ming-Keh; Lin, C. D.
2001-07-01
A theoretical study of the radiative decay of low-lying doubly excited {sup 1}P{sup o} states of Helium in the energy region below the He{sup +}(N=2) threshold is presented. We calculated the oscillator strength from the ground state, the Auger and radiative decay rates, and the natural widths of these states. These rates are used to obtain the photon emission and metastable atom yield spectra to compare with experimental measurements, including those from Odling-Smee [Phys. Rev. Lett. 84, 2598 (2000)] and Rubensson [Phys. Rev. Lett. 83, 947 (1999)]. We showed that the lifetimes of the long-lived doubly excited states are determined by the radiative rates.
Radiative Decay of Helium Doubly Excited States
NASA Astrophysics Data System (ADS)
Liu, Chien-Nan; Chen, Ming-Keh; Lin, C. D.
2001-05-01
A theoretical study of the radiative decay of low-lying doubly excited ^1P^o states of Helium in the energy region below the He^+(N=2) threshold is presented. We calculated the oscillator strength from the ground state, the Auger and radiative decay rates, and the natural widths of these states. These rates are used to obtain the photon emission and metastable atom yield spectra to compare with experimental measurements, including those from Odling-Smee et al.(M. K. Odling-Smee, E. Skoell, P. Hammond, and M. A. MacDonald, Phys. Rev. Lett. 84), 2598 (2000). and Rubensson et al.(J.-E. Rubensson, C. Sĺthe, S. Cramm, B. Kessler, S. Stranges, R. Richter, M. Alagia, and M. Coreno, Phys. Rev. Lett. 83), 947 (1999).. We showed that the lifetimes of the long-lived doubly excited states are determined by the radiative rates.
Decay, excitation, and ionization of lithium Rydberg states by blackbody radiation
NASA Astrophysics Data System (ADS)
Ovsiannikov, V. D.; Glukhov, I. L.
2010-09-01
Details of interaction between the blackbody radiation and neutral lithium atoms were studied in the temperature ranges T = 100-2000 K. The rates of thermally induced decays, excitations and ionization were calculated for S-, P- and D-series of Rydberg states in the Fues' model potential approach. The quantitative regularities for the states of the maximal rates of blackbody-radiation-induced processes were determined. Approximation formulas were proposed for analytical representation of the depopulation rates.
Optical spectroscopy of high-L Rydberg states of argon
Wright, L. E.; Snow, E. L.; Lundeen, S. R.; Sturrus, W. G. [Department of Physics, Colorado State University, Fort Collins, Colorado 80523 (United States); Department of Physics, Youngstown State University, Youngstown, Ohio 44555 (United States)
2007-02-15
High-L fine structure patterns in n=9 and n=17 Rydberg levels of argon have been studied using a Doppler-tuned CO{sub 2} laser and a fast beam of argon atoms. Analysis of the measured pattern using the polarization model yields the scalar dipole polarizability and quadrupole moment of the {sup 2}P{sub 3} at {sub {approx}}{sub sol{approx}} at {sub 2} Ar{sup +} ion. The results are {alpha}{sub S}=6.83(8)a{sub 0}{sup 3} and Q=-0.5177(15)ea{sub 0}{sup 2}. Within the precision of this study, no vector component of the structure was observed.
Colombo, Anthony P. (Anthony Paul)
2013-01-01
The chirped-pulse millimeter-wave (CPmmW) technique is applied to transitions between Rydberg states, and calcium atoms are used as the initial test system. The unique feature of Rydberg{Rydberg transitions is that they ...
Colombo, Anthony P.
2013-01-01
We apply the chirped-pulse millimeter-wave (CPmmW) technique to transitions between Rydberg states in calcium atoms. The unique feature of RydbergRydberg transitions is that they have enormous electric dipole transition ...
NASA Astrophysics Data System (ADS)
Konar, Arkaprabha; Shu, Yinan; Levine, Benjamin; Lozovoy, Vadim; Dantus, Marcos
2015-05-01
Here, we report on quantum coherent control of a large (>20 atoms) polyatomic molecule. In particular, we explore the time resolved dynamics of dicyclopentadiene when excited by a pair of phase-locked intense 800nm femtosecond pulses by monitoring changes in ion yield of the parent and fragments. Long-lived oscillations are observed for ~ 500 fs in the parent ion yield indicating the presence of long lived-electronic states. We take advantage of the long-lived electronic coherence to control the yield of different fragment ions. The presence of Rydberg states is further supported by ab initio calculations at the EOM-CCSD/6-31 +G** level of theory which identified five low-lying electronic states of neutral DCPD in the regions between 6.4 and 7.0 eV in vertical excitation energy. States of both pure Rydberg and mixed ? --> ? */Rydberg character are observed in this low energy region and are known to originate from ethylene. The multiphoton excitation of two or more Rydberg states, separated by the photon energy is the key to the observed long-lived electronic coherence in DCPD with a quantum beat at the difference frequency. Rydberg states are expected to have very similar potential energy surfaces and the Rydberg electron is relatively uncoupled to the nuclear dynamics, therefore supporting long electronic coherence time.
Silicon as a model ion trap: Time domain measurements of donor Rydberg states
Vinh, N. Q.; Greenland, P. T.; Litvinenko, K.; Redlich, B.; van der Meer, A. F. G.; Lynch, S. A.; Warner, M.; Stoneham, A. M.; Aeppli, G.; Paul, D. J.; Pidgeon, C. R.; Murdin, B. N.
2008-01-01
One of the great successes of quantum physics is the description of the long-lived Rydberg states of atoms and ions. The Bohr model is equally applicable to donor impurity atoms in semiconductor physics, where the conduction band corresponds to the vacuum, and the loosely bound electron orbiting a singly charged core has a hydrogen-like spectrum according to the usual BohrSommerfeld formula, shifted to the far-infrared because of the small effective mass and high dielectric constant. Manipulation of Rydberg states in free atoms and ions by single and multiphoton processes has been tremendously productive since the development of pulsed visible laser spectroscopy. The analogous manipulations have not been conducted for donor impurities in silicon. Here, we use the FELIX pulsed free electron laser to perform time-domain measurements of the Rydberg state dynamics in phosphorus- and arsenic-doped silicon and we have obtained lifetimes consistent with frequency domain linewidths for isotopically purified silicon. This implies that the dominant decoherence mechanism for excited Rydberg states is lifetime broadening, just as for atoms in ion traps. The experiments are important because they represent a step toward coherent control and manipulation of atomic-like quantum levels in the most common semiconductor and complement magnetic resonance experiments in the literature, which show extraordinarily long spin lattice relaxation timeskey to many well known schemes for quantum computing qubitsfor the same impurities. Our results, taken together with the magnetic resonance data and progress in precise placement of single impurities, suggest that doped silicon, the basis for modern microelectronics, is also a model ion trap.
Asymptotics of $L_p$-norms of Hermite polynomials and Rényi entropy of Rydberg oscillator states
Alexander I. Aptekarev; Jesús S. Dehesa; Pablo Sánchez-Moreno; Dmitrii N. Tulyakov
2013-05-14
The asymptotics of the weighted $L_{p}$-norms of Hermite polynomials, which describes the R\\'enyi entropy of order $p$ of the associated quantum oscillator probability density, is determined for $n\\to\\infty$ and $p>0$. Then, it is applied to the calculation of the R\\'enyi entropy of the quantum-mechanical probability density of the highly-excited (Rydberg) states of the isotropic oscillator.
NASA Astrophysics Data System (ADS)
Donovan, Robert J.; Lawley, Kenneth P.; Ridley, Trevor
2015-05-01
We report the identification of heavy Rydberg resonances in the ion-pair spectra of I2, Cl2, ICl, and IBr. Extensive vibrational progressions are analysed in terms of the energy dependence of the quantum defect ?(Eb) rather than as Dunham expansions. This is shown to define the heavy Rydberg region, providing a more revealing fit to the data with fewer coefficients and leads just as easily to numbering data sets separated by gaps in the observed vibrational progressions. Interaction of heavy Rydberg states with electronic Rydberg states at avoided crossings on the inner wall of the ion-pair potential is shown to produce distinctive changes in the energy dependence of ?(Eb), with weak and strong interactions readily distinguished. Heavy Rydberg behaviour is found to extend well below near-dissociation states, down to vibrational levels 18 000-20 000 cm-1 below dissociation. The rapid semi-classical calculation of ?(Eb) for heavy Rydberg states is emphasised and shows their absolute magnitude to be essentially the volume of phase space excluded from the vibrational motion by avoiding core-core penetration of the ions.
Donovan, Robert J; Lawley, Kenneth P; Ridley, Trevor
2015-05-28
We report the identification of heavy Rydberg resonances in the ion-pair spectra of I2, Cl2, ICl, and IBr. Extensive vibrational progressions are analysed in terms of the energy dependence of the quantum defect ?(Eb) rather than as Dunham expansions. This is shown to define the heavy Rydberg region, providing a more revealing fit to the data with fewer coefficients and leads just as easily to numbering data sets separated by gaps in the observed vibrational progressions. Interaction of heavy Rydberg states with electronic Rydberg states at avoided crossings on the inner wall of the ion-pair potential is shown to produce distinctive changes in the energy dependence of ?(Eb), with weak and strong interactions readily distinguished. Heavy Rydberg behaviour is found to extend well below near-dissociation states, down to vibrational levels ?18,000-20,000 cm(-1) below dissociation. The rapid semi-classical calculation of ?(Eb) for heavy Rydberg states is emphasised and shows their absolute magnitude to be essentially the volume of phase space excluded from the vibrational motion by avoiding core-core penetration of the ions. PMID:26026446
Half-cycle-pulse-train induced state redistribution of Rydberg atoms
Mandal, P. K.; Speck, A. [Rowland Institute at Harvard, Cambridge, Massachusetts 02142 (United States)
2010-01-15
Population transfer between low-lying Rydberg states independent of the initial state is realized using a train of half-cycle pulses with pulse durations much shorter than the classical orbital period. We demonstrate experimentally the population transfer from initial states around n=50 with 10% of the population de-excited down to n<40 as well as up to the continuum. This is a demonstration of a state-independent de-excitation technique applicable to the currently produced state distribution of antihydrogen. The measured population transfer matches well to a model of the process for one-dimensional atoms.
Rydberg series of 1?u+ and 1?u states of the Li2 molecule studied by the promotion model
NASA Astrophysics Data System (ADS)
Kim, Hyun-Jin; Lee, Chun-Woo
2015-01-01
We studied the Rydberg series for the 12 1?u+, 7 1?u, and 1 1?u states. This set consists of the seventeen states derivable from the Li(2s) + Li(nl) (n = 2, 3, 4, 5) configuration, one 1?u+ state and one 1?u state derivable from Li(2s) + Li(6p) and Li(2s) + Li(6d), respectively, plus one ionic state. We used the multireference configuration interaction method, combined with the Stuttgart/Köln groups effective core potential/core polarization potential method, to calculate their potential energy curves (PECs). Four Rydberg series, ?uns (n = 3, 4, 5, 6), ?unp (n = 2, 3, 4, 5), ?und (n = 3, 4, 5, 6), and ?unf (n = 4, 5), are identified near the potential energy minima (referred to as the Rydberg region). The promotion model is used to examine the behaviour of PECs and quantum defect curves (QDCs) by constructing diabatic PECs and QDCs. Besides QDCs, effective n and promotion curves are also used to directly examine the promotion. This reveals that the promotion model can be successfully applied to the singlet ungerade states of Li2, indicating that the Rydberg region has the same characteristics as the united atom (UA) limit. Thus, the Rydberg region in Li2 is much closer to the UA limit than the separated atoms (SA) limit. Correlation diagrams based on the promotion model show a big difference in the number of avoided crossings for the 1?u+ and 1?u states. The larger number of avoided crossings for 1?u+ states produces features in the PECs of the 1?u+ states such as shoulders, flattening, and grouping. The promotion model not only helps to identify Rydberg series, but also to explain all the major and minor aspects and subtle phenomena observed in the PECs and spectroscopic constants of the singlet ungerade Rydberg states of Li2.
NASA Astrophysics Data System (ADS)
Huismans, Y.; Rouzée, A.; Gijsbertsen, A.; Logman, P. S. W. M.; Lépine, F.; Cauchy, C.; Zamith, S.; Stodolna, A. S.; Jungmann, J. H.; Bakker, J. M.; Berden, G.; Redlich, B.; van der Meer, A. F. G.; Schafer, K. J.; Vrakking, M. J. J.
2013-03-01
Angle-resolved photoelectron spectra, resulting from the strong-field ionization of atoms or molecules, carry a rich amount of information on ionization pathways, electron dynamics, and the target structure. We have investigated angle-resolved photoelectron spectra arising from the nonresonant ionization of xenon Rydberg atoms in the multiphoton regime, using intense midinfrared radiation from a free-electron laser. The experimental data reveal a rich oscillatory structure in the low-order above-threshold ionization region. By performing quantum-mechanical and semiclassical calculations, the observed oscillations could be well reproduced and explained by both a multiphoton absorption picture as by a model invoking electron wave-packet interferences. Furthermore, we demonstrate that the shape and orientation of the initial Rydberg state leaves its own fingerprint on the final angular distribution.
The role of optical transitions between ionic and Rydberg states in a KrF laser
Datsyuk, V V [Department of Physics and Mathematics, T.G. Shevchenko Pridnestrie State University (Moldova, Republic of)
2001-05-31
The upper laser level of a KrF laser is treated as a cluster containing several hundreds vibration-rotation energy levels of the electronic state B, which is mixed due to collisions with the close ionic state C. The KrF (C) state is depleted as a result of optical transitions to a higher Rydberg state. This model explains the experimental data on the picosecond dynamics of the light amplification. The possibility of using a KrF laser as an amplifier of radiation with a wavelength of 120 nm is discussed. (lasers and amplifiers)
Spectroscopic Observation and Characterization of H+H- Heavy Rydberg States
NASA Astrophysics Data System (ADS)
Vieitez, M. O.; Ivanov, T. I.; Reinhold, E.; de Lange, C. A.; Ubachs, W.
2009-07-01
A series of discrete resonances was observed in the spectrum of H2, which can be unambiguously assigned to bound quantum states in the 1/R Coulombic potential of the H+H- ion-pair system. Two-step laser excitation was performed, using tunable extreme ultraviolet radiation at ? = 94-96 nm in the first step, and tunable ultraviolet radiation in the range ? = 310-350 nm in the second step. The resonances, detected via H+ and H2+ ions produced in the decay process, follow a sequence of principal quantum numbers (n = 140-230) associated with a Rydberg formula in which the Rydberg constant is mass scaled. The series converges upon the ionic H+H- dissociation threshold. This limit can be calculated without further assumptions from known ionization and dissociation energies in the hydrogen system and the electronegativity of the hydrogen atom. A possible excitation mechanism is discussed in terms of a complex resonance. Detailed measurements are performed to unravel and quantify the decay of the heavy Rydberg states into molecular H2+ ions, as well as into atomic fragments, both H(n = 2) and H(n = 3). Lifetimes are found to scale as n3.
Spectroscopic observation and characterization of H(+)H(-) heavy Rydberg states.
Vieitez, M O; Ivanov, T I; Reinhold, E; de Lange, C A; Ubachs, W
2009-11-26
A series of discrete resonances was observed in the spectrum of H2, which can be unambiguously assigned to bound quantum states in the 1/R Coulombic potential of the H+H- ion-pair system. Two-step laser excitation was performed, using tunable extreme ultraviolet radiation at lambda = 94-96 nm in the first step, and tunable ultraviolet radiation in the range lambda = 310-350 nm in the second step. The resonances, detected via H+ and H2+ ions produced in the decay process, follow a sequence of principal quantum numbers (n = 140-230) associated with a Rydberg formula in which the Rydberg constant is mass scaled. The series converges upon the ionic H+H- dissociation threshold. This limit can be calculated without further assumptions from known ionization and dissociation energies in the hydrogen system and the electronegativity of the hydrogen atom. A possible excitation mechanism is discussed in terms of a complex resonance. Detailed measurements are performed to unravel and quantify the decay of the heavy Rydberg states into molecular H2+ ions, as well as into atomic fragments, both H(n = 2) and H(n = 3). Lifetimes are found to scale as n3. PMID:19921940
Keller, Ursula
that the fraction of Rydberg states (excited neutral atoms) created by tunnel ionization declines dramaticallyRydberg state creation by tunnel ionization This article has been downloaded from IOPscience state creation by tunnel ionization A S Landsman1 , A N Pfeiffer, C Hofmann, M Smolarski, C Cirelli
Photoelectron spectroscopy of the linear (Ă 2A 1)3pb 21B 2 Rydberg state of water
NASA Astrophysics Data System (ADS)
Pratt, S. T.; Dehmer, J. L.; Dehmer, P. M.
1992-08-01
Photoelectron spectra are reported for two-photon-resonant, three-photon ionization via several vibrational levels of the linear (Ă 2A 1)3pb 21B 2 Rydberg state of H 2O and D 2O. In the dominant photoionization pathway, the ejection of the Rydberg electron occurs with no change in the electronic or vibrational state of the ion core, providing direct confirmation of the vibrational numbering of the 1B 2 state proposed by Abramson et al. Photoionization accompanied by excitation of the symmetric stretch in the resulting ion is also observed, reflecting the difference in bond lengths between the 1B 2 Rydberg state and the Ă 2A 1 ionic state.
Komninos, Yannis; Nicolaides, Cleanthes A.
2005-09-15
We consider problems of short-time dynamics of a polyelectronic atomic nonstationary state, V, assumed to be formed as a wave packet at t=0. We focus on two cases, for which the role of the quasicontinuum of the upper part of the Rydberg states, with which the V state has nonzero coupling matrix elements, is investigated. In the first case, the position of the V state is just above the ionization threshold, E=0, and so V dissipates into the free electron continuum as an autoionizing state. The question is how the presence of the Rydberg series converging to E=0 affects the time evolution of the autoionizing V. In the second case, the position of V is embedded in the quasicontinuum of the Rydberg series below threshold. The question is whether there are distinct features in the time evolution of this V, although its position is in the discrete part of the energy spectrum. In this case, by focusing on short times and by evaluating analytically certain infinite sums, analogous to Fourier integrations, the following result is obtained: For small times, the V state evolves as an exponentially decaying state. However, in addition to the term describing exponential decay, there is a term, entering with a small coefficient, which describes exponential growth and eventually dominates. It is shown that exponential decay holds for times shorter than the time t{sub p} needed by the wave packet to reach the outer classical turning point. For the decay to be physically meaningful, this time must be smaller than the time t{sub d} which equals the inverse of the half-width in atomic units. We examined a model system of V-Rydberg state interaction based on the Boron {sup 2}S spectrum. The results indicate that the effect is observable on the scale of femtoseconds.
Cardoza, Job D.; Rudakov, Fedor M.; Weber, Peter M.
2009-01-01
Resonance-enhanced multiphoton ionization photoelectron spectroscopy has been applied to study the electronic spectroscopy and relaxation pathways amongst the 3p and 3s Rydberg states of trimethylamine. The experiments used femtosecond and picosecond duration laser pulses at wavelengths of 416 nm, 266 nm, and 208 nm, and employed two-photon and three-photon ionization schemes. The binding energy of the 3s Rydberg state was found to be 3.087 ą 0.005 eV. The degenerate 3px,y states have binding energies of 2.251 ą 0.005 eV, and 3pz is at 2.204 ą 0.005 eV. Using picosecond and femtosecond time-resolved experiments we spectrally and temporally resolved an intricate sequence of energy relaxation pathways leading from the 3p states to the 3s state. With excitation at 5.96 eV, trimethylamine is found to decay from the 3pz state to 3px,y in 539 fs. The decay to 3s from all the 3p states takes place with a 2.9 ps time constant. On these time scales, trimethylamine does not fragment at the given internal energies, which range from 0.42 to 1.54 eV depending on the excitation wavelength and the electronic state. PMID:18834091
Density effects on high-n molecular Rydberg states: CH3I in argon
NASA Astrophysics Data System (ADS)
Köhler, A. M.; Reininger, R.; Saile, V.; Findley, G. L.
1986-01-01
Absorption spectra of the high-n molecular Rydberg states of CH3I, perturbed by varying number densities of argon (up to ~11×1020 cm-3), are reported. Red shifts, which increase with increasing argon number density, are observed for both discrete and autoionizing states. These red shifts vary linearly with the perturber number density for principal quantum numbers n>=10. We explain these results quantitatively on the basis of the electron scattering length in argon, as well as the polarization of the medium by CH3I+.
Ni, Y; Martin, J D D
2015-01-01
Non-resonant dressing fields can make the transition frequency between two circular Rydberg states insensitive to second order variations in the dc electric field. Perturbation theory can be used to establish the required dressing field amplitude and frequency. The same perturbative approach may be used to understand removal of the first order dependence of the transition frequency on electric field about a bias dc electric field [Hyafil et al. Phys. Rev. Lett., v. 93, 103001 (2004)]. The directional alignment of the dressing and dc fields is critical in determining the electric field sensitivity of the dressed transition frequencies. This sensitivity is significantly larger for circular Rydberg states compared to low-angular momentum Rydberg states of Rb.
Time-resolved photoionization spectroscopy of mixed Rydberg-valence states: indole case study.
Zawadzki, Magdalena M; Thompson, James O F; Burgess, Emma A; Paterson, Martin J; Townsend, Dave
2015-10-28
Time-resolved photoelectron imaging was used to study non-adiabatic relaxation dynamics in gas-phase indole following photo-excitation at 267 nm and 258 nm. Our data analysis was supported by various ab initio calculations using both coupled cluster and density functional methods. The highly differential energy- and angle-resolved information provided by our experimental approach provides extremely subtle details of the complex interactions occurring between several low-lying electronically excited states. In particular, new insight into the role and fate of the mixed Rydberg-valence 3s/??* state is revealed. This includes population residing on the excited state surface at large N-H separations for a relatively long period of time (?1 ps) prior to dissociation and/or internal conversion. Our findings may, in part, be rationalized by considering the rapid evolution of this state's electronic character as the N-H stretching coordinate is extended - as extensively demonstrated in the supporting theory. Overall, our findings highlight a number of important general caveats regarding the nature of mixed Rydberg-valence excited states, their spectral signatures and detection sensitivity in photoionization measurements, and the evaluation of their overall importance in mediating electronic relaxation in a wide range of small model-chromophore systems providing bio-molecular analogues - a topic of considerable interest within the chemical dynamics community over the last decade. PMID:26394263
NASA Astrophysics Data System (ADS)
Zeng, De-Ling; Gao, Xiang; Han, Xiao-Ying; Li, Jia-Ming
2015-02-01
Low-energy electron-impact cross sections of helium among the ground and some low excited states are calculated using the R -matrix method. The convergences of the cross sections are checked systematically by using five sets of high-quality target states; i.e., including 5, 11, 19, 29, and 39 physical target states, respectively. Our calculated cross sections are in excellent agreement with the benchmark high-resolution experimental data. Compared with the recommended theoretical data, there is a deviation of about 6%, which suggests the recommended data may need a revision. Based on our calculation results, the influence of the Rydberg target states on the collision cross sections of the excited states is found to be similar to the case of the ground state; i.e., the amplitude of resonance structures will decrease with respect to the principal quantum number n of Rydberg target states. This result should be very useful for providing the cross-section data in the whole energy regions with high quality, which would be of great importance in related scientific fields.
Evolution of Rydberg states in half-cycle pulses: Classical, semiclassical, and quantum dynamics
Burgdoerfer, J.; Reinhold, C. [Tennessee Univ., Knoxville, TN (United States). Dept. of Physics]|[Oak Ridge National Lab., TN (United States)
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.
Vogt, Thibault; Viteau, Matthieu; Zhao Jianming; Chotia, Amodsen; Comparat, Daniel; Pillet, Pierre [Laboratoire Aime Cotton, CNRS, Batiment 505, Campus d'Orsay, 91405 Orsay (France)
2006-08-25
High resolution laser excitation of np Rydberg states of cesium atoms shows a dipole blockade at Foerster resonances corresponding to the resonant dipole-dipole energy transfer of the np+np{yields}ns+(n+1)s reaction. The dipole-dipole interaction can be tuned on and off by the Stark effect, and such a process, observed for relatively low n(25-41), is promising for quantum gate devices. Both Penning ionization and saturation in the laser excitation can limit the range of observation of the dipole blockade.
NASA Astrophysics Data System (ADS)
Zhelyazkova, V.; Hogan, S. D.
2015-07-01
Dipole-dipole interactions between helium atoms in Rydberg-Stark states with principal quantum number n =53 and approximately linear Stark energy shifts, resulting from induced electric dipole moments of approximately 7900 D, have been investigated experimentally. The experiments were performed in pulsed supersonic metastable helium beams, with particle number densities of up to 109cm-3 . In the presence of amplitude-modulated, radio-frequency electric fields, changes in the spectral intensity distributions associated with the transitions to these states that are attributed to dipole-dipole interactions within the ensembles of excited atoms have been observed. The experimental results are in excellent agreement with calculations of the Rydberg energy level structure carried out using Floquet methods, and excitations shared by up to four atoms. The use of these Rydberg-Stark states as sensors for nonresonant broadband radio-frequency electrical noise is also discussed.
Zhelyazkova, V
2015-01-01
Dipole-dipole interactions between helium atoms in Rydberg-Stark states with principal quantum number $n=53$ and approximately linear Stark energy shifts, resulting from induced electric dipole moments of approximately 7900 D, have been investigated experimentally. The experiments were performed in pulsed supersonic metastable helium beams, with particle number densities of up to $\\sim10^9$ cm$^{-3}$. In the presence of amplitude-modulated, radio-frequency electric fields, changes in the spectral intensity distributions associated with the transitions to these states that are attributed to dipole-dipole interactions within the ensembles of excited atoms have been observed. The experimental results are in excellent agreement with calculations of the Rydberg energy level structure carried out using Floquet methods, and excitations shared by up to 4 atoms. The use of these Rydberg-Stark states as sensors for non-resonant broadband radio-frequency electrical noise is also discussed.
NASA Astrophysics Data System (ADS)
Dewangan, D. P.; Neerja; Basuchoudhury, K.
2005-04-01
The paper presents a new alternative exact quantum expression of the x-component of the dipole matrix element between the Stark states of a hydrogen atom in terms of the Jacobi polynomials by transforming the hypergeometric functions appearing in the standard quantum formula. The new quantum formula readily leads to analytic study and numerical computation for such large values of the parabolic quantum numbers for which difficulties had earlier been encountered. The paper goes on to derive an approximate but simple quantum formula of the dipole matrix element in terms of the ordinary Bessel functions and demonstrates its remarkable accuracy for transitions ranging from that between the Stark levels of the lowest lying states to that between the Stark levels of nearby Rydberg states. The formula enables accurate numerical computation to be performed over an extended range of large parabolic quantum numbers that had earlier defied evaluation. The expressions given in this paper in essence solve the problem of determination of analytic behaviour and numerical computation of the dipole matrix element for transitions between the Stark levels of nearby Rydberg states. The paper also presents, for the first time, a derivation of the formula of the correspondence principle method from the quantum expression without appealing to any classical or semiclassical argument, and clarifies the conditions of its applicability.
Spin squeezing and Schrödinger-cat-state generation in atomic samples with Rydberg blockade
NASA Astrophysics Data System (ADS)
Opatrný, Tomá; Mřlmer, Klaus
2012-08-01
A scheme is proposed to prepare squeezed states and Schrödinger-cat-like states of the collective spin degrees of freedom associated with a pair of ground states in an atomic ensemble. The scheme uses an effective Jaynes-Cummings interaction which can be provided by excitation of the atoms to Rydberg states and an effective Jx interaction implemented by a resonant Raman coupling between the atomic ground states. Dynamical evolution both with a constant Hamiltonian and with adiabatic variation of the two interaction terms is studied. We show that by the application of further resonant laser fields, we can suppress nonadiabatic transfer under the time-varying Hamiltonian and significantly speed up the evolution towards a maximally squeezed, Jz=0, collective spin state.
Photoionization, photodissociation, and long-range bond formation in molecular Rydberg states
NASA Astrophysics Data System (ADS)
Hamilton, Edward Lees
2003-10-01
The Rydberg spectra of atoms and small molecules offers an experimentally convenient probe for exploring the exchange of energy between Rydberg electrons and other forms of electronic, vibrational, and rotational excitation. This thesis investigates a series of special topics in the field of molecular Rydberg spectra, using a diverse set of theoretical techniques all designed to take advantage of the computational efficiency of the sorts of scattering parameterizations commonly associated with the field of quantum defect theory. In particular. I consider various mechanisms by which Rydberg electrons participate in the formation (bonding) and destruction (dissociation) of molecular states. First, I review the methodology of multichannel quantum defect theory in molecular systems, demonstrating its versatility in reducing a complicated set of channel-coupled solutions into a physically observable photoionization spectrum with exceptionally high resolution, even in regions characterized by complex resonant structures with strong energy dependence. The utility of the Fano frame transformation is discussed, two approaches to the problem of extracting resonant effects via the delay of asymptotic boundary conditions are presented, and a case study featuring the molecular hydrogen isotopomer HD is examined in detail. Second, I turn to the question of Rydberg electrons in the presence of both an ionic core and a neutral perturbing particle, extending certain basic features of the above philosophy to a two-center geometry. This system is predicted to give rise to a potential well that supports bound states, with a potential curve minimum existing at many hundreds or thousands of Bohr radii. The problem is first handled at the level of a zero-range potential approximation, where the solution can be written by means of degenerate perturbation theory. This approach is compared to a more robust, but computationally expensive; description of the interaction in terms of a finite range model potential, requiring diagonalization of the Hamiltonian with respect to an L2 basis. Some properties of these states are also noted. Next, a more powerful but difficult formulation using the Coulomb Green's function; subject to limiting boundary conditions at the position of the core and perturber, is derived. Finally, a semiclassical interpretation, corresponding to the trajectories of a point particle electron moving classically in a Coulombic field, is examined in detail. Third, I return to the case of the diatomic Rydberg spectrum, this time extending the solution to accommodate dissociation pathways through the use of a Siegert pseudostate basis. Previously developed methods of treating the competition between ionization and dissociation are reviewed and evaluated. The Siegert basis is defined, together with an efficient procedure for its calculation, and some of its unconventional properties are explicitly noted. The Siegert-MQDT method is applied to several reactive scattering or half-scattering processes, including photodissociation, dissociative ionization, and dissociative recombination.
NASA Astrophysics Data System (ADS)
Long, Jingming; HróĂ°marsson, Helgi Rafn; Wang, Huasheng; Kvaran, Ágúst
2012-06-01
Mass spectra were recorded for one-colour resonance enhanced multiphoton ionization (REMPI) of HiBr (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 F1?2(v' = 1) and V1?+(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 E1?+ (v' = 1) and H1?+(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 k3?0(v' = 0) ?? X transition with band origin 80 038 cm-1 and rotational parameter B_{v^' } = 7.238cm^{ - 1}.
Field-ionization processes in high Rydberg states of Rb under a rotating electric field
Yamada, S.; Funahashi, H.; Shibata, M.; Kominato, K.; Kishimoto, Y.; Tada, M.; Haseyama, T.; Ogawa, I.; Matsuki, S.; Yamamoto, K. [Department of Physics, Kyoto University, Kita-Shirakawa, Sakyo-ku, Kyoto 606-8503 (Japan); Nuclear Science Division, Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Department of Nuclear Engineering, Kyoto University, Yoshida, Sakyo, Kyoto 606-8501 (Japan)
2005-09-15
Field ionization of high Rydberg manifold states (n=112-137) of rubidium-85 under a rotating electric field has been investigated experimentally and theoretically. Applying a rapidly reversed electric field with a small static perpendicular field to rotate the total electric field around zero, we have observed substantial increase of the fraction of the tunneling field-ionization process and a profound broadening of its ionization peak over a wide range of field strengths with increasing transverse electric field. The observed tunneling field-ionization fraction is almost independent of the slew rate of the applied electric field, and also on the principal quantum number n over the range investigated. To compare with these experimental results, theoretical calculations have been performed with a successive two-step regime. As the first step we calculated the redistributions of magnetic quantum number m{sub l} and parabolic quantum number n{sub 1}-n{sub 2} of the states under the rotating electric field. Then the following time evolution of the manifold states with |m{sub l}|{<=}3 was traced on the Stark map in a coherent as well as an incoherent model. The calculated results are generally in good agreement with the experimental ones. The increase of the tunneling field-ionization fraction under a rotating electric field plays an essential role in achieving the high efficiency in the recently proposed selective-field-ionization scheme for high Rydberg atoms.
Many-Body Spin Interactions and the Ground State of a Dense Rydberg Lattice Gas
Lesanovsky, Igor [Midlands Ultracold Atom Research Centre (MUARC), School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD (United Kingdom)
2011-01-14
We study a one-dimensional atomic lattice gas in which Rydberg atoms are excited by a laser and whose external dynamics is frozen. We identify a parameter regime in which the Hamiltonian is well approximated by a spin Hamiltonian with quasilocal many-body interactions which possesses an exact analytic ground state solution. This state is a superposition of all states of the system that are compatible with an interaction induced constraint weighted by a fugacity. We perform a detailed analysis of this state which exhibits a crossover between a paramagnetic phase with short-ranged correlations and a crystal. This study also leads us to a class of spin models with many-body interactions that permit an analytic ground state solution.
Atomic parameters for transitions involving Rydberg states of singly ionized alkaline earths
NASA Astrophysics Data System (ADS)
Tahar Djerad, Mohamed
1991-01-01
Using quantum-defect theory wave functions, we have computed dipole radial matrix elements involving Rydberg states of the singly-ionized alkaline-earth atoms. In order to test the results, we have calculated a set of transition probabilities, absorption oscillator strengths and radiative lifetimes for S, P, D, and F states up to n sim 30. Transition probabilities are in good agreement with available data. We report the lifetimes in terms of scaling relations of type tau_{nl}=tau_0(n^*)^?. The variation of oscillator strengths with respect to the effective principal quantum number n^* is discussed. En utilisant des fonctions d'onde de la théorie du défaut quantique, nous avons calculé les éléments de matrice radiaux mettant en jeu les états de Rydberg des atomes alcalineux terreux une fois ionisés. Dans le but de tester les résultats, nous avons calculé les probabilités de transitions, les forces d'oscillateurs et les durées de vie radiative des états S, P, D et F jusqu'ŕ n sim 30. Les probabilités de transitions sont en bon accord avec les résultats disponibles. Nous présentons les durées de vie en terme de lois d'échelles du type tau_{nl}=tau_0(n^*)^?. La variation des forces d'oscillateurs en fonction du nombre quantique effectif n^* est discutée.
Many-body physics of Rydberg dark-state polaritons in the strongly interacting regime
Matthias Moos; Michael Hoening; Razmik Unanyan; Michael Fleischhauer
2015-06-23
Coupling light to Rydberg states of atoms under conditions of electromagnetically induced transparency (EIT) leads to the formation of strongly interacting quasi-particles, termed Rydberg polaritons. We derive a one-dimensional model describing the time evolution of these polaritons under paraxial propagation conditions, which we verify by numerical two-excitation simulations. We determine conditions allowing for a description by an effective Hamiltonian of a single-species polariton, and calculate ground-state correlations by use of the density matrix renormalization group (DMRG). Under typical stationary slow-light EIT conditions it is difficult to reach the strongly interacting regime where the interaction energy dominates the kinetic energy. We show that by employing time dependence of the control field the regime of strong interactions can be reached where the polaritons attain quasi crystalline order. We analyze the dynamics and resulting correlations for a translational invariant system in terms of a time-dependent Luttinger liquid theory and exact few-particle simulations and address the effects of nonadiabatic corrections and initial excitations.
An Ordered State of Dislocations in Solid Helium
NASA Astrophysics Data System (ADS)
Lauter, Hans Jochen; Krotscheck, Eckhard; Kats, Efim; Herwig, Kenneth; Podlesnyak, Andrey; Souleymane, Diallo; Henry, Glyde; Savici, Andreii
2013-03-01
An ordered state of dislocations, see e.g., is disclosed from neutron inelastic scattering data taken from solid helium at 40mK and a pressure of about 30bar. A characteristic feature is the phonon gap at the origin of about 0.15 meV, which reveals the non-equilibrium state of stressed helium created by rapid cooling with the blocked-capillary method. Energy gain scattering starts to appear at a temperature of 0.5 K that underlines the non-equilibrium state of stressed helium and the non-applicability of the detailed balance. The increasing thermal occupation of phonon-states observed as increasing intensity in energy gain scattering builds to a phase transition close to 1.4K. The creation of a helium single crystal with hcp-structure in thermal equilibrium is observed at this temperature. This phase transition is in agreement with the vanishing quasi two-dimensional superfluid helium in solid helium confined in aerogel around 1.3K. The event of the ``supersolid'' transition around 100mK is not observed in the two neutron scattering experiments.
Rydberg states of the hydrogen-antihydrogen quasimolecule
Sharipov, V. [Institute of Physics, St. Petersburg State University, 198904, Uljanovskaya 1, Petrodvorets, St. Petersburg (Russian Federation); Labzowsky, L. [Institute of Physics, St. Petersburg State University, 198904, Uljanovskaya 1, Petrodvorets, St. Petersburg (Russian Federation); Petersburg Nuclear Physics Institute, 188350, Gatchina, St. Petersburg (Russian Federation); Max-Planck Institut fuer Physik komplexer Systeme, Noethnitzerstrasse 38, D-01187 Dresden (Germany); Plunien, G. [Technische Universitaet Dresden, Mommsenstrasse 13, D-01062, Dresden (Germany)
2006-05-15
A description of the excited lepton states of the hydrogen-antihydrogen quasimolecule is presented. Potential energy curves and the leptonic part of the wave functions corresponding to a variety of such states are calculated within the Born-Oppenheimer approximation employing the Ritz variational principle. Nonadiabatic corrections to the leptonic potentials are also obtained. Basis functions are constructed as products of explicitly correlated Gaussians and spherical harmonics which describe correctly the motion of leptons with arbitrary orbital angular momentum projection onto the molecular (internuclear) axis. The hadronic part of the wave function for each leptonic level of the hydrogen-antihydrogen system is calculated by solving the Schroedinger equation with the obtained leptonic potentials. Corresponding solutions are generated utilizing precise B-spline representations. Employing leptonic and hadronic parts of the wave function the electron-positron and proton-antiproton annihilation rates are computed for a number of quasimolecular states. The decay rates of the hydrogen-antihydrogen system into separate positronium and protonium atoms are also estimated for the quasimolecular levels under consideration.
Velocity-selective EIT measurement of potassium Rydberg states
Xu, Wenchao
2015-01-01
We demonstrate a velocity selection scheme that mitigates suppression of electromagnetically induced transparency (EIT) by Doppler shifts for low--high EIT probe--coupling wavelength ordering. An optical pumping beam counter-propagating with the EIT probe beam transfers atoms between hyperfine states in a velocity selective fashion. Measurement of the transmitted probe beam synchronous with chopping of the optical pumping beam enables a Doppler-free EIT signal to be detected. Transition frequencies between 5P$_{1/2}$ and $n$S$_{1/2}$ states for $n=$26, 27, and 28 in $^{39}$K are obtained via EIT spectroscopy in a heated vapor cell with a probe beam stabilized to the 4S$_{1/2}\\rightarrow$5P$_{1/2}$ transition. Using previous high-resolution measurements of the 4S$_{1/2}\\rightarrow$nS$_{1/2}$ transitions, we make a determination of the absolute frequency of the 4S$_{1/2}\\rightarrow$5P$_{1/2}$ transition. Our measurement is shifted by 560 MHz from the currently accepted value with a two-fold improvement in uncer...
Dissociation dynamics of high-v Rydberg states of molecular hydrogen
NASA Astrophysics Data System (ADS)
McCormack, E. F.; Pratt, S. T.; Dehmer, P. M.; Dehmer, J. L.
1993-06-01
The dynamics of the decay of (Chi 2Sigma(+) sub g)n,p, v-prime of 9 or greater Rydberg states of H2 into the H(1s) + H(3l) and H(1s) + H(4l) dissociation continua are investigated by examining the dissociation spectrum of H2 in the energy region between the H(1s) + H(4l) dissociation threshold and the Chi 2Sigma(+) sub g, v(+) = 9 ionization threshold, using a double resonance excitation scheme via the E,F 1Sigma(+) sub g, v = 6 state. A comparison of this spectrum to the previously observed Chi 2Sigma(+) sub g, v(+) = 8 constant-ionic-state photoelectron spectrum and the ion-pair spectrum observed in the same energy region reveal strong competition between the ionization and dissociation processes through both rovibrational and electronic interactions.
Explicitly correlated Gaussian calculations of the {sup 2}D Rydberg states of the boron atom
Sharkey, Keeper L.; Bubin, Sergiy; Adamowicz, Ludwik
2012-08-14
Accurate non-relativistic variational calculations are performed for the seven lowest members of the {sup 2}D Rydberg series (1s{sup 2}2s2p{sup 2}, and 1s{sup 2}2s{sup 2}nd, n= 3, Horizontal-Ellipsis , 8) of the boron atom. The wave functions of the states are expanded in terms of all-electron explicitly correlated Gaussian basis functions and the effect of the finite nuclear mass is directly included in the calculations allowing for determining the isotopic shifts of the energy levels. The Gaussian basis is optimized independently for each state with the aid of the analytic energy gradient with respect to the Gaussian parameters. The calculations represent the highest accuracy level currently achievable for the considered states. The computed energies are compared with the available experimental data.
Bartsch, T.; Schippers, S.; Mueller, A.; Brandau, C.; Gwinner, G.; Saghiri, A.A.; Beutelspacher, M.; Grieser, M.; Schwalm, D.; Wolf, A.; Danared, H.; Dunn, G.H.
1999-05-01
We report the first experimental observation of magnetic field effects on dielectronic recombination (DR) via highly excited Rydberg levels. Crossed static electric and magnetic fields E{sub y} and B{sub z} were imposed on the collision region in high resolution DR measurements with Li-like Cl{sup 14+} ions at the heavy ion storage ring TSR in Heidelberg. Enhancement of DR rate coefficients {alpha} for the group of high Rydberg states attached to the 2p{sub 1/2} and 2p{sub 3/2} series limits was observed when motional electric fields E{sub y} up to 380thinspthinspV/cm were introduced. The associated enhancement rate d{alpha}/dE{sub y} which we found to be constant at least for E{sub y}{le}100 V/cm decreased by almost a factor of 2 when the longitudinal field B{sub z} was increased from 20 to 69thinspthinspmT. {copyright} {ital 1999} {ital The American Physical Society}
Yang, Xueliang; Zhou, Jingang; Jones, Brant; Ng, C Y; Jackson, William M
2008-02-28
The photoionization efficiency (PIE) spectra of metastable sulfur (S) atoms in the 1 D and 1 S states have been recorded in the 73 350-84 950 cm(-1) frequency range by using a velocity-mapped ion imaging apparatus that uses a tunable vacuum ultraviolet laser as the ionization source. The S(1 D) and S(1 S) atoms are produced by the 193 nm photodissociation of CS2. The observed PIE spectra of S(1 D) and S(1 S) shows 35 autoionizing resonances with little or no contribution from direct photoionization into the S+(4S 3/2)+e(-) ionization continuum. Velocity-mapped ion images of the S+ at the individual autoionizing Rydberg resonances are used to distinguish whether the lower state of the resonance originates from the 1 D, 1 S, or 3P states. The analysis and assignment of the Rydberg peaks revealed 22 new Rydberg states that were not previously known. The autoionization lifetimes tau of the Rydberg states are derived from the linewidths by fitting the lines with the Fano formula. Deviations from the scaling law of tau(n*) proportional to, n*3, where n* is the effective quantum number of the Rydberg state, are observed. This observation is ascribed to perturbations by nearby triplet Rydberg states, which shorten the autoionization lifetimes of the singlet Rydberg levels. PMID:18315042
NASA Astrophysics Data System (ADS)
Yang, Xueliang; Zhou, Jingang; Jones, Brant; Ng, C. Y.; Jackson, William M.
2008-02-01
The photoionization efficiency (PIE) spectra of metastable sulfur (S) atoms in the D1 and S1 states have been recorded in the 73350-84950cm-1 frequency range by using a velocity-mapped ion imaging apparatus that uses a tunable vacuum ultraviolet laser as the ionization source. The S(D1) and S(S1) atoms are produced by the 193nm photodissociation of CS2. The observed PIE spectra of S(D1) and S(S1) shows 35 autoionizing resonances with little or no contribution from direct photoionization into the S +(S3/24)+e- ionization continuum. Velocity-mapped ion images of the S+ at the individual autoionizing Rydberg resonances are used to distinguish whether the lower state of the resonance originates from the D1, S1, or P3 states. The analysis and assignment of the Rydberg peaks revealed 22 new Rydberg states that were not previously known. The autoionization lifetimes ? of the Rydberg states are derived from the linewidths by fitting the lines with the Fano formula. Deviations from the scaling law of ?(n *)?n*3, where n* is the effective quantum number of the Rydberg state, are observed. This observation is ascribed to perturbations by nearby triplet Rydberg states, which shorten the autoionization lifetimes of the singlet Rydberg levels.
Yang Xueliang; Zhou Jingang; Jones, Brant; Ng, C. Y.; Jackson, William M. [Department of Chemistry, University of California, Davis, California, 95616 (United States)
2008-02-28
The photoionization efficiency (PIE) spectra of metastable sulfur (S) atoms in the {sup 1}D and {sup 1}S states have been recorded in the 73 350-84 950 cm{sup -1} frequency range by using a velocity-mapped ion imaging apparatus that uses a tunable vacuum ultraviolet laser as the ionization source. The S({sup 1}D) and S({sup 1}S) atoms are produced by the 193 nm photodissociation of CS{sub 2}. The observed PIE spectra of S({sup 1}D) and S({sup 1}S) shows 35 autoionizing resonances with little or no contribution from direct photoionization into the S{sup +}({sup 4}S{sub 3/2})+e{sup -} ionization continuum. Velocity-mapped ion images of the S{sup +} at the individual autoionizing Rydberg resonances are used to distinguish whether the lower state of the resonance originates from the {sup 1}D, {sup 1}S, or {sup 3}P states. The analysis and assignment of the Rydberg peaks revealed 22 new Rydberg states that were not previously known. The autoionization lifetimes {tau} of the Rydberg states are derived from the linewidths by fitting the lines with the Fano formula. Deviations from the scaling law of {tau}(n*){proportional_to}n*{sup 3}, where n* is the effective quantum number of the Rydberg state, are observed. This observation is ascribed to perturbations by nearby triplet Rydberg states, which shorten the autoionization lifetimes of the singlet Rydberg levels.
Experimental and theoretical studies on Rydberg states of CH2CO in the region 120-220 nm
NASA Astrophysics Data System (ADS)
Chiang, Su-Yu; Bahou, Mohammed; Wu, Yu-Jong; Lee, Yuan-Pern
2002-09-01
Absorption spectra of CH2CO and CD2CO in the region 120-220 nm were recorded with a continuously tunable light source of synchrotron radiation. Our spectra show improved sensitivity and resolution with no interference from continuous absorptions reported previously. Transitions to Rydberg states associated with excitation to 3s-9s, 3px-5px, and 3d orbitals are assigned based on observed vibronic patterns, isotopic shifts, effective quantum numbers, and comparison with vertical excitation energies predicted with theoretical calculations using time-dependent density functional theory (TD-DFT). Several transitions are reassigned and new vibrational progressions are identified for some Rydberg states. The major active modes for the ns Rydberg series are the CDouble_BondC stretching (nu4) and the CDouble_BondO stretching (nu2) modes; the CH2 scissor (nu3) mode is also active in several transitions. TD-DFT using a polarized basis set (PBS) proves to be an excellent method for predictions of vertical excitation energies and oscillator strengths, especially for higher Rydberg states.
Vibrational branching ratios following two-color excitation of autoionizing np Rydberg states of H2
NASA Astrophysics Data System (ADS)
O'Halloran, M. A.; Dehmer, P. M.; Tomkins, F. S.; Pratt, S. T.; Dehmer, J. L.
1988-07-01
The vibrational branching ratios of the autoionizing ungerade np(sigma) 1Sigma(+)u and np(pi) 1Pi(u) Rydberg states of H2 are determined experimentally by means of two-color resonantly enhanced multiphoton-ionization photoelectron spectroscopy, using two-step excitation via the (E,F)1Sigma(+)g (v-prime = E2) resonant intermediate state. Sample spectra are shown, and the results are presented in a table. The branching is found to favor the v(+) = 1 channel (94-96 percent) over the v(+) = 0 channel (4-6 percent) in general, although v(+) = 0 branching ratios of up to 18 percent are observed in some cases and attributed to interchannel coupling of low-ionization-efficiency low-n/high-v interlopers.
Superradiance in ultracold Rydberg gases
Tun Wang; S. F. Yelin; R. Cote; E. E. Eyler; S. M. Farooqi; P. L. Gould; M. Kostrun; D. Tong; D. Vrinceanu
2006-08-28
Experiments in dense, ultracold gases of rubidium Rydberg atoms show a considerable decrease of the radiative excited state lifetimes compared to dilute gases. This accelerated decay is explained by collective and cooperative effects, leading to superradiance. A novel formalism to calculate effective decay times in a dense Rydberg gas shows that for these atoms the decay into nearby levels increases by up to three orders of magnitude. Excellent agreement between theory and experiment follows from this treatment of Rydberg decay behavior.
Excited states of the helium-antihydrogen system.
Sharipov, Vasily; Labzowsky, Leonti N; Plunien, Günter
2007-03-01
Potential energy curves for excited leptonic states of the helium-antihydrogen system are calculated within the Ritz variational approach. An explicitly correlated ansatz for the leptonic wave function is employed describing accurately the motion of the leptons (two electrons and positron) in the field of the helium nucleus and of the antiproton with an arbitrary orbital angular momentum projection Lambda onto the internuclear axis. Results for Lambda=0, 1, and 30 are presented. For quasibound states with large values of Lambda and rotational quantum numbers J>Lambda no annihilation and rearrangement decay channels occur; i.e., they are metastable. PMID:17358528
T. Laycock; B. Olmos; I. Lesanovsky
2011-02-10
The creation of collective many-body quantum states from a two-dimensional lattice gas of atoms is studied. Our approach relies on the van-der-Waals interaction that is present between alkali metal atoms when laser excited to high-lying Rydberg s-states. We focus on a regime in which the laser driving is strong compared to the interaction between Rydberg atoms. Here energetically low-lying many-particle states can be calculated approximately from a quadratic Hamiltonian. The potential usefulness of these states as a resource for the creation of deterministic single-photon sources is illustrated. The properties of these photon states are determined from the interplay between the particular geometry of the lattice and the interatomic spacing.
Observation of electric quadrupole transitions to Rydberg nd states of ultracold rubidium atoms
Tong, D.; Farooqi, S. M.; Kempen, E. G. M. van; Pavlovic, Z.; Stanojevic, J.; Cote, R.; Eyler, E. E.; Gould, P. L.
2009-05-15
We report the observation of dipole-forbidden, but quadrupole-allowed, one-photon transitions to high-Rydberg states in Rb. Using pulsed uv excitation of ultracold atoms in a magneto-optical trap, we excite 5s{yields}nd transitions over a range of principal quantum numbers n=27-59. Compared to dipole-allowed (E1) transitions from 5s{yields}np, these E2 transitions are weaker by a factor of approximately 2000. We also report measurements of the anomalous np{sub 3/2}:np{sub 1/2} fine-structure transition strength ratio for n=28-75. Both results are in agreement with theoretical predictions.
Manipulating Rydberg atoms close to surfaces at cryogenic temperatures
NASA Astrophysics Data System (ADS)
Thiele, T.; Filipp, S.; Agner, J. A.; Schmutz, H.; Deiglmayr, J.; Stammeier, M.; Allmendinger, P.; Merkt, F.; Wallraff, A.
2014-07-01
Helium atoms in Rydberg states have been manipulated coherently with microwave radiation pulses near a gold surface and near a superconducting NbTiN surface at a temperature of 3K. The experiments were carried out with a skimmed supersonic beam of metastable (1s)1(2s)11S0 helium atoms excited with laser radiation to np Rydberg levels with principal quantum number n between 30 and 40. The separation between the cold surface and the center of the collimated beam is adjustable down to 250?m. Short-lived np Rydberg states were coherently transferred to the long-lived ns state to avoid radiative decay of the Rydberg atoms between the photoexcitation region and the region above the cold surfaces. Further coherent manipulation of the ns Rydberg states with pulsed microwave radiation above the surfaces enabled measurements of stray electric fields and allowed us to study the decoherence of the atomic ensemble. Adsorption of residual gas onto the surfaces and the resulting slow buildup of stray fields was minimized by controlling the temperature of the surface and monitoring the partial pressures of H2O, N2, O2, and CO2 in the experimental chamber during the cool-down procedure. Compensation of the stray electric fields to levels below 100mV /cm was achieved over a region of 6mm along the beam-propagation direction which, for the 1770-m/s beam velocity, implies the possibility to preserve the coherence of the atomic sample for several microseconds above the cold surfaces.
Simulations of the effect of final state interactions on the scattering reponses of helium droplets
Yang, Jian
1996-01-01
We study the effect of final state interactions (FSI) on the scattering responses of Helium droplets. By computing the s-wave component of the one-body density matrix of a Helium droplet, we find strong similarity between bulk Helium and Helium...
Microwave transitions between pair states composed of two Rb Rydberg atoms
NASA Astrophysics Data System (ADS)
Lee, Jeonghun; Gallagher, Tom
2015-05-01
Microwave transitions between pair states composed of two Rb Rydberg atoms in a magneto-optical trap are investigated. Our current interest is the transition from ndnd to (n+1)d(n-2)f states. This transition is allowed because the dipole-dipole induced configuration interaction between the ndnd state and the energetically close (n+2)p(n-2)f state admixes some of the latter state into the former. The resonance frequencies of the ndnd-(n+1)d(n-2)f transitions for n = 35 to 42 have been measured and found to agree well with the calculated values. In addition, the power shifts of the resonance frequencies have been measured for n = 35 to 42. The dependence of the fractional population transfer from the ndnd to (n+1)d(n-2)f states on the microwave field strength and atomic density has been measured and can be compared to a simple theoretical model. This work has been supported by the Air Force Office of Scientific Research.
NASA Astrophysics Data System (ADS)
Nedeljkovi?, N. N.; Majki?, M. D.; Galija, S. M. D.
2012-11-01
We elaborate the quantum-mechanical analysis using the two-state vector model to investigate the formation of intermediate Rydberg states of multiply charged ions (core charge Z ? 1, principal quantum number nA ? 1) interacting with solid surfaces in the grazing incidence geometry. For the fixed initial and final states of the active electron, the two wavefunctions are used to describe the transitional electron state at the time t. Considering the projectile motion classically, the effect of projectile velocity is taken into account in accordance with Galilean invariance. The population probabilities of the intermediate Rydberg states are obtained in the analytical form, which enables an analysis of the localization and the selectivity of the process, for various ion-surface parameters. Ions ArZ+, KrZ+ and XeZ+ with Z ? [5, 35] interacting with Al-surface are considered as an example. The results are compared with the classical overbarrier predictions and the measured kinetic energy gain due to the image acceleration of the ions. It is demonstrated that the ionic velocity influences the ion-surface distance at which the formation of the particular intermediate Rydberg state is mainly localized, as well as the probability for this formation.
Grein, Friedrich
2011-07-28
MRCI results are reported for the vertical excitation energies (VEE) and oscillator strengths f of doublet states of OClO up to 11 eV, including 3b(1) ? 4s, 4p, 3d, 5s, 5p, 4d, and most 1a(2), 8a(1), 5b(2) ? 4s and 4p Rydberg states. The lowest Rydberg states 3b(1) ? 4s and 3b(1) ? 4p(x) have mixed valence-Rydberg character. The observed spectral bands were reassigned to include valence states which have generally higher oscillator strengths. The well-known valence state 1(2)A(2) has a VEE of 3.63 eV, and a relatively high f of 0.042. Overall, the calculated oscillator strengths are in good agreement with measured values. The lowest quartet state, 1(4)B(2), lies at 6.95 eV. Quartet Rydberg states start with 1a(2) ? 4s at 9.28 eV. According to calculated vertical ionization potentials (VIP) of OClO, the second VIP at 12.59 eV is reassigned from 1(3)B(1) to 1(3)B(2) (ionization from 1a(2), rather than 8a(1)), and the third VIP at 12.63 eV from 1(1)B(1) to 1(3)B(1) (ionization from 8a(1)). Vertical electron detachment energies of OClO(-) have been calculated up to 8.9 eV. There is good agreement with experimental values. PMID:21806116
Few-body bound states of dipole-dipole-interacting Rydberg atoms
NASA Astrophysics Data System (ADS)
Kiffner, Martin; Huo, Mingxia; Li, Wenhui; Jaksch, Dieter
2014-05-01
We show that the resonant dipole-dipole interaction can give rise to bound states between two and three Rydberg atoms with nonoverlapping electron clouds. The dimer and trimer states arise from avoided level crossings between states converging to different fine-structure manifolds in the limit of separated atoms. We analyze the angular dependence of the potential wells, characterize the quantum dynamics in these potentials, and discuss methods for their production and detection. Typical distances between the atoms are of the order of several micrometers which can be resolved in state-of-the-art experiments. The potential depths and typical oscillation frequencies are about one order of magnitude larger as compared to the dimer and trimer states investigated by M. Kiffner et al. [Phys. Rev. A 86, 031401(R) (2012), 10.1103/PhysRevA.86.031401] and M. Kiffner, W. Li, and D. Jaksch [Phys. Rev. Lett. 111, 233003 (2013), 10.1103/PhysRevLett.111.233003], respectively. We find that the dimer and trimer molecules can be aligned with respect to the axis of a weak electric field.
Matthíasson, Kristján; Long, Jingming; Wang, Huasheng; Kvaran, Ágúst
2011-04-28
Mass spectra were recorded for (2 + n) resonance enhanced multiphoton ionization (REMPI) of HCl as a function of resonance excitation energy in the 88865-89285 cm(-1) region to obtain two-dimensional REMPI data. Band spectra due to two-photon resonance transitions to number of Rydberg states (?' = 0, 1, and 2) and the ion-pair state V((1)?(+)(?' = 0)) for H(35)Cl and H(37)Cl were identified, assigned, and analyzed with respect to Rydberg to ion-pair interactions. Perturbations show as line-, hence energy level-, shifts, as well as ion signal intensity variations with rotational quantum numbers, J', which, together, allowed determination of parameters relevant to the nature and strength of the state interactions as well as dissociation and ionization processes. Whereas near-resonance, level-to-level, interactions are found to be dominant in heterogeneous state interactions (?? ? 0) significant off-resonance interactions are observed in homogeneous interactions (?? = 0). The alterations in Cl(+) and HCl(+) signal intensities prove to be very useful for spectra assignments. Data relevant to excitations to the j(3)?(0(+)) Rydberg states and comparison with (3 + n) REMPI spectra allowed reassignment of corresponding spectra peaks. A band previously assigned to an ? = 0 Rydberg state was reassigned to an ? = 2 state (?(0) = 88957.6 cm(-1)). PMID:21528955
Properties of Th3+ from Optical Spectroscopy of High-L Rydberg states of Th2+
NASA Astrophysics Data System (ADS)
Keele, Julie; Woods, Shannon; Lundeen, Stephen; Fehrenbach, Charles
2011-05-01
The Fr-like Thorium ion, Th3+, has one valence electron outside a Rn-like closed shell, but its ground electronic state is 2F5/2 instead of 2S1/2 due to the high nuclear charge. The positions of the lowest seven levels of this ion have been established by optical spectroscopy, but no other properties have been measured previously. We measure the properties of the Th3+ ground state that control its long-range interactions, such as polarizabilities and permanent moments, by attaching a single electron in a non-penetrating Rydberg state and measuring the details of its binding energy using the Resonant Excitation Stark Ionization Spectroscopy (RESIS) technique. A typical transition is n = 29 to n ' = 72. The laser excitation partially resolves the complex fine structure pattern in the lower state caused by the long-range interactions, and this leads to measurements of the core ion properties controlling those interactions. Supported by the Chemical Sciences, Geosciences, and Biosciences Division of the Office of Basic Energy Science, U.S. Dept. of Energy.
Ground State Hyperfine Structure of Muonic Helium Atom
A. A. Krutov; A. P. Martynenko
2008-07-21
On the basis of the perturbation theory in the fine structure constant $\\alpha$ and the ratio of the electron to muon masses we calculate one-loop vacuum polarization and electron vertex corrections and the nuclear structure corrections to the hyperfine splitting of the ground state of muonic helium atom $(\\mu e ^4_2He)$. We obtain total result for the ground state hyperfine splitting $\\Delta \
V. I. Yarygin; V. N. Sidelnikov; I. I. Kasikov; V. S. Mironov; S. M. Tulin
2003-01-01
The results of experimental study of a condensate of cesium excited states (Rydberg matter) are presented. The possibility\\u000a of condensate formation was predicted theoretically first by Prof. .A. Manykin and coauthors from the Russian Research Center\\u000a Kurchatov Institute and experimentally observed by L. Holmlid and coauthors from the Chalmers University, Sweden. In a thermionic\\u000a energy converter with interelectrode medium, where,
Rydberg atom spectroscopy enabled by blackbody radiation ionization
Lu Xiaoxu; Sun Yuan; Metcalf, Harold [Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794-3800 (United States)
2011-09-15
We have excited helium atoms from their metastable 2 {sup 3} S state to Rydberg states in the range 13
Method for laser spectroscopy of metastable pionic helium atoms
NASA Astrophysics Data System (ADS)
Hori, M.; Sótér, A.; Aghai-Khozani, H.; Barna, D.; Dax, A.; Hayano, R. S.; Murakami, Y.; Yamada, H.
2015-04-01
The PiHe collaboration is currently attempting to carry out laser spectroscopy of metastable pionic helium atoms using the high-intensity ? - beam of the ring cyclotron facility of the Paul Scherrer Institute. These atoms are heretofore hypothetical three-body Coulomb systems each composed of a helium nucleus, a ? - occupying a Rydberg state, and an electron occupying the 1s ground state. We briefly review the proposed method by which we intend to detect the laser spectroscopic signal. This complements our experiments on metastable antiprotonic helium atoms at CERN.
Method for laser spectroscopy of metastable pionic helium atoms
NASA Astrophysics Data System (ADS)
Hori, M.; Sótér, A.; Aghai-Khozani, H.; Barna, D.; Dax, A.; Hayano, R. S.; Murakami, Y.; Yamada, H.
2015-08-01
The PiHe collaboration is currently attempting to carry out laser spectroscopy of metastable pionic helium atoms using the high-intensity ? - beam of the ring cyclotron facility of the Paul Scherrer Institute. These atoms are heretofore hypothetical three-body Coulomb systems each composed of a helium nucleus, a ? - occupying a Rydberg state, and an electron occupying the 1s ground state. We briefly review the proposed method by which we intend to detect the laser spectroscopic signal. This complements our experiments on metastable antiprotonic helium atoms at CERN.
Far infrared stimulated emission from the ns and nf Rydberg states of NO
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.
Bound states of interacting helium atoms
Stefan V. Mashkevich; Stanislav I. Vilchynskyy
1999-11-11
We study the possibility of existence of bound states for two interacting He-4 atoms. It is shown that for some potentials, there exist not only discrete levels but also bands akin to those in the Kronig--Penney model.
Analysis of the 8f, 9f, and 10f, v=1 Rydberg states of N2
NASA Astrophysics Data System (ADS)
McCormack, E. F.; Pratt, S. T.; Dehmer, J. L.; Dehmer, P. M.
1991-09-01
The autoionizing (X 2?+g) 8f, 9f, and 10f, v=1 states of N2 have been studied by using double-resonance ionization spectroscopy via numerous rotational levels of the a 1?g, v'=5 state. These nf states lie in a complex region of the spectrum that also contains transitions to high vibrational levels of the b' 1?+u valence state and Rydberg states that converge to the X 2?+g, A 2?u, and B 2?+u states of the ion. A long-range interaction model, which is based on the interaction of the Rydberg electron with the polarizability and quadrupole moment of the N+2 ion core, has been used to intepret the f-state structure and to identify the extent of perturbations due to interactions with nearby states. A generalized least-squares fit of the model to the energies of the unperturbed 8f state yields an effective quadrupole moment of (3.2+/-0.1)ea20 and an isotropic polarizability of (16.1+/-0.4)a30 for the 2?+g, v+=1 state of the ion. In addition, a new state that is observed to perturb the 9f, v=1 state is tentatively identified as the previously unobserved ( 2?u)3d? 1?u, v=2 state. The results presented here complete the interpretation of the single-photon absorption spectrum of N2 from the first ionization potential at ~125 667 to ~126 850 cm-1.
Classical limit states of the helium atom J. A. West,1,2
Stroud, Carlos R.
Classical limit states of the helium atom J. A. West,1,2 Z. D. Gaeta,1,3 and C. R. Stroud, Jr.1,2 1 for the simplest such atom, helium, this extension is nontrivial because the old quantum theory of Bohr was never wave packets are used to explore the classical limit states of helium. A class of shape
LBNL-42730 1 Collisional Perturbation of States in Atomic Ytterbium by Helium and Neon
Pines, Alexander
LBNL-42730 1 Collisional Perturbation of States in Atomic Ytterbium by Helium and Neon D in atomic ytterbium by helium and neon buffer gases are reported. We find upper limits for the quenching with respect to helium (He) and neon (Ne) are measured. The 3 P0 state is populated by exciting Yb atoms from
Bound states of helium atom in dense plasmas
Sabyasachi Kar; Y. K. Ho
2006-01-01
We have obtained the bound 1s2 1S, 1s2s 1,3S, and 1s2p 1,3P states energies of helium atom in dense plasma environments in accurate variation calculations. A screened Coulomb potential to represent the Debye model is used for the interaction between the charged particles. A correlated wave function consisting of a generalized exponential expansion has been used to take care of
Bound D-states of helium atom under Debye screening
Sabyasachi Kar; Y. K. Ho
2007-01-01
We have investigated the 1snd1,3D (3 ? n ? 7) state energies of helium atom embedded in weakly coupled plasma environments using the Rayleigh-Ritz variational method. The effect of the plasma environment is taken care of using a Debye screening model. A correlated wave function involving exponential expansion has been used to represent correlation between the charge particles. The bound
Rates of blackbody radiation-induced transitions from Rydberg states of alkali atoms
NASA Astrophysics Data System (ADS)
Ovsiannikov, V. D.; Glukhov, I. L.; Nekipelov, E. A.
2011-10-01
General properties are considered of three different terms in the imaginary part of the Stark effect on nS, nP and nD Rydberg states of alkali atoms in the field of environmental blackbody radiation with temperature in the ranges between T = 100 K and T = 3000 K. The terms are equal to the rates of decay Pdnl(T), excitation Penl(T) and ionization Pionnl(T) and may be separated and determined independently of each other. Corresponding numerical data calculated together with the rates of spontaneous decay Pspnl in the region of principal quantum numbers n from n = 10-1000 are transformed into fractional rates Rd(e, ion)nl(T) = Pd(e, ion)nl(T)/Pnlsp. The asymptotic dependences on T and n display an essential difference between the fractional rates of ionization Rionnl(T)~Tn2/3 and the rates of decay (excitation) Rd(e)nl(T)~Tn, approximated by two different asymptotic formulae, one for Rionnl(T) and another one for Rd(e)nl(T). The approximation polynomials with coefficients, determined from the curve-fitting polynomial interpolation procedure for three values of n between n = 15 and n = 150 at three values of temperature T = 100, 300, 1000 K, reproduce the calculated values with fractional departures below 2-3% in the regions from n = 10 to n = 1000 at temperatures from T = 100 K to T = 3000 K.
Electromagnetically induced transparency in a Y system with single Rydberg state
NASA Astrophysics Data System (ADS)
Tian, Xue-Dong; Liu, Yi-Mou; Yan, Xiao-Bo; Cui, Cui-Li; Zhang, Yan
2015-06-01
We study the transmitted intensity and correlation properties of a probe field propagating through a sample of cold interacting 87Rb atoms driven into the Y level configuration with single Rydberg state. We find two electromagnetically induced transparency (EIT) windows in the transmission spectrum. One window is linear since it is immune to the incident probe field. The other window depth is sensitive to the incident probe intensity, exhibiting cooperative nonlinearity. Meanwhile, the linear window is low but the transmissivity at the nonlinear window can reach nearly 100% in case of the weak probe intensity. When two EIT windows overlap, the cooperative optical nonlinearity plays a leading role in the degenerate window. In addition, the probe propagation is affected by its two-photon correlation which is suppressed at the center of nonlinear window and is enhanced near the boundaries of two windows. The two-photon correlation is also sensitive to the probe field, and that means we can attain the strongest photon bunching (anti-bunching) effect by controlling the probe and coupling fields.
Structure of the Xe 6s and 6s' Rydberg states in supercritical Ar
NASA Astrophysics Data System (ADS)
Li, Luxi; Shi, Xianbo; Evans, C. M.; Findley, G. L.
2008-05-01
In this paper, we present new absorption measurements and complete lineshape simulations (including all blue satellite bands) of the Xe 6s and 6s' Rydberg states doped into Ar from low density to the density of the triple point liquid, at both noncritical temperatures and on an isotherm near (+0.5^oC) the critical temperature of Ar. Using these simulations, as well as the known Ar induced shift of the ionization energy of a dopantootnotetextC. M. Evans and G. L. Findley, Phys. Rev. A 72, 022717 (2005)., the Ar induced shift in the Xe 6s and 6s' term energies is determined and is shown to exhibit a large critical point effect. The nature of this critical point effect is discussed. The experimental measurements reported here were performed at the University of Wisconsin Synchrotron Radiation Center (NSF DMR-0537588). This work was supported by grants from the Petroleum Research Fund, from the Professional Staff Congress--City University of New York, and from the Louisiana Board of Regents Support Fund.
A New Wide Range Equation of State for Helium-4
Ortiz Vega, Diego O
2013-08-01
-fuel constituents is relatively high to justify their extraction, requiring an original concentration of helium greater than 0.3 % ? During the production of liquefied natural gas (LNG), most likely liquid methane. Helium is extracted from the tail gases... for helium decreased after the war, and by the 1990s private demand for helium far exceeded federal demand. The 1996 Helium Privatization Act redefined the government?s role in helium production. The Bureau of Land Management was made responsible...
Hyperfine structure of excited state of muonic helium atom
A. A. Krutov; A. P. Martynenko
2012-08-23
The recoil, vacuum polarization and electron vertex corrections of first and second orders in the fine structure constant $\\alpha$ and the ratio of electron to muon and electron to \\alpha-particle masses are calculated in the hyperfine splitting of the $1s^{(e)}_{1/2}2s^{(\\mu)}_{1/2}$ state of muonic helium atom (\\mu e ^4_2He) on the basis of a perturbation theory. We obtain total result for the muonically excited state hyperfine splitting $\\Delta \
Zeller, Wolfgang; Bonato, Thorsten; Reinelt, Gerhard; Schmelcher, Peter
2012-01-01
We investigate static properties of laser-driven, ultracold Rydberg atoms confined to one- and two-dimensional uniform lattices in the limit of vanishing laser coupling. The spectral structure of square lattices is compared to those of linear chains and similarities as well as differences are pointed out. Furthermore, we employ a method based on elements of graph theory to numerically determine the laser detuning-dependent ground states of various lattice geometries. Ground states for chains as well as square and rectangular lattices are provided and discussed.
Wolfgang Zeller; Michael Mayle; Thorsten Bonato; Gerhard Reinelt; Peter Schmelcher
2012-06-01
We investigate static properties of laser-driven, ultracold Rydberg atoms confined to one- and two-dimensional uniform lattices in the limit of vanishing laser coupling. The spectral structure of square lattices is compared to those of linear chains and similarities as well as differences are pointed out. Furthermore, we employ a method based on elements of graph theory to numerically determine the laser detuning-dependent ground states of various lattice geometries. Ground states for chains as well as square and rectangular lattices are provided and discussed.
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 ? 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 > + ? | R > with ? << 1 . Using spin language to describe this two level system, our proposed Ramsey scheme rotates the spins by angle ?, 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 ? can be used to experimentally measure the strength and power law dependence of the dressed Rydberg atom interaction.
Magnetic trapping of long-lived cold Rydberg atoms.
Choi, J-H; Guest, J R; Povilus, A P; Hansis, E; Raithel, G
2005-12-01
We report on the trapping of long-lived strongly magnetized Rydberg atoms. 85Rb atoms are laser cooled and collected in a superconducting magnetic trap with a strong bias field (2.9 T) and laser excited to Rydberg states. Collisions scatter a small fraction of the Rydberg atoms into long-lived high-angular momentum "guiding-center" Rydberg states, which are magnetically trapped. The Rydberg atomic cloud is examined using a time-delayed, position-sensitive probe. We observe magnetic trapping of these Rydberg atoms for times up to 200 ms. Oscillations of the Rydberg-atom cloud in the trap reveal an average magnetic moment of the trapped Rydberg atoms of approximately -8microB. These results provide guidance for other Rydberg-atom trapping schemes and illuminate a possible route for trapping antihydrogen. PMID:16384371
Magnetic Trapping of Long-Lived Cold Rydberg Atoms
Choi, J.-H.; Guest, J.R.; Povilus, A.P.; Hansis, E.; Raithel, G. [FOCUS Center, Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1040 (United States)
2005-12-09
We report on the trapping of long-lived strongly magnetized Rydberg atoms. {sup 85}Rb atoms are laser cooled and collected in a superconducting magnetic trap with a strong bias field (2.9 T) and laser excited to Rydberg states. Collisions scatter a small fraction of the Rydberg atoms into long-lived high-angular momentum 'guiding-center' Rydberg states, which are magnetically trapped. The Rydberg atomic cloud is examined using a time-delayed, position-sensitive probe. We observe magnetic trapping of these Rydberg atoms for times up to 200 ms. Oscillations of the Rydberg-atom cloud in the trap reveal an average magnetic moment of the trapped Rydberg atoms of {approx_equal}-8{mu}{sub B}. These results provide guidance for other Rydberg-atom trapping schemes and illuminate a possible route for trapping antihydrogen.
NASA Astrophysics Data System (ADS)
Long, Jingming; Wang, Huasheng; Kvaran, Ágúst
2013-01-01
(2 + n) resonance enhanced multiphoton ionization mass spectra for resonance excitations to diabatic E1?+ (v') Rydberg and V 1?+ (v') ion-pair states (adiabatic B1?+(v') states) of HiCl (i = 35,37) and HiBr (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 E1?+ (v')(v' = 1) for H35Cl and v' = 0 for H79Br 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.
Dynamics of Low-Density Ultracold Rydberg Gases
J. O. Day; E. Brekke; T. G. Walker
2008-03-07
Population dynamics in weakly-excited clouds of ultracold $^{87}$Rb Rydberg atoms were studied by means of trap loss, fluorescence detection, and state dependent stimulated emission. Rydberg atoms were excited to various nl Rydberg states via continuous two-photon excitation from a magneto-optical trap. A stimulated emission probe laser was then used to bring the Rydberg atoms down to the 6P$_{3/2}$ state, allowing state-dependent detection of the Rydberg atoms. Measurements of trap loss and fluorescent emission reveal information about the evolution of the Rydberg populations. In particular, population in the initial Rydberg state quickly transfers to other Rydberg states by a non-collisional mechanism, likely superradiant emission. The trap-loss measurements are consistent with black-body ionization as the dominant loss mechanism.
Kalemos, Apostolos; Prosmiti, Rita
2014-09-14
We present for the first time a coherent ab initio study of 39 states of valence, Rydberg, and ion-pair character of the diatomic interhalogen ICl species through large scale multireference variational methods including spin-orbit effects coupled with quantitative basis sets. Various avoided crossings are responsible for a non-adiabatic behaviour creating a wonderful vista for its theoretical description. Our molecular constants are compared with all available experimental data with the aim to assist experimentalists especially in the high energy regime of up to ?95?000 cm{sup ?1}.
NASA Astrophysics Data System (ADS)
Kato, M.; Morishita, Y.; Oura, M.; Yamaoka, H.; Tamenori, Y.; Okada, K.; Matsudo, T.; Gejo, T.; Suzuki, I. H.; Saito, N.
2007-01-01
The high-resolution absolute photoabsorption cross section with an absolute photon energy scale for Ne in the energy region of 864-872 eV (1s-1np Rydberg states) has been measured using a multi-electrode ionization chamber and monochromatized synchrotron radiation. The natural lifetime width of Ne 1s-13p resonance state has been obtained to be 252 ą 5 meV. The Ne+ (1s-1) ionization potential is determined to be 870.16 ą 0.04 eV by using the Rydberg formula. These absolute values are supposed to be more reliable than those previously reported.
Kato, M.; Morishita, Y.; Suzuki, I. H.; Saito, N.; Oura, M.; Yamaoka, H.; Okada, K.; Matsudo, T.; Gejo, T.
2007-01-19
The high-resolution absolute photoabsorption cross section with an absolute photon energy scale for Ne in the energy region of 864-872 eV (1s-1np Rydberg states) has been measured using a multi-electrode ionization chamber and monochromatized synchrotron radiation. The natural lifetime width of Ne 1s-13p resonance state has been obtained to be 252 {+-} 5 meV. The Ne+ (1s-1) ionization potential is determined to be 870.16 {+-} 0.04 eV by using the Rydberg formula. These absolute values are supposed to be more reliable than those previously reported.
Rabani, Eran
in a diffusive like fashion of many smaller steps, except for a fraction of trajectories where prompt ionization of Rydberg states that can be detected by delayed pulsed ionization spectroscopy which is n 90 for both states by ionization, is also examined. The observed decay kinetics are as previously reported for cold
Density effects on high-n molecular Rydberg states: CH3I in He, Ne, Ar, and Kr
NASA Astrophysics Data System (ADS)
Köhler, A. M.; Reininger, R.; Saile, V.; Findley, G. L.
1987-01-01
Absorption studies of the high-n Rydberg states of CH3I perturbed by varying number densities of He, Ne, Ar, and Kr (up to 23.0, 24.0, 11.3, and 6.6×1020 cm-3, respectively) are reported. Energy shifts, which increase with increasing perturber number density, are observed and analyzed for both discrete [nd(2E3/2)] and autoionizing [nd'(2E1/2)] states. These shifts vary linearly with the perturber number density for principal quantum numbers n>=10. Moreover, depending upon the nature of the perturber, these shifts are to the blue region (He), slightly to the blue region (or nearly zero) (Ne), or the red region (Ar and Kr). We explain these results quantitatively on the basis of the electron scattering length in the various rare gases, as well as on the polarization of the medium by CH3I+. For low perturber number densities, it is well known that the Fermi model of perturber effects on high-n Rydberg states is invalid. The present experimental results show, for the first time, that this model also fails at high number densities. On the other hand, the energy shifts can be reproduced quantitatively by extending a model developed by Alekseev and Sobel'man to high number densities.
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 1?u (v?=0-14), c3 1?u (v?=0-3), o3 1?u (v?=0-3), b? 1?u+ (v?=0-10), c?4 1?u+ (v?=0-3), G 3?u (v?=0-3), and F 3?u (v?=0-3). We further adjusted the cross sections of the RV states by extending the vibronic contributions to unmeasured v?-levels via the relative excitation probabilities (REPs) as discussed in [6]. This resulted in REP-scaled ICSs over the following vibrational levels for the singlet ungerade states: b(0-19), c3(0-4), o3(0-4), b?(0-16), and c?4(0-8). Comparison of the ICSs of [6] with available EEL based measurements, theoretical calculations, and emission based work generally shows good agreement within error estimations, except with the recent reevaluation provided by [1]. Further, we have extended these results, using the recent EEL data of [3], to include the unfolding of better resolved features above ~13.82eV. This effort is to provide improved cross sections for these RV states, in particular for the b? 1?u+ and c?4 1?u+ states, with inclusion of more upper vibrational levels. Future optical emission work should include re-measurements of excitation shape functions of the singlet ungerade states utilizing better spectral resolution than past determinations (e.g., [2,4]) to avoid uncertainties associated with unresolved and/or blended spectral features as well as J-dependent predissociation. Further development of theoretical treatments of N2 excitation is also in need. We will also present analysis of our new low-energy, near-threshold excitation cross sections for the valence states of N2, including a 1?g (v?) levels. Acknowledgement: This work was performed at CSUF and JPL, Caltech, under contract with NASA. We gratefully acknowledge financial support through NASA's OPR and PATM programs and NSF-PHY-RUI-0096808 & -0965793 and NSF-AGS-0938223. References: [1] Ajello, J. M., M. H. Stevens, I. Stewart, et al. (2007), GRL, 34, L24204 [2] Ajello, J. M., G. K. James, and B. O. Franklin (1989), PRA, 40, 3524-56 [3] Heays, A. N., B. R. Lewis, S. T. Gibson, et al. (2012), PRA, 85, 012705 [4] James, G. K., J. M. Ajello, B. Franklin, and D. E. Shemansky (1990), JPB, 23, 2055-81 [5] Khakoo, M. A., C. P. Malone, P. V. Johnson, et al. (2008), PRA, 77, 012704 [6] Malone, C. P., P. V. Johnson, X. Liu, et al. (2012), PRA, 85, 062704
Continetti, Robert E.
Three-Body Dissociation Dynamics of the Low-Lying Rydberg States of H3 and D3 Christopher M (Received 19 April 2004; published 8 October 2004) The dynamics of the three-body dissociative charge information on the nonadiabatic couplings that govern the three-body dissociation of the lowest-lying Rydberg
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.
Quantum mechanical calculation of Rydberg-Rydberg Auger decay rates
Kiffner, Martin; Li, Wenhui; Jaksch, Dieter
2015-01-01
We present quantum mechanical calculations of the Auger decay rate $\\Gamma_A$ of two Rubidium Rydberg atoms with weakly overlapping electron clouds. The two-electron wavefunction is modelled by a single Slater determinant of $nd$ Rydberg orbitals with principal quantum number $n\\le35$. The dependence of $\\Gamma_A$ on the atom-atom separation $R$ is well described by a power law $\\Gamma_A \\propto R^{\\alpha}$ and we calculate the exponents $\\alpha$ for various initial states. For atomic separations equal to the size of the Rydberg electron wave function $R_n$ we find that $\\Gamma_A \\propto n^{-5}$. We discuss the importance of Auger decay compared to other contributions to the electron dynamics in the two Rydberg atom system.
Quantum mechanical calculation of Rydberg-Rydberg Auger decay rates
Martin Kiffner; Davide Ceresoli; Wenhui Li; Dieter Jaksch
2015-07-13
We present quantum mechanical calculations of the Auger decay rate $\\Gamma_A$ of two Rubidium Rydberg atoms with weakly overlapping electron clouds. The two-electron wavefunction is modelled by a single Slater determinant of $nd$ Rydberg orbitals with principal quantum number $n\\le35$. The dependence of $\\Gamma_A$ on the atom-atom separation $R$ is well described by a power law $\\Gamma_A \\propto R^{\\alpha}$ and we calculate the exponents $\\alpha$ for various initial states. For atomic separations equal to the size of the Rydberg electron wave function $R_n$ we find that $\\Gamma_A \\propto n^{-5}$. We discuss the importance of Auger decay compared to other contributions to the electron dynamics in the two Rydberg atom system.
NASA Astrophysics Data System (ADS)
Schütte, Bernd; Arbeiter, Mathias; Fennel, Thomas; Jabbari, Ghazal; Gokhberg, Kirill; Kuleff, Alexander I.; Vrakking, Marc J. J.; Rouzée, Arnaud
2015-05-01
Interatomic Coulombic decay (ICD) describes a process, where an excited atom relaxes by transferring its energy to an atom in the environment that gets ionized. So far, ICD has been observed following XUV ionization or excitation of clusters. Here we present novel results of an intracluster Coulombic decay mechanism induced by intense NIR pulses and following Rydberg atom formation in the generated nanoplasma. When a highly-excited Rydberg atom relaxes to its ground state by transferring its excess energy to a weakly bound electron in the environment, electrons with kinetic energies close to the atomic ionization potential are emitted. We show evidence for such an intracluster Coulombic decay process that leaves clear signatures in the electron kinetic energy spectra. ICD is time-resolved in a pump-probe experiment, where a weak probe pulse depopulates the excited states, leading to a quenching of the ICD signal. We find a decay time of 87 ps, which is siginificantly longer than for previous ICD observations, where inner-shell holes were created by XUV pulses. Intracluster Coulombic decay is found to be a generic process that takes places in atomic and molecular clusters and at different wavelengths. It may play an important role in biological systems and in astronomical plasmas. Previous affiliation: Max-Born-Institut, Berlin, Germany.
Laser sources for efficient two-step Positronium excitation to Rydberg states
NASA Astrophysics Data System (ADS)
Becucci, M.; Ferrari, G.; Boscolo, I.; Castelli, F.; Cialdi, S.; Villa, F.; Giammarchi, M. G.
2011-05-01
Antihydrogen production by charge exchange reaction between Positronium atoms and antiprotons benefits from an efficient excitation of Positronium atoms to high- n levels (Rydberg levels). A two-step optical excitation, the first from ground to n = 3 and the second from this level to a Rydberg level, is proposed and a proper laser system to be developed is discussed. The requirements on the energy and bandwidth of the excitation laser suggest the use of optical parametric generation technology for both wavelengths. The laser system is composed of two subsystems: one for the generation of 205 nm radiation and the other for the generation of 1670 nm radiation. We report on the progress towards the realization of the short wavelength source.
Rydberg states of the ArCO2 and KrCO2 van der Waals molecules
NASA Astrophysics Data System (ADS)
Dehmer, P. M.
1985-07-01
Relative photoionization cross sections were determined for ArCO2 at a wavelength resolution of 0.24 Ĺ in the regions of both the Ar*+CO2 and the Ar+CO*2 dissociation limits (690-920 Ĺ) and for KrCO2 at a wavelength resolution of 0.4 Ĺ in the region of the Kr+CO*2 dissociation limits (690-780 Ĺ). The dimer ionization potentials are 13.59ą0.04 eV (912.5ą2.5 Ĺ) for ArCO2 and 13.33ą0.04 eV (930.0ą3.0 Ĺ) for KrCO2. Combining these values with the known value of the CO2 ionization potential and the known (or estimated) values of the ArCO2 and KrCO2 dissociation energies yields values for the dimer ion ground state dissociation energies of 0.20ą0.04 eV for ArCO+2 and 0.47ą0.05 eV for KrCO+2. Rydberg structure is observed in the photoionization cross section of ArCO2 corresponding to dissociation limits of the type Ar*(nd,ns)+CO2; however, discrete structure is observed only near the Ar*(3d,5s)+CO2 dissociation limits. van der Waals structure corresponding to the higher Ar*+CO2 limits is diffuse and red degraded. Molecular Rydberg structure also is observed in the photoionization cross sections of both ArCO2 and KrCO2 corresponding to dissociation limits of the type Ar+CO*2. Prominent van der Waals structure is observed corresponding to dissociation limits based on members of the CO2 Henning sharp and diffuse Rydberg series, which converge to CO+2B 2?+u; however, no van der Waals structure is observed corresponding to dissociation limits based on members of the CO2 Tanaka-Ogawa Rydberg series, which converge to CO+2A 2?u. Various experimental evidence indicates that neither vibrational predissociation of the excited van der Waals dimer nor vibrational predissociation of the dimer ion can account completely for the absence of van der Waals structure corresponding to the Tanaka-Ogawa series in CO2.
Yu, Shengrui; Su, Shu; Dai, Dongxu; Yuan, Kaijun; Yang, Xueming
2015-04-21
The state-to-state dynamics of high-n Rydberg H-atom scattering with para-H2 at the collision energies of 0.45 and 1.07 eV have been studied using the H-atom Rydberg tagging time-of-flight technique. Both the inelastic scattering and reactive scattering are observed in the experimental time-of-flight spectra. The products H2(v', j' = odd) come only from reactive scattering and present clearly forward-backward asymmetric angular distributions, which differ from those of the corresponding ion-molecule reaction. The products H2(v', j' = even), however, come from both reactive scattering and inelastic scattering. Simulating the rotational distribution from reactive scattering, we found that most of the H2(v', j' = even) products come from inelastic scattering. The angular distributions of the product H2(v', j' = even) are consistent with what is predicted by the conventional textbook mechanism of inelastic scattering, and are a little different from those of the corresponding ion-molecule inelastic scattering. These results suggest that the effect of Rydberg electron could not be neglected in describing the differential cross sections of H* + para-H2 scattering. From the simulation, the branching ratios of the inelastic scattering channel were determined to be 66% and 79% at the collision energies of 0.45 and 1.07 eV, respectively. PMID:25162182
Diagrams of the state of a steady-state arc discharge in hydrogen and helium
NASA Astrophysics Data System (ADS)
Vasil'ev, E. N.
2014-12-01
The temperature, electric field strength, and specific and integrated powers of energy mechanisms of an axisymmetric steady-state equilibrium arc discharge in hydrogen and helium under atmospheric pressure are calculated for various values of the current and radius. The results of calculations are presented in the form of state diagrams intended for estimating the main energy characteristics of electric arcs.
NASA Astrophysics Data System (ADS)
Liu, Fusheng; Tian, Chunling; Cai, Lingcang; Jing, Fuqian
Based on ab initio self-consistent-field technique and atomic cluster method, the various many-body interactions among atoms in dense helium have been computed. By this way, the static high pressure measurements are perfectly explained. A new simple formula for calculation the total energy is proposed by directly combining the two-body potential with the atomic potential. Over a large volume and temperature range of 7.5~1.74 cm3/mol and 2000~21000K, the equation of state (EOS) of helium is given.
Probing RF electric fields with Rydberg atoms
NASA Astrophysics Data System (ADS)
Schwettmann, Arne; Sedlacek, Jonathon; Gentry, Cale; Shaffer, James
2011-05-01
Using an atom chip setup, we investigate the use of high-lying Rb Rydberg atoms (n > 30) as sensitive electric field sensors. Rydberg atoms are sensitive to electric fields due to their large polarizability and the large transition dipole moments between nearby Rydberg states. We excite ultracold Rydberg atoms in a magnetic wire-trap. The magnetic trap is loaded from a mirror magneto-optical trap. We then probe the interaction of Rydberg atoms with small RF electric fields using an EIT scheme. The presence of very small external RF fields modifies the EIT line shape significantly, because the RF field couples strongly to the transitions between Rydberg levels. In future experiments, it will be possible to miniaturize this setup for use as a sensor, by using room temperature atoms in microcells. We acknowledge funding from ARO (W911NF-08-0257).
interacting Rydberg polaritons P. Bienias,1, S. Choi,2, O. Firstenberg,2 M. F. Maghrebi,3 M. Gullans,3 M. D-light polaritons interacting via atomic Ryd- berg states. We use a diagrammatic method to analytically derive the scattering properties of two polaritons. We identify new parameter regimes where polariton-polariton
Classical limit states of the helium atom J. A. West,1,2
Stroud Jr., Carlos R.
Classical limit states of the helium atom J. A. West,1,2 Z. D. Gaeta,1,3 and C. R. Stroud, Jr.1,2 1 wave packets are used to explore the classical limit states of helium. A class of shape-preserving orbits is studied under the classical adiabatic approximation that separates the dynamics of the two
Semiclassical quantization of Bohr orbits in the helium atom
NASA Astrophysics Data System (ADS)
Belov, V. V.; Maksimov, V. A.
2007-05-01
We use the complex WKB-Maslov method to construct the semiclassical spectral series corresponding to the resonance Bohr orbits in the helium atom. The semiclassical energy levels represented as the Rydberg tetra series correspond to the doubly symmetrically excited states of helium-like atoms. This level series contains the Rydberg triple series reported by Richter and Wintgen in 1991, which corresponds to the Z2+e-e- configuration of electrons observed by Eichmann and his collaborators in experiments on the laser excitation of the barium atom in 1992. The lower-level extrapolation of the formula obtained for the semiclassical spectrum gives the value of the ground state energy, which differs by 6% from the experimental value obtained by Bergeson and his collaborators in 1998. We also calculate the fine structure of the semiclassical spectrum due to the spin-orbit and spin-spin interactions of electrons.
Wireless network control of interacting Rydberg atoms.
Sanders, Jaron; van Bijnen, Rick; Vredenbregt, Edgar; Kokkelmans, Servaas
2014-04-25
We identify a relation between the dynamics of ultracold Rydberg gases in which atoms experience a strong dipole blockade and spontaneous emission, and a stochastic process that models certain wireless random-access networks. We then transfer insights and techniques initially developed for these wireless networks to the realm of Rydberg gases, and explain how the Rydberg gas can be driven into crystal formations using our understanding of wireless networks. Finally, we propose a method to determine Rabi frequencies (laser intensities) such that particles in the Rydberg gas are excited with specified target excitation probabilities, providing control over mixed-state populations. PMID:24815645
Wireless network control of interacting Rydberg atoms
Jaron Sanders; Rick van Bijnen; Edgar Vredenbregt; Servaas Kokkelmans
2014-04-30
We identify a relation between the dynamics of ultracold Rydberg gases in which atoms experience a strong dipole blockade and spontaneous emission, and a stochastic process that models certain wireless random-access networks. We then transfer insights and techniques initially developed for these wireless networks to the realm of Rydberg gases, and explain how the Rydberg gas can be driven into crystal formations using our understanding of wireless networks. Finally, we propose a method to determine Rabi frequencies (laser intensities) such that particles in the Rydberg gas are excited with specified target excitation probabilities, providing control over mixed-state populations.
Helium P-State Energies and Quantum Defect Analysis
NASA Astrophysics Data System (ADS)
Valdez, Travis; Peck, Ryan; Drake, Gordon W. F.
2015-05-01
Quantum defects provide a simple and accurate method of extending known atomic energies for low principal quantum number n to higher n up to the series limit, and including the scattering phase shift beyond. We will present new calculations of improved accuracy for the 1 snp1 P and 3 P states of helium up to n = 12 , based on variational calculations in Hylleraas coordinates. The results will be used to determine accurate values for the coefficients in the quantum defect expansion, ? =?0 +?2 /n*2 +?4 /n*4 + ... , where n* = n - ? . We will also test the usual assumption that only the even powers of 1 /n* need be included. In addition, we will study the effectiveness of a unitary transformation in reducing the numerical linear dependence of the basis set for large basis sets. Research supported by the Natural Sciences and Engineering Research Council of Canada.
Yang, Xinzheng; Boggs, James E
2006-05-21
The electronic states of the BBr molecule, including 12 valence states and 12 low-lying Rydberg states, have been studied at the theoretical level of MR-CISD+Q with all-electron aug-cc-pVQZ basis sets and Douglas-Kroll [Ann. Phys. (N.Y.) 82, 89 (1974)] scalar relativistic correction. The spin-orbit coupling effect in the valence states was calculated by the state interaction approach with the full Breit-Pauli Hamiltonian. This is the first multireference ab initio study of the excited electronic states of BBr. Potential energy curves of all states were plotted with the help of the avoided crossing rule between electronic states of the same symmetry. The structural properties of these states were analyzed. Computational results reproduced most experimental data well. The transition properties of the a (3)Pi(0(+) ), a (3)Pi(1), and A (1)Pi(1) states to the ground state X (1)Sigma(0(+) ) (+) transitions were obtained, including the transition dipole moments, the Franck-Condon factors, and the radiative lifetimes. The evaluated radiative lifetime of the a (3)Pi(0(+) ), and a (3)Pi(1) states are near 1 ms, much longer than that of the A (1)Pi(1) state. PMID:16729814
NASA Astrophysics Data System (ADS)
Dewangan, D. P.
2008-01-01
We give an exact quantum formula for the z-component of the dipole matrix element between parabolic states of a hydrogen atom in terms of the Jacobi polynomials. The formula extends the range of numerical computation to larger values of the parabolic quantum numbers for which computation from the standard textbook formula, which is in terms of the hypergeometric functions, is defined. We obtain an accurate quantum expression of the z-dipole matrix element in terms of the ordinary Bessel functions for transition between nearby Rydberg parabolic states. We derive for the first time the formula of the z-dipole matrix element of the correspondence principle method directly from the quantum expression, and in the process of derivation, clarify the nature of classical-quantum correspondence. The expressions obtained in this work solve the problem of computation of the z-dipole matrix element of hydrogen to a large extent.
Polarization control of absorption of virtual dressed states in helium
NASA Astrophysics Data System (ADS)
Reduzzi, Maurizio; Hummert, Johan; Dubrouil, Antoine; Calegari, Francesca; Nisoli, Mauro; Frassetto, Fabio; Poletto, Luca; Chen, Shaohao; Wu, Mengxi; Gaarde, Mette B.; Schafer, Kenneth; Sansone, Giuseppe
2015-09-01
The extreme ultraviolet absorption spectrum of an atom is strongly modified in the presence of a synchronized intense infrared field. In this work we demonstrate control of the absorption properties of helium atoms dressed by an infrared pulse by changing the relative polarization of the infrared and extreme ultraviolet fields. Light-induced features associated with the dressed 1 s 2 s , 1 s 3 s , and 1 s 3 d states, referred to as 2 s+ , 3 są , and 3 dą light-induced states, are shown to be strongly modified or even eliminated when the relative polarization is rotated. The experimental results agree well with calculations based on the solution of the time-dependent Schrödinger equation using a restricted excitation model that allows efficient treatment of the three-dimensional problem. We also present an analysis of the light-induced states based on Floquet theory, which allows for a simple explanation of their properties. Our results open a new route to creating controllable superpositions of dipole allowed and nondipole allowed states in atoms and molecules.
NASA Astrophysics Data System (ADS)
Camargo, Francisco; Ding, Roger; Aman, James; Zhang, Xinyue; Whalen, Joseph; Fields, Robert; Dunning, F. Barry; Killian, Thomas
2014-05-01
We discuss the design and construction of a new apparatus for creating and studying long-range interactions in ultracold gases of strontium by exploiting Rydberg states, either through their direct excitation or through laser-induced Rydberg dressing. Strontium features one fermionic (87Sr) and three bosonic (84Sr, 86Sr, 88Sr) isotopes, all of which have been brought to quantum degeneracy. It also possesses singlet and triplet Rydberg states that furnish a wide variety of attractive and repulsive interactions. Furthermore, strontium Rydberg atoms feature an optically active core electron which can be used to manipulate and detect Rydberg atoms. These features make strontium a promising system for studying interactions in ultracold Rydberg gases. Research supported by Rice University, the NSF, the AFOSR, Shell, and the Robert A. Welch Foundation.
NASA Astrophysics Data System (ADS)
Oks, E.
2004-02-01
We derived analytical expressions for the energy of classical Circular Rydberg States (CRS) in collinear electric ( F) and magnetic ( B) fields of arbitrary strengths. Previously published explicit expressions for the energy E were given only for the region of a weak electric field F and only in the limits of B to 0 and B to infty . We offered formulas for the dependence of the classical ionization threshold F c ( B) and of the energy at this threshold E c ( B) valid for the magnetic field B of an arbitrary strength. We also analyzed the stability of the motion by going beyond the CRS. In addition, for two important particular cases previously studied in the literature - classical CRS in a magnetic field only and classical CRS in an electric field only - we presented some new results as well.
Higher-order contributions to fine structure in high-L Rydberg states of Si{sup 2+}
Snow, E. L.; Lundeen, S. R. [Department of Physics, SUNY Fredonia, Fredonia, New York 14063 (United States); Department of Physics, Colorado State University, Fort Collins, Colorado 80523 (United States)
2007-06-15
Measured fine-structure patterns of high-L Rydberg states have often been used to extract measurements of both the dipole and the quadrupole polarizability of their positive ion cores. Dipole polarizabilities deduced in this way are apparently quite accurate, judging by comparison with calculated values, but the accuracy of quadrupole polarizabilities is questionable. The polarizabilities of Na-like silicon are a good example. Recent fine-structure measurements seem to imply a quadrupole polarizability, in clear disagreement with calculations. This apparent discrepancy is due to misinterpretation of the experimental data, neglecting the effects of higher-order terms in the polarization potential that significantly alter the slope of the traditional polarization plots. When these terms are calculated, and their magnitude estimated, the discrepancy is eliminated. The implications of the higher-order terms for analysis of high-L fine-structure patterns are discussed.
NASA Astrophysics Data System (ADS)
Falsaperla, P.; Fonte, G.
1994-10-01
A variational method, based on some results due to T. Kato [Proc. Phys. Soc. Jpn. 4, 334 (1949)], and previously discussed is here applied to the hydrogen atom in uniform magnetic fields of tesla in order to calculate, with a rigorous error estimate, energy eigenvalues, energy eigenfunctions, and oscillator strengths relative to Rydberg states up to just below the field-free ionization threshold. Making use of a basis (parabolic Sturmian basis) with a size varying from 990 up to 5050, we obtain, over the energy range of -190 to -24 cm-1, all of the eigenvalues and a good part of the oscillator strengths with a remarkable accuracy. This, however, decreases with increasing excitation energy and, thus, above ~-24 cm-1, we obtain results of good accuracy only for eigenvalues ranging up to ~-12 cm-1.
Falsaperla, P.; Fonte, G. (Dipartimento di Fisica,Universita di Catania, Corso Italia 57, I-95129 Catania (Italy) Istituto Nazionale di Fisica Nucleare, Sezione di Catania, Corso Italia 57, I-95129 Catania (Italy))
1994-10-01
A variational method, based on some results due to T. Kato [Proc. Phys. Soc. Jpn. 4, 334 (1949)], and previously discussed is here applied to the hydrogen atom in uniform magnetic fields of tesla in order to calculate, with a rigorous error estimate, energy eigenvalues, energy eigenfunctions, and oscillator strengths relative to Rydberg states up to just below the field-free ionization threshold. Making use of a basis (parabolic Sturmian basis) with a size varying from 990 up to 5050, we obtain, over the energy range of [minus]190 to [minus]24 cm[sup [minus]1], all of the eigenvalues and a good part of the oscillator strengths with a remarkable accuracy. This, however, decreases with increasing excitation energy and, thus, above [similar to][minus]24 cm[sup [minus]1], we obtain results of good accuracy only for eigenvalues ranging up to [similar to][minus]12 cm[sup [minus]1].
Entanglement entropies in the ground states of helium-like atoms
Przemyslaw Koscik; Anna Okopinska
2014-06-01
We examine the entanglement in the ground states of helium and helium-like ions using an original Hylleraas expansion. The von Neumann and linear entropies of the reduced density matrix are accurately computed by performing the Schmidt decomposition of the S singlet spatial wavefunctions. The results presented are more accurate than currently available in published literature.
Quantum Field Theory and the Helium Atom: 101 Years Later
J. Sucher
1996-12-11
Helium was first isolated on Earth in 1895, by Sir William Ramsey. One hundred and one years later, it seems like a good time to review our current theoretical understanding of the helium atom. Helium has played an important role in the development of both quantum mechanics and of quantum field theory. The early history of helium is sketched. Various aspects of the modern theory are described in some detail, including (1) the computation of fine structure to order \\alpha^2 Ry and \\alpha^3 Ry, (2) the decay of metastable states, and (3) Rydberg states and long-range forces. A brief survey is made of some of the recent work on the quantum field theory of He and He-like ions.
Multichannel long-range Rydberg molecules
Eiles, Matthew T
2015-01-01
A generalized class of ultra-long-range Rydberg molecules is proposed 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 multi-scale binding possibilities that could present novel options for quantum manipulation.
Large Energy Superpositions via Rydberg Dressing
Mohammadsadegh Khazali; Hon Wai Lau; Adam Humeniuk; Christoph Simon
2015-09-03
We propose to create superposition states of over 100 Strontium atoms being in a ground state or metastable 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 of order 250 eV in energy, allowing highly sensitive tests of energy decoherence models. We take into account the effects of higher-order nonlinearities, spatial inhomogeneity of the interaction, decay from the Rydberg state, and diminishing Rydberg level separation for increasing principal number.
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.
Wójcik, Antoni
in the weak-field limit. Both the total ioniza- tion rate 5 and the photoelectron angular distribution PAD 6 at the peak intensity , and TK is the initial-state Kepler period TK 2 n0 3 a.u., with n0 being the initial of the PAD caused by a migration of population among degenerate Rydberg states, originating in direct n 0, l
Long, Jingming; Wang, Huasheng; Kvaran, Ágúst
2013-01-28
(2 + n) resonance enhanced multiphoton ionization mass spectra for resonance excitations to diabatic E(1)?(+) (v') Rydberg and V (1)?(+) (v') ion-pair states (adiabatic B(1)?(+)(v') states) of H(i)Cl (i = 35,37) and H(i)Br (i = 79,81) were recorded as a function of excitation wavenumber (two-dimensional REMPI). Simulation analyses of ion signal intensities, deperturbation analysis of line shifts and interpretations of line-widths are used to derive qualitative and quantitative information concerning the energetics of the states, off-resonance interactions between the E states and V states, closest in energy as well as on predissociation channels. Spectroscopic parameters for the E(1)?(+) (v')(v' = 1) for H(35)Cl and v' = 0 for H(79)Br states, interaction strengths for E - V state interactions and parameters relevant to dissociation of the E states are derived. An overall interaction and dynamical scheme, to describe the observations for HBr, is proposed. PMID:23387585
Sharkey, Keeper L.; Bubin, Sergiy; Adamowicz, Ludwik
2011-01-15
Very accurate variational nonrelativistic calculations are performed for the five lowest Rydberg {sup 2}D states (1s{sup 2}nd{sup 1}, n=3,...,7) of the lithium atom ({sup 7}Li). The finite-nuclear-mass approach is employed and the wave functions of the states are expanded in terms of all-electron explicitly correlated Gaussian function. Four thousand Gaussians are used for each state. The calculated relative energies of the states determined with respect to the {sup 2}S 1s{sup 2}2s{sup 1} ground state are systematically lower than the experimental values by about 2.5 cm{sup -1}. As this value is about the same as the difference between the experimental relative energy between {sup 7}Li{sup +} and {sup 7}Li in their ground-state energy and the corresponding calculated nonrelativistic relative energy, we attribute it to the relativistic effects not included in the present calculations.
Laser power dependence of the Beutler-Fano profiles for the autoionizing Rydberg states of Ba
NASA Astrophysics Data System (ADS)
Afrousheh, Kourosh
2014-11-01
The change of the Beutler-Fano profiles of the asymmetric autoionizing lines of barium as a function of the excitation laser power was investigated. Utilizing two-photon absorption, the J = 0 and 2 levels of a few members of the 5d3/2 nd3/2 autoionizing Rydberg series above the first ionization limit of barium were excited in a heat-pipe oven. As the laser power was changed, the transitions with relatively symmetric lineshapes showed the expected power broadening. However, the transitions with asymmetric lineshapes experienced a dramatic profile change while displaying a less significant power broadening. The remarkable profile changes are attributed to the interference between different ionization channels even at the highest excitation laser power.
Two-Electron Excitation of an Interacting Cold Rydberg Gas
Millen, J.; Lochead, G.; Jones, M. P. A.
2010-11-19
We report the creation of an interacting cold Rydberg gas of strontium atoms. We show that the excitation spectrum of the inner valence electron is sensitive to the interactions in the Rydberg gas, even though they are mediated by the outer Rydberg electron. By studying the evolution of this spectrum we observe density-dependent population transfer to a state of higher angular momentum l. We determine the fraction of Rydberg atoms transferred, and identify the dominant transfer mechanism to be l-changing electron-Rydberg collisions associated with the formation of a cold plasma.
Cold and Ultracold Rydberg Atoms in Strong Magnetic Fields
Pohl, T; Schmelcher, P
2009-01-01
Cold Rydberg atoms exposed to strong magnetic fields possess unique properties which open the pathway for an intriguing many-body dynamics taking place in Rydberg gases consisting of either matter or anti-matter systems. We review both the foundations and recent developments of the field in the cold and ultracold regime where trapping and cooling of Rydberg atoms have become possible. Exotic states of moving Rydberg atoms such as giant dipole states are discussed in detail, including their formation mechanisms in a strongly magnetized cold plasma. Inhomogeneous field configurations influence the electronic structure of Rydberg atoms, and we describe the utility of corresponding effects for achieving tightly trapped ultracold Rydberg atoms. We review recent work on large, extended cold Rydberg gases in magnetic fields and their formation in strongly magnetized ultracold plasmas through collisional recombination. Implications of these results for current antihydrogen production experiments are pointed out, and ...
Gilchrist, A. J.; Ritchie, G. A. D. [Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ (United Kingdom)
2013-06-07
(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.
NASA Astrophysics Data System (ADS)
Tu, Yanfei; Kim, May E.; Shahriar, Selim M.
2014-10-01
Previously, we had proposed the technique of light shift imbalance induced blockade which leads to a condition where a collection of non-interacting atoms under laser excitation remains combined to a superposition of the ground and the fist excited states, thus realizing a collective state quantum bit which in turn can be used to realize a quantum computer. In this paper, we show first that the light shift imbalance by itself is actually not enough to produce such a blockade, and explain the reason by the limitation of our previous analysis had reached this constraint. We then show that by introducing Rydberg interaction, it is possible to achieve such a blockade for a wide range of parameters. Analytic arguments used to establish these results are confirmed by numerical simulations. The fidelity of coupled quantum gates based on such collective state qubits is highly insensitive to the exact number of atoms in the ensemble. As such, this approach may prove be viable for scalable quantum computing based on neutral atoms.
Lowest state n=1 of H atom Rydberg matter: many eV energy release in Coulomb explosions
Shahriar Badiei; Leif Holmlid
2004-01-01
Neutral Rydberg species with well defined kinetic energy of 9.4 eV per unit mass are emitted from a cloud of Rydberg matter (RM) when a 5 ns laser pulse passes through it. The energy of 9.4 eV agrees with the energy relased at a principal quantum number n = 1 in RM. This level is expected in the RM form only for hydrogen
Phase Modulation in Rydberg Dressed Multi-Wave Mixing processes.
Zhang, Zhaoyang; Zheng, Huaibin; Yao, Xin; Tian, Yaling; Che, Junling; Wang, Xiuxiu; Zhu, Dayu; Zhang, Yanpeng; Xiao, Min
2015-01-01
We study the enhancement and suppression of different multi-waving mixing (MWM) processes in a Rydberg-EIT rubidium vapor system both theoretically and experimentally. The nonlinear dispersion property of hot rubidium atoms is modulated by the Rydberg-Rydberg interaction, which can result in a nonlinear phase shift of the relative phase between dark and bright states. Such Rydberg-induced nonlinear phase shift can be quantitatively estimated by the lineshape asymmetry in the enhancedand suppressed MWM processes, which can also demonstrate the cooperative atom-light interaction caused by Rydberg blockaded regime. Current study on phase shift is applicable to phase-sensitive detection and the study of strong Rydberg-Rydberg interaction. PMID:26053438
NASA Astrophysics Data System (ADS)
Liverts, Evgeny Z.; Barnea, Nir
2012-03-01
A simple Mathematica (version 7) code for computing S-state energies and wave functions of two-electron (helium-like) ions is presented. The elegant technique derived from the classical papers of Pekeris is applied. The basis functions are composed of the Laguerre functions. The method is based on the perimetric coordinates and specific properties of the Laguerre polynomials. Direct solution of the generalized eigenvalues and eigenvectors problem is used, distinct from the Pekeris works. No special subroutines were used, only built-in objects supported by Mathematica. The accuracy of the results and computation times depend on the basis size. The ground state and the lowest triplet state energies can be computed with a precision of 12 and 14 significant figures, respectively. The accuracy of the higher excited states calculations is slightly worse. The resultant wave functions have a simple analytical form, that enables calculation of expectation values for arbitrary physical operators without any difficulties. Only three natural parameters are required in the input. The new version of Mathematica code takes into account the fact that the negative hydrogen ion has only one bound state. New version program summaryProgram title: TwoElAtomSL(SH) Catalogue identifier: AEHY_v2_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEHY_v2_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 27 998 No. of bytes in distributed program, including test data, etc.: 286 543 Distribution format: tar.gz Programming language: Mathematica 7.0 and 8.0 Computer: Any PC with a Mathematica installation Operating system: Any which supports Mathematica; tested under Microsoft Windows XP and Linux SUSE 11.0 RAM:?10 bytes Classification: 2.1, 2.2, 2.7, 2.9 Catalogue identifier of previous version: AEHY_v1_0 Journal reference of previous version: Comput. Phys. Comm. 182 (2011) 1790 Does the new version supersede the previous version?: Yes Nature of problem: The Schrödinger equation for atoms (ions) with more than one electron has not been solved analytically. Approximate methods must be applied in order to obtain the wave functions or other physical attributes from quantum mechanical calculations. Solution method: The S-wave function is expanded into a triple set of basis functions which are composed of the exponentials combined with the Laguerre polynomials in the perimetric coordinates. Using specific properties of the Laguerre polynomials, solution of the two-electron Schrödinger equation reduces to solving the generalized eigenvalues and eigenvector problem for the proper Hamiltonian. The unknown exponential parameter is determined by means of minimization of the corresponding eigenvalue (energy). Reasons for new version: The need to take into account the fact that the negative hydrogen ion ( Z=1) has only one bound (ground) state. Summary of revisions: Minor amendments were made in Cell 2 and Cell 5 of both TwoElAtomSH and TwoElAtomSL programs. Restrictions: Firstly, the too large length of expansion (basis size) takes too much computation time and operative memory giving no perceptible improvement in accuracy. Secondly, the number of shells ? in the wave function expansion enables one to calculate the excited nS-states up to n=?+1 inclusive. Running time: 2-60 minutes (depends on basis size and computer speed).
Calculation of Helium Ground State Energy by Bohr's Theory-Based Methods
Tsubono, Youhei
2009-01-01
Bohr's model agreed with the hydrogen spectrum results, but did not agree with the spectrum of Helium. Here we show that Bohr's model-based methods can calculate the experimental value (-79.005 eV) of Helium ground state energy correctly. we suppose the orbital planes of the two electrons are perpendicular to each other. By a computational method, we calculate the Coulomb force among the particles, and the number of de Broglie's waves contained in the short segment at short time intervals. Our results demonstrate that two electrons of Helium are actually moving around, not as electron clouds.
NASA Astrophysics Data System (ADS)
Zhou, Yan; Grimes, David; Colombo, Tony; Klein, Ethan; Barnum, Timothy J.; Field, Robert W.
2014-06-01
Rydberg-Rydberg electronic transitions provide information about the electronic structure of the ion-core and each of the fundamental mechanisms by which a light electron exchanges energy and angular momentum with heavy nuclei. Normally, Rydberg electronic states have been indirectly observed via a sequence of laser-excitation steps, for which detection of transitions is accomplished by either fluorescence- or ionization-based schemes. Electronic transitions of |? n*|<1 between Rydberg states (n* is the effective principal quantum number) have kilo-Debye electric dipole transition moments when n*>30. Such enormous transition moments render Rydberg-Rydberg electronic transitions directly observable. A chirped millimeter wave pulse can simultaneously polarize a 23 GHz chunk of two-level systems. In our spectra of Ca atoms (104 Rydberg atoms/cm3 in a volume of 100 cm3), the resultant Free Induction Decay (FID) from each of these two level systems is down-converted and heterodyne detected at <500 kHz resolution (at 3:1 S:N in a single chirp). Willis Flygare and Brooks Pate are to be thanked! But there is more, especially for molecules! Recently, the Doyle and DeMille research groups have developed a cryogenic buffer gas cooled ablation source, our version of which produces beams of alkaline earth monohalide molecules that are >100x brighter and 10x slower than those produced by our Smalley type supersonic jet ablation source. Our 20 K Neon buffer gas cooled ablation source, in combination with redesign of the resonance region (300 cm3, mm-wave radiation on-axis with the molecular beam) of our CPmmW spectrometer, has resulted in a 1000x increase in brightness of a BaF molecular beam (108 Rydberg molecules/cm3 in a single quantum state) and a 10x improvement in resolution (50 kHz @ 100 GHz). When buffer gas cooled ablation sources are combined with direct detection of FID, a new domain of high resolution molecular spectroscopy begs for exploration!
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 Schrödinger equation for atoms (ions) with more than one electron has not been solved analytically. Approximate methods must be applied in order to obtain the wave functions or another physical attributes from quantum mechanical calculations. Solution method: The S-wave function is expanded into a triple set of basis functions which are composed of the exponentials combined with the Laguerre polynomials in the perimetric coordinates. Using specific properties of the Laguerre polynomials, solution of the two-electron Schrödinger equation reduces to solving the generalized eigenvalues and eigenvector problem for the proper Hamiltonian. The unknown exponential parameter is determined by means of minimization of the corresponding eigenvalue (energy). Restrictions: First, the too large length of expansion (basis size) takes the too large computation time and operative memory giving no perceptible improvement in accuracy. Second, the number of shells ? in the wave function expansion enables one to calculate the excited nS-states up to n=?+1 inclusive. Running time: 2-60 minutes (depends on basis size and computer speed).
First Observation of the Ground-State Hyperfine-Structure Resonance of the Muonic Helium Atom
H. Orth; K.-P. Arnold; P. O. Egan; M. Gladisch; W. Jacobs; J. Vetter; W. Wahl; M. Wigand; V. W. Hughes; G. Zu Putlitz
1980-01-01
The first measurement of the hfs interval Deltanu for the muonic helium atom (4He++mu-e-)0 is reported. In terms of its electronic structure, it is a heavy isotope of hydrogen. Polarized atoms are formed by stopping polarized negative muons in a helium-gas target at 19.4 atm with a 1.5% admixture of Xe. The ground-state hfs splitting Deltanu was measured through observation
NASA Astrophysics Data System (ADS)
Wang, Kwanghsi; McKoy, V.
1991-12-01
Results of studies of rotational ion distributions in the X 2?3/2 and X 2?1/2 spin-orbit states of HCl+ resulting from (2+1') resonance enhanced multiphoton ionization (REMPI) via the S(0) branch of the F 1?2 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 2?3/2 ion and J+=1/2 of the X 2?1/2 ion. Both transitions require an angular momentum change of ?N=-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 1?2 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 1?2 state are also shown.
Ionization of Rydberg atoms by blackbody radiation
NASA Astrophysics Data System (ADS)
Beterov, I. I.; Tretyakov, D. B.; Ryabtsev, I. I.; Entin, V. M.; Ekers, A.; Bezuglov, N. N.
2009-01-01
We have studied ionization of alkali-metal Rydberg atoms by blackbody radiation (BBR). The results of theoretical calculations of ionization rates of Li, Na, K, Rb and Cs Rydberg atoms are presented. The calculations have been performed for nS, nP and nD states for principal quantum numbers n=8-65 at ambient temperatures of 77, 300 and 600 K. The calculations take into account the contributions of BBR-induced redistribution of population between Rydberg states prior to photoionization and field ionization by extraction electric field pulses. The obtained results show that these phenomena affect both the magnitude of the measured ionization rates and their n dependence. A Cooper minimum for BBR-induced transitions between bound Rydberg states of Li has been found. The calculated ionization rates are compared with our earlier measurements of BBR-induced ionization rates of Na nS and nD Rydberg states with n=8-20 at 300 K. Good agreement for all states except nS with n>15 is observed. Useful analytical formulae for quick estimates of BBR ionization rates of Rydberg atoms are presented. Application of BBR-induced ionization signal to measurements of collisional ionization rates is demonstrated.
Reimers, Jeffrey R; McKemmish, Laura K; McKenzie, Ross H; Hush, Noel S
2015-09-23
Ammonia adopts sp(3) hybridization (HNH bond angle 108°) whereas the other members of the XH3 series PH3, AsH3, SbH3, and BiH3 instead prefer octahedral bond angles of 90-93°. We use a recently developed general diabatic description for closed-shell chemical reactions, expanded to include Rydberg states, to understand the geometry, spectroscopy and inversion reaction profile of these molecules, fitting its parameters to results from Equation of Motion Coupled-Cluster Singles and Doubles (EOM-CCSD) calculations using large basis sets. Bands observed in the one-photon absorption spectrum of NH3 at 18.3 eV, 30 eV, and 33 eV are reassigned from Rydberg (formally forbidden) double excitations to valence single-excitation resonances. Critical to the analysis is the inclusion of all three electronic states in which two electrons are placed in the lone-pair orbital n and/or the symmetric valence ?* antibonding orbital. An illustrative effective two-state diabatic model is also developed containing just three parameters: the resonance energy driving the high-symmetry planar structure, the reorganization energy opposing it, and HXH bond angle in the absence of resonance. The diabatic orbitals are identified as sp hybrids on X; for the radical cations XH3(+) for which only 2 electronic states and one conical intersection are involved, the principle of orbital following dictates that the bond angle in the absence of resonance is acos(-1/5) = 101.5°. The multiple states and associated multiple conical intersection seams controlling the ground-state structure of XH3 renormalize this to acos[3?sin(2)(2(1/2)atan(1/2))/2 - 1/2] = 86.7°. Depending on the ratio of the resonance energy to the reorganization energy, equilibrium angles can vary from these limiting values up to 120°, and the anomalously large bond angle in NH3 arises because the resonance energy is unexpectedly large. This occurs as the ordering of the lowest Rydberg orbital and the ?* orbital swap, allowing Rydbergization to compresses ?* to significantly increase the resonance energy. Failure of both the traditional and revised versions of the valence-shell electron-pair repulsion (VSEPR) theory to explain the ground-state structures in simple terms is attributed to exclusion of this key physical interaction. PMID:26190514
Scanning electron microscopy of Rydberg-excited Bose-Einstein condensates
Manthey, T; Niederpruem, T; Langer, P; Guarrera, V; Barontini, G; Ott, H
2014-01-01
We report on the realization of high resolution electron microscopy of Rydberg-excited ultracold atomic samples. The implementation of an ultraviolet laser system allows us to excite the atom, with a single-photon transition, to Rydberg states. By using the electron microscopy technique during the Rydberg excitation of the atoms, we observe a giant enhancement in the production of ions. This is due to $l$-changing collisions, which broaden the Rydberg level and therefore increase the excitation rate of Rydberg atoms. Our results pave the way for the high resolution spatial detection of Rydberg atoms in an atomic sample.
Bound-state QED calculations for antiprotonic helium
NASA Astrophysics Data System (ADS)
Korobov, Vladimir I.; Hilico, Laurent; Karr, Jean-Philippe
2015-04-01
We present new theoretical results for the transition energies of the hydrogen isotope molecular ions and antiprotonic helium atoms. Our consideration includes corrections at the m? 7 order in the nonrecoil limit such as the one-loop self-energy, one-loop vacuum polarization, Wichman-Kroll, and complete two-loop contributions. That allowed to get transition energies for the fundamental transition (v = 0,L = 0)? (1,0) in the hydrogen molecular ion with the relative theoretical uncertainty of 7?10-12 that corresponds to a fractional precision of 1.5?10-11 in determination of the electron-to-proton mass ratio, m p /m e . Correspondingly, for the two-photon transitions in the antiprotonic helium we have 4.7?10-11 as a relative uncertainty for the (33,32)? (31,30) transition frequency and a fractional precision of 3.6?10-11 for an inferred antiproton-to-electron mass ratio.
Strong-Field Excitation of Helium: Bound State Distribution and Spin Effects
NASA Astrophysics Data System (ADS)
Zimmermann, H.; Buller, J.; Eilzer, S.; Eichmann, U.
2015-03-01
Using field ionization combined with the direct detection of excited neutral atoms we measured the distribution of principal quantum number n of excited He Rydberg states after strong-field excitation at laser intensities well in the tunneling regime. Our results confirm theoretical predictions from semiclassical and quantum mechanical calculations and simultaneously underpin the validity of the semiclassical frustrated tunneling ionization model. Moreover, since our experimental detection scheme is spin sensitive in the case of He atoms, we show that strong-field excitation leads to strong population of triplet states. The origin of it lies in the fact that high angular momentum states are accessible in strong-field excitation. Thus, singlet-triplet transitions become possible due to the increased importance of spin-orbit interaction rather than due to direct laser induced spin-flip processes.
Hybridization of Rydberg Electron Orbitals by Molecule Formation
NASA Astrophysics Data System (ADS)
Gaj, A.; Krupp, A. T.; Ilzhöfer, P.; Löw, R.; Hofferberth, S.; Pfau, T.
2015-07-01
The formation of ultralong-range Rydberg molecules is a result of the attractive interaction between a Rydberg electron and a polarizable ground-state atom in an ultracold gas. In the nondegenerate case, the backaction of the polarizable atom on the electronic orbital is minimal. Here we demonstrate how controlled degeneracy of the respective electronic orbitals maximizes this backaction and leads to stronger binding energies and lower symmetry of the bound dimers. Consequently, the Rydberg orbitals hybridize due to the molecular bond.
Hybridization of Rydberg electron orbitals by molecule formation
Gaj, A; Ilzhöfer, P; Löw, R; Hofferberth, S; Pfau, T
2015-01-01
The formation of ultralong-range Rydberg molecules is a result of the attractive interaction between Rydberg electron and polarizable ground state atom in an ultracold gas. In the nondegenerate case the backaction of the polarizable atom on the electronic orbital is minimal. Here we demonstrate, how controlled degeneracy of the respective electronic orbitals maximizes this backaction and leads to stronger binding energies and lower symmetry of the bound dimers. Consequently, the Rydberg orbitals hybridize due to the molecular bond.
Rydberg Atoms Ionisation by Microwave Field and Electromagnetic Pulses
B. Kaulakys; G. Vilutis
1995-04-10
A simple theory of the Rydberg atoms ionisation by electromagnetic pulses and microwave field is presented. The analysis is based on the scale transformation which reduces the number of parameters and reveals the functional dependencies of the processes. It is shown that the observed ionisation of Rydberg atoms by subpicosecond electromagnetic pulses scale classically. The threshold electric field required to ionise a Rydberg state may be simply evaluated in the photonic basis approach for the quantum dynamics or from the multiphoton ionisation theory.
Exotic Self-trapped States of an Electron in Superfluid Helium
NASA Astrophysics Data System (ADS)
Elser, Veit
2015-09-01
We explore the possibility that the fast and exotic negative ions in superfluid helium are electrons bound to quantized vortex structures, the simplest being a ring. In the states we consider, the electron energy is only slightly below the conduction band minimum of bulk helium. To support our proposal, we present two calculations. In the first, we show that the electron pressure on the vortex core is insufficient to cavitate the helium and form an electron bubble. In the second, we estimate the equilibrium radius of the vortex ring that would bind an electron and find it is much smaller than the electron bubble, about 7 Ĺ. The many exotic ions reported in experiments might be bound states of an electron with more complex vortex structures.
Friedland, Lazar
in a certain type of charged particle accelerator 11 , so the term Rydberg accelerator was suggested of the driving frequency at resonance. The adiabatic synchronization allows one to accelerate the electron , measuring the probability of ionization of beams of highly excited hydrogen atoms passing through a micro
EDITORIAL: Special issue on Rydberg physics
NASA Astrophysics Data System (ADS)
Côté, Robin; Pattard, Thomas; Weidemüller, Matthias
2005-01-01
Atoms and molecules in highly excited electronic states ('Rydberg atoms') have been the object of broad scientific research for almost a century. Despite this long history, the field of research has never lost its buoyancy, and recent years in particular have seen a tremendous revival of interest in the physics of Rydberg atoms and molecules from many different perspectives. Rydberg systems touch a wide range of research areas including, among others, ultralong-range molecules, artificial ('designer') atoms, quantum chaos, quantum information, ultracold Rydberg gases and plasmas, and anti-hydrogen formation. Due to the many fields involved, the physical insight and technical know-how are scattered over different communities. The goal of this special issue is to provide an integral overview of the latest developments in this highly innovative research field and to make the physical knowledge available to a wide audience. Groups from various fields of atomic, molecular and optical physics as well as condensed matter and plasma physics have contributed to this issue, which therefore spans a wide range of areas connected through the common theme: 'Rydberg physics'. This name was given to a four-week International Workshop and Seminar which was held from 19 April to 14 May 2004 at the Max-Planck-Institut für Physik Komplexer Systeme in Dresden, Germany, and organized by the three of us. The workshop and seminar programme was a very successful mixture of topics bringing together colleagues working in different but related areas of research centred about the physics of highly excited Rydberg atoms and molecules. We would like to take this opportunity to express our gratitude to the organization team of the MPI-PKS Dresden, especially the Director, Jan-Michael Rost, and the Visitors' Programme coordinator, Mandy Lochar. The generous support of the Max Planck Society, which made this successful workshop and seminar possible, is also gratefully acknowledged. Inspired by the great response to the 'Rydberg physics' conference we thought that it would be timely and appropriate to recognize the importance of Rydberg physics with a special issue of a scientific journal. The 'unbureaucratic' and highly efficient editorial and publishing team of Journal of Physics B: Atomic, Molecular and Optical Physics (J. Phys. B) allowed this to become a reality; it was a real pleasure for us to serve as guest editors. Unlike a conventional conference proceedings, this special issue has not been restricted to participants of the 'Rydberg physics' conference, and all the original papers contained in it have been peer-reviewed to the usual high standards of J. Phys. B. The variety and integrated discussion on the physics of Rydberg systems during the 'Rydberg physics' conference is reflected in the papers presented here. We have tried to group the papers according to the subject areas which are addressed. The first part of this special issue is devoted to high-resolution spectroscopy revealing deeper insights into the structure of Rydberg atoms and molecules as well as electronic interaction processes. The second part contains experimental and theoretical investigations on the influence of external static and oscillatory fields on Rydberg atoms. The third part takes account of the newly established field of ultracold Rydberg gases and plasmas with special emphasis on the appearance of ultralong-range interactions in these systems. Finally, the issue is concluded by articles on new developments including 'exotic' Rydberg systems. We would like to thank all of the participants of the 'Rydberg physics' workshop and seminar, and, in particular, the contributors to this special collection of papers, for their involvement. We are deeply indebted to the J. Phys. B editorial and publishing team both for making its realization possible in an extremely efficient way, and for the journal's commitment to the physics of Rydberg systems. We are impressed by the continuing progress in this fascinating and rapidly growing field of research and we look forward to many
Redistributing populations of Rydberg atoms with half-cycle pulses
Hu, S.X.; Collins, L.A. [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
2004-04-01
Expanding the wave function in terms of eigenstates, we calculated the population redistribution of high-Rydberg hydrogen atoms under the interactions of external time-dependent electromagnetic fields. Our numerical results show that populations of Rydberg atoms can be driven down to lower n levels with a train of half-cycle pulses. Oscillations of the Rydberg population through both n levels and l levels are observed during these interactions. The approach may have applications in providing an effective mechanism for producing near ground-state atoms from the initially high-Rydberg distributions found in recombining ultracold plasmas such as encountered in the antihydrogen trapping experiments at CERN.
One-Dimensional Rydberg Gas in a Magnetoelectric Trap
Mayle, Michael; Hezel, Bernd; Lesanovsky, Igor; Schmelcher, Peter
2007-09-14
We study the quantum properties of Rydberg atoms in a magnetic Ioffe-Pritchard trap which is superimposed by a homogeneous electric field. Trapped Rydberg atoms can be created in long-lived electronic states exhibiting a permanent electric dipole moment of several hundred Debye. The resulting dipole-dipole interaction in conjunction with the radial confinement is demonstrated to give rise to an effectively one-dimensional ultracold Rydberg gas with a macroscopic interparticle distance. We derive analytical expressions for the electric dipole moment and the required linear density of Rydberg atoms.
Electric-Field Induced Dipole Blockade with Rydberg Atoms
Vogt, Thibault; Viteau, Matthieu; Chotia, Amodsen; Zhao Jianming; Comparat, Daniel; Pillet, Pierre [Laboratoire Aime Cotton, CNRS, Universite Paris-Sud, Batiment 505, Campus d'Orsay, 91405 Orsay (France)
2007-08-17
High resolution laser Stark excitation of np (60
A nonlinear programming approach to lower bounds for the ground-state energy of helium
Porras, I.; Feldmann, D.M.; King, F.W.
1999-02-20
Lower-bound estimates for the ground-state energy of the helium atom are determined using nonlinear programming techniques. Optimized lower bounds are determined for single-particle, radially correlated, and general correlated wave functions. The local nature of the method employed makes it a very severe test of the accuracy of the wave function.
Ground-State Entanglement Properties of Helium Atom in a Finite Spherical Cavity
NASA Astrophysics Data System (ADS)
Ko?cik, Przemys?aw; Saha, Jayanta K.
2015-05-01
The effects of the spatial confinement on the ground-state entanglement properties of the helium atom have been studied. The finite oscillator potential is used to represent the confining potential. The transition to the free atom regime and the harmonic confinement regime are discussed in detail in dependence of the control parameters of the system.
Resonant Photovoltaic Effect in Surface State Electrons on Liquid Helium Denis KONSTANTINOV
Shepelyansky, Dima
-conductance oscillations, photovoltaic effect A nondegenerate two-dimensional electron system can be formed on the surfaceResonant Photovoltaic Effect in Surface State Electrons on Liquid Helium Denis KONSTANTINOV 1;2Ă, 2012; published online August 2, 2012) We observed an ultra-strong photovoltaic effect induced
Helium AtomSCF-LCAO Calculation of the (1s)2 Ground State of the
NSDL National Science Digital Library
Using a double-zeta basis of Slater-type orbitals [STOs], this Java applet calculates the single determinant singlet ground state 1s2 wavefunction of the helium atom. The doubly occupied orbital is expanded in terms of two basis functions, 1s and 1s`.
Excitation of autoionizing states of helium-like ions by scattering of high-energy particles
Mikhailov, A. I.; Mikhailov, I. A.; Nefiodov, A. V., E-mail: anef@thd.pnpi.spb.ru [B. P. Konstantinov Petersburg Nuclear Physics Institute (Russian Federation); Plunien, G. [Technische Universitaet Dresden, Institut fuer Theoretische Physik (Germany)] [Technische Universitaet Dresden, Institut fuer Theoretische Physik (Germany)
2013-03-15
The cross sections for two-electron excitations of helium-like atomic systems into the autoionizing 2s{sup 2} ({sup 1}S)- and 2p{sup 2} ({sup 1}S)-states by collisions with high-energy electrons and photons are deduced. The evaluations are performed to the leading order of non-relativistic perturbation theory. The analytical formulas for cross sections are obtained in the form of universal scalings. A comparison of our theoretical predictions with available theoretical and experimental results for the helium atom is made.
532-nm intensity-modulated optical lattice for driving Rydberg-Rydberg transitions
NASA Astrophysics Data System (ADS)
Maclennan, Jamie; Moore, Kaitlin; Ramos, Andira; Raithel, Georg
2015-05-01
We present progress towards implementing an experiment to make a precision measurement of the Rydberg constant using circular-state Rydberg atoms. An independent measurement of the Rydberg constant will contribute to solving discrepancies in fundamental physics, most notably the ``proton radius puzzle''. The experiment relies on driving a circular to near-circular, n = 51 to 53 Rydberg-Rydberg transition. This transition was chosen because it is insensitive to nuclear charge distribution and first-order Stark and Zeeman effects, yielding less uncertainty in a Rydberg constant measurement. The Rydberg atoms are trapped in a 532-nm optical lattice, which is intensity-modulated so that its temporal harmonics drive the microwave-frequency transitions, so-called ``ponderomotive spectroscopy.'' We have previously demonstrated ponderomotive spectroscopy using 1064-nm light modulated by a fiber-based electro-optic modulator (EOM). Here, the 532-nm light offers the benefit of a ``magic wavelength'' for the transition. Finding a method to prepare a tunable, high-power, intensity-modulated optical lattice at 532 nm presents a substantial challenge. Here, we report on progress in overcoming this challenge as well as on other recent experimental developments.
NASA Astrophysics Data System (ADS)
Carroll, Thomas J.; Fahey, Donald P.; Noel, Michael W.; Mellus, Alex; Ward, Jon
2012-06-01
Ultra-cold highly-excited atoms in a magneto-optical trap are strongly coupled by the dipole-dipole interaction. Rubidium atoms that have been excited to the 32d5/2, |mj| = 1/2 sublevel can exchange energy when an applied static electric field tunes the Stark states into resonance. They do so via the densely packed set of resonant interactions 32d+32d->34p+30g near 0.3 V/cm. Atoms that have exchanged energy and are now in the final p and manifold states can be coupled to a resonance involving 32d5/2, |mj| = 3/2 and 1/2 states, which redistributes population among the |mj| sublevels. We present experimental and computational studies that investigate this redistribution.
Ultracold chemistry of a single Rydberg atom in a BEC
NASA Astrophysics Data System (ADS)
Liebisch, Tara Cubel; Schlagmueller, Michael; Westphal, Karl Magnus; Kleinbach, Kathrin; Hermann, Udo; Nguyen, Huan; Boettcher, Fabian; Loew, Robert; Hofferberth, Sebastian; Pfau, Tilman; Perez-Rios, Jesus; Greene, Chris
2015-05-01
A single Rydberg excitation in the high density and low temperature environment of a Bose-Einstein condensate (BEC) leads to a fascinating testbed of low-energy electron-neutral and ion-neutral scattering. For a Rydberg state with a principal quantum number of 100, there are thousands of ground-state atoms with which the Rydberg electron interacts. In a BEC the interparticle spacing is at approximately the same length scale as the Langevin impact parameter, making it possible to study the effect of ion-neutral collisions on time scales much faster than the Rydberg lifetime. Collisions between the Rydberg electron and the ground state atoms cause a mean field density shift of the Rydberg line. We present results on how this effect can be used to monitor phase transitions of the BEC and probe thin density shells of the BEC to monitor density-dependent, ultracold chemical reactions. We report on experimental findings, of Rydberg state-changing collisions on ?s timescales, due to collisions of the Rydberg ionic core with neutral ground state atoms. We compare our findings to simulations based on classical trajectory calculations for the motion of the ionic core and neutral atoms, whereas the dynamics of the electron is treated quantum mechanically.
Density-functional calculations on singly and doubly excited Rydberg states of many-electron atoms
Chu, Shih-I; Roy, Amlan K.
2002-05-07
are in the error ranges 0.0090.632 % and 0.0851.600 %, respectively. The overall agreement of the present results is quite gratifying, especially in the light of DFTs difficulties in dealing with excited states. The exchange-only results are practically...
Dalkarov, O D
2015-01-01
A study of gravitational properties of matter presents a fundamental interest. The possibility of investigation of quantum gravitational states of matter by the example of helium atom is shown. The capability of the existence of helium quantum states in the gravitational field of a cold neutron star is examined. Observation of such states is done with the help of rotating neutron star's magnetic field. Periodically changing magnetic field induces transitions between gravitational states of helium atom and leads to the appearance of gravitational transitions' spectral lines in gigahertz frequency range.
The hyperfine structure of the ground states in the helium muonic atoms
Alexei M. Frolov
2012-07-19
The hyperfine structures of the ground states in the ${}^{3}$He$^{2+} \\mu^{-} e^{-}$ and ${}^{4}$He$^{2+} \\mu^{-} e^{-}$ helium-muonic atoms are investigated with the use of highly accurate variational wave functions. The differences between corresponding levels of hyperfine structure (i.e. hyperfine splittings) are determined to very high numerical accuracy. In particular, we have found that the hyperfine structure splitting in the ground state of the ${}^{4}$He$^{2+} \\mu^{-} e^{-}$ atom is $\\Delta \
Trapping Rydberg Atoms in an Optical Lattice
NASA Astrophysics Data System (ADS)
Anderson, Sarah E.
2012-06-01
Optical lattice traps for Rydberg atoms are of interest in advanced science and in practical applications. After a brief discussion of these areas of interest, I will review some basics of optical Rydberg-atom trapping. The trapping potential experienced by a Rydberg atom in an optical lattice is given by the spatial average of the free-electron ponderomotive energy weighted by the Rydberg electron's probability distribution. I will then present experimental results on the trapping of ^85Rb Rydberg atoms in a one-dimensional ponderomotive optical lattice (wavelength 1064 nm). The principal methods employed to study the lattice performance are microwave spectroscopy, which is used to measure the lattice's trapping efficiency, and photo-ionization, which is used to measure the dwell time of the atoms in the lattice. I have achieved a 90% trapping efficiency for ^85Rb 50S atoms by inverting the lattice immediately after laser excitation of ground-state atoms into Rydberg states. I have characterized the dwell time of the atoms in the lattice using photo-ionization of 50D5/2 atoms. In continued work, I have explored the dependence of the Rydberg-atom trapping potential on the angular portion of the atomic wavefunction. Distinct angular states exhibit different trapping behavior in the optical lattice, depending on how their wavefunctions are oriented relative to the lattice planes. Specifically, I have measured the lattice potential depth of sublevels of ^85Rb nD atoms (50<=n<=65) in a one-dimensional optical lattice with a transverse DC electric field. The trapping behavior varies substantially for the various angular sublevels, in agreement with theory. The talk will conclude with an outlook into planned experiments.
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.
Electromagnetically induced transparency and fluorescence in blockaded Rydberg atomic system
Li, Cheng; Zheng, Huaibin; Zhang, Zhaoyang; Yao, Xin; Zhang, Yunzhe; Zhang, Yiqi; Zhang, Yanpeng [Key Laboratory for Physical Electronics and Devices of the Ministry of Education and Shaanxi Key Lab of Information Photonic Technique, Xi'an Jiaotong University, Xi'an 710049 (China)] [Key Laboratory for Physical Electronics and Devices of the Ministry of Education and Shaanxi Key Lab of Information Photonic Technique, Xi'an Jiaotong University, Xi'an 710049 (China)
2013-10-28
We investigate the interaction between dark states and Rydberg excitation blockade by using electromagnetically induced transparency (EIT), fluorescence, and four-wave mixing (FWM) signals both theoretically and experimentally. By scanning the frequency detunings of the probe and dressing fields, respectively, we first observe these signals (three coexisting EIT windows, two fluorescence signals, and two FWM signals) under Rydberg excitation blockade. Next, frequency detuning dependences of these signals are obtained, in which the modulated results are well explained by introducing the dressing effects (leading to the dark states) with the corrected factor of the Rydberg excitation blockade. In addition, the variations by changing the principal quantum number n of Rydberg state shown some interesting phenomena resulting from Rydberg blockade are observed. The unique nature of such blockaded signals can have potential application in the demonstration of quantum computing.
Militzer, Burkhard
Equation of State Calculations of Hydrogen-Helium Mixtures in Solar and Extrasolar Giant Planets for hydrogen-helium mixtures at conditions of giant planet interiors of 0.2-2.3 g cm-3 and 1000-80000 K. INTRODUCTION The Kepler mission has provided us with over 2000 exo- planet candidates 1 that vary widely
Search for Positron Bound States in the Doubly Excited Region of the Helium Atom
NASA Astrophysics Data System (ADS)
Boadle, Roisin; Machacek, Joshua; Anderson, Emma; Sullivan, James; Buckman, Stephen
2012-10-01
Positron-atom binding has been the subject of many theoretical calculations in recent years. In these systems, a positron becomes temporarily bound to the atom, either through polarisation of the electronic charge cloud or formation of positronium (an e^-e^+ pair) which is weakly bound to the atom. There is now theoretical evidence of numerous positron-atom bound states, including for the helium atom. Ground state helium is incapable of binding a positron; however, recent calculations [1] have indicated that excited metastable states and doubly excited states may do so. These bound states might be expected to manifest themselves as structure in the energy dependence of the cross sections for processes such as total scattering, positronium formation, or ionization. We have carried out an experimental search for these positronic helium states in the doubly-excited region near 58 eV, using our high-resolution, trap-based positron beam. Results from this study will be presented and their ramifications discussed. [4pt] [1] M.J. Bromley and J. Mitroy Private Communication (2012)
Sharkey, Keeper L.; Bubin, Sergiy; Adamowicz, Ludwik
2011-05-21
Very accurate variational non-relativistic calculations are performed for four higher Rydberg {sup 2}D states (1s{sup 2}nd{sup 1}, n= 8, ..., 11) of the lithium atom ({sup 7}Li). The wave functions of the states are expanded in terms of all-electron explicitly correlated Gaussian functions and finite nuclear mass is used. The exponential parameters of the Gaussians are optimized using the variational method with the aid of the analytical energy gradient determined with respect to those parameters. The results of the calculations allow for refining the experimental energy levels determined with respect to the {sup 2}S 1s{sup 2}2s{sup 1} ground state.
Pattern formation of quantum jumps with Rydberg atoms
Lee, Tony E
2012-01-01
We study the nonequilibrium dynamics of quantum jumps in a one-dimensional chain of atoms. Each atom is driven on a strong transition to a short-lived state and on a weak transition to a metastable state. We choose the metastable state to be a Rydberg state so that when an atom jumps to the Rydberg state, it inhibits or enhances jumps in the neighboring atoms. This leads to rich spatiotemporal dynamics that are visible in the fluorescence of the strong transition. It also allows one to dissipatively prepare Rydberg crystals.
I. L. Hawk; D. L. Hardcastle
1976-01-01
The Schroedinger equation for S-type states of the helium atom, which is an elliptic partial-differential equation, is converted to a set of finite-difference equations, which are then solved by an iterative technique. The total energy of the ground state and first-excited state are calculated to be -2.90360 and -2.17414 a.u., respectively, as compared to the known accurate values of -2.90372
Yavuz, Deniz
Rabi Oscillations between Ground and Rydberg States with Dipole-Dipole Atomic Interactions T. A November 2007; published 19 March 2008) We demonstrate Rabi oscillations of small numbers of 87 Rb atoms interaction effects between as few as two atoms and by observation of coherent Rabi oscillations between
Narits, A. A. [Russian Academy of Sciences, Lebedev Physics Institute (Russian Federation)] [Russian Academy of Sciences, Lebedev Physics Institute (Russian Federation); Mironchuk, E. S. [Moscow Institute of Physics and Technology (State University) (Russian Federation)] [Moscow Institute of Physics and Technology (State University) (Russian Federation); Lebedev, V. S., E-mail: vlebedev@sci.lebedev.ru [Russian Academy of Sciences, Lebedev Physics Institute (Russian Federation)
2013-10-15
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.
NASA Astrophysics Data System (ADS)
Chluba, J.; Vasil, G. M.; Dursi, L. J.
2010-09-01
In this paper we discuss the effect of recombinations to highly excited states (n > 100) in hydrogen during the cosmological recombination epoch. For this purpose, we developed a new ordinary differential equation solver for the recombination problem, based on an implicit Gear's method. This solver allows us to include up to 350 l-resolved shells or ~61000 separate levels in the hydrogen model and to solve the recombination problem for one cosmology in ~27 h. This is a huge improvement in performance over our previous recombination code, for which a 100-shell computation (5050 separate states) already required ~150 h on a single processor. We show that for 350 shells down to redshift z ~ 200, the results for the free electron fraction have practically converged. The final modification in the free electron fraction at z ~ 200 decreases from about ?Ne/Ne ~ 2.8 per cent for 100 shells to ?Ne/Ne ~ 1.6 per cent for 350 shells. However, the associated changes in the cosmic microwave background power spectra at large multipoles l are rather small, so that for accurate computations in connection with the analysis of Planck data already ~100 shells are expected to be sufficient. Nevertheless, the total value of ? could still be affected at a significant level. We also briefly investigate the effect of collisions on the recombination dynamics. With our current estimates for the collisional rates we find a correction of ?Ne/Ne ~ -8.8 × 10-4 at z ~ 700, which is mainly caused by l-changing collisions with protons. Furthermore, we present results on the cosmological recombination spectrum, showing that at low frequencies collisional processes are important. However, the current accuracy of collisional rates is insufficient for precise computations of templates for the recombination spectrum at ? <~ 1GHz, and also the effect of collisions on the recombination dynamics suffers from the uncertainty in these rates. Improvements in collisional rates will therefore become necessary in order to obtain a final answer regarding their effects during recombination.
NASA Astrophysics Data System (ADS)
Gill, Alexander T.
Every day, millions of cubic feet of natural gas is transported through interstate pipelines and consumed by customers all over the United States of America. Gas distributors, responsible for sending natural gas to individual customers, are eager for an estimate of how much natural gas will be used in the near future. GasHour(TM) software, a reliable forecasting tool from the Marquette University GasDay(TM) lab, has been providing highly accurate hourly forecasts over the past few years. Our goal is to improve current GasHour forecasts, and my thesis presents an approach to achieve that using a blending technique. This thesis includes detailed explanations of the multi-horizon forecasting technique employed by GasHour models. Several graphs are displayed to reveal the structure of hourly forecasts from GasHour. We present SMHF (Smoothing Multi-horizon Forecasts), a step-by-step method showing how a polynomial smoothing technique is applied to current GasHour predications. A slightly different approach of smoothing has also been introduced. We compare RMSEs of both GasHour forecasts and smoothed ones. Different comparisons resulting from different situations have been demonstrated as well. Several conclusions have been reached. Based on the results, blending techniques can improve current GasHour forecasts. We look forward to applying this blending technique to other fields of forecasting.
Convergence properties of Fock's expansion for S-state eigenfunctions of the helium atom
John D. Morgan
1986-01-01
It is proved by functional analytic methods that for S-state solutions of Schrödinger's equation for the helium atom, Fock's expansion in powers of R1\\/2 and R ln R, where R is the hyperspherical radius r12+r22, converges pointwise for all R, thereby generalising a result of Macek that the expansion converges in the mean for all RE, Schrödinger's equation, considered as
Radiative Corrections to the Ground-State Energy of the Helium Atom
P. K. Kaibir; E. E. Salpeter
1957-01-01
The radiative corrections of relative order Z2alpha3 (absolute order Z4alpha3 ry), corresponding to the Lamb shift terms arising from the nuclear Coulomb potential, and some of the Zalpha3 corrections, arising from radiative interactions between the electrons, are calculated for the ground-state energy of the helium atom. The Z2alpha3 corrections are all calculated, but of the Zalpha3 corrections, which are expected
Spin squeezing in a Rydberg lattice clock.
Gil, L I R; Mukherjee, R; Bridge, E M; Jones, M P A; Pohl, T
2014-03-14
We theoretically demonstrate a viable approach to spin squeezing in optical lattice clocks via optical dressing of one clock state to a highly excited Rydberg state, generating switchable atomic interactions. For realistic experimental parameters, these interactions are shown to generate over 10 dB of squeezing in large ensembles within a few microseconds and without degrading the subsequent clock interrogation. PMID:24679291
Laser Spectroscopic Study on the Highly Excited States of Antiprotonic Helium
NASA Astrophysics Data System (ADS)
Kobayashi, T.; Barna, D.; Hayano, R. S.; Murakami, Y.; Todoroki, K.; Yamada, H.; Dax, A.; Venturelli, L.; Zurlo, N.; Horváth, D.; Aghai-Khozani, H.; Sótér, A.; Hori, M.
In this paper, we review the recent results on laser spectroscopy of antiprotonic helium (bar{p}He+) including the observation of the resonance transition (n,l) = (40,36) to (41,35) at a wavelength of 1154.9 nm. The decay rate of the population of bar{p}He+ in the resonance parent state (40,36) was found to be in good agreement with the theoretical radiative decay rate of that state. This implies that few metastable bar{p}He+ atoms are formed in the highly-excited states with n ? 41.
Photonic Controlled-Phase Gate Based on Rydberg Interactions
NASA Astrophysics Data System (ADS)
Khazali, Mohammadsadegh; Heshami, Khabat; Simon, Christoph
2015-03-01
Photons are ideal carriers of information in quantum communication. Since they do not interact, the implementation of deterministic photonic quantum computation depends on the creation of a non-permanent strong interaction between single photons. The implementation of neutral Rydberg atom gates inspired the development of photonic gates, using the coherent reversible mapping of the quantum states of photons onto highly interacting Rydberg atoms. Here we propose an interaction-based two-qubit gate between photons stored in Rydberg levels of an atomic ensemble. We perform a detailed study of errors due to the many-body interaction between Rydberg spin-waves, and we propose a compensation scheme for these errors. Furthermore we completely separate interaction and propagation by eliminating the Rydberg level from the storage process. Our proposed controlled-phase gate can achieve 99% fidelity with current technology.
R. Y. Chiao; S. J. Minter; K. Wegter-McNelly; L. A. Martinez
2010-11-02
Freely falling point-like objects converge toward the center of the Earth. Hence the gravitational field of the Earth is inhomogeneous, and possesses a tidal component. The free fall of an extended quantum mechanical object such as a hydrogen atom prepared in a high principal-quantum-number state, i.e. a circular Rydberg atom, is predicted to fall more slowly than a classical point-like object, when both objects are dropped from the same height above the Earth's surface. This indicates that, apart from transitions between quantum states, the atom exhibits a kind of quantum mechanical incompressibility during free fall in inhomogeneous, tidal gravitational fields like those of the Earth. A superconducting ring-like system with a persistent current circulating around it behaves like the circular Rydberg atom during free fall. Like the electronic wavefunction of the freely falling atom, the Cooper-pair wavefunction is quantum mechanically incompressible. The ions in the lattice of the superconductor, however, are not incompressible, since they do not possess a globally coherent quantum phase. The resulting difference during free fall in the response of the nonlocalizable Cooper pairs of electrons and the localizable ions to inhomogeneous gravitational fields is predicted to lead to a charge separation effect, which in turn leads to a large Coulomb force that opposes the convergence caused by the tidal gravitational force on the superconducting system. A "Cavendish-like" experiment is proposed for observing the charge separation effect induced by inhomogeneous gravitational fields in a superconducting circuit. The charge separation effect is determined to be limited by a pair-breaking process that occurs when low frequency gravitational perturbations are present.
Spin squeezing and supersolids using Rydberg-dressed strontium atoms
NASA Astrophysics Data System (ADS)
Jones, Matthew; Boddy, Danielle; Sadler, Daniel; Lochead, Graham; Bounds, Alistair; Adams, Charles; Bridge, Elizabeth
2014-05-01
Coherent excitation of cold atoms to Rydberg states provides a new platform for quantum many-body physics. We present new perspectives provided by divalent atoms such as strontium. We show that laser excitation of the second valence electron enables spatially, resolved state-selective detection of Rydberg atoms with single-atom sensitivity. Narrow intercombination lines enable two-photon excitation to the Rydberg state with low decoherence, providing an ideal system to investigate ``Rydberg dressing''. Here, a strong, off-resonant coupling to the Rydberg state introduces a new tunable, soft-core interaction between the atoms, with potential for the formation of a Rydberg supersolid phase. With the MPIPKS Dresden we show that applying this dressed interaction to strontium lattice clocks can also lead to the generation of significant squeezing that could be used to improve the signal-to-noise ratio. accepted for Phys. Rev. Lett. We present our experiments seeking to observe Rydberg dressing via intercombination lines in ultracold Sr atoms.
From molecular spectra to a density shift in dense Rydberg gases
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
Radiative and Relativistic Effects in the Decay of Highly-Excited States in Helium
NASA Astrophysics Data System (ADS)
Gorczyca, Thomas W.
2000-06-01
A recent experimental study(J.- E. Rubensson, C. Sĺthe, S. Cramm, B. Kessler, S. Stranges, R. Richter, M. Alagia, and M. Coreno, Phys. Rev. Lett. 83), 947 (1999) measured a significant fluorescence yield of the He(2l n l^') photoexcited resonances, showing major qualitative differences from non-relativistic predictions. We present a further theoretical analysis of these states, and perform detailed R-matrix multichannel quantum defect theory calculations, including radiative optical potential and spin-orbit frame transformation methods, to extract fluorescence and ionization cross sections, giving results in excellent agreement with new, higher-resolution measurements. The principal effect of the spin-orbit operator has been quantified as an oscillatory perturbation below threshold, causing strong mixing between all seven 2l nl^' J=1 resonance series, and redistribution of fluorescence and ionization cross sections at regular intervals. These results should be applicable for highly-excited states in general, whenever there are multiple Rydberg series capable of interacting, and emphasize that careful consideration of radiative and relativistic effects is necessary to characterize threshold spectra.
Rydberg excitation of a single trapped ion
Feldker, T; Stappel, M; Kolbe, D; Gerritsma, R; Walz, J; Schmidt-Kaler, F
2015-01-01
We demonstrate excitation of a single trapped cold $^{40}$Ca$^+$ ion to Rydberg levels by laser radiation in the vacuum-ultraviolet at 122 nm wavelength. Observed resonances are identified as 3d$^2$D$_{3/2}$ to 51 F, 52 F and 3d$^2$D$_{5/2}$ to 64F. We model the lineshape and our results imply a large state-dependent coupling to the trapping potential. Rydberg ions are of great interest for future applications in quantum computing and simulation, in which large dipolar interactions are combined with the superb experimental control offered by Paul traps.
Rydberg excitation of a single trapped ion
T. Feldker; P. Bachor; M. Stappel; D. Kolbe; R. Gerritsma; J. Walz; F. Schmidt-Kaler
2015-06-19
We demonstrate excitation of a single trapped cold $^{40}$Ca$^+$ ion to Rydberg levels by laser radiation in the vacuum-ultraviolet at 122 nm wavelength. Observed resonances are identified as 3d$^2$D$_{3/2}$ to 51 F, 52 F and 3d$^2$D$_{5/2}$ to 64F. We model the lineshape and our results imply a large state-dependent coupling to the trapping potential. Rydberg ions are of great interest for future applications in quantum computing and simulation, in which large dipolar interactions are combined with the superb experimental control offered by Paul traps.
Periodic-orbit spectra of hydrogen and helium
Qiu, Y.; Mueller, J.; Burgdoerfer, J. [Department of Physics, University of Tennessee, Knoxville, Tennessee 37996-1200 (United States)] [Department of Physics, University of Tennessee, Knoxville, Tennessee 37996-1200 (United States); [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6377 (United States)
1996-09-01
The semiclassical expression for the spectral density (Gutzwiller{close_quote}s trace formula) can be viewed as a Fourier expansion in terms of classical (quasi)periodic orbits. The inverse Fourier transform of the full quantum spectral density therefore not only gives the periodic orbit spectrum in the semiclassical limit, but may also provide a tool to characterize the quantum spectrum. We investigate the scaled energy Fourier transform spectrum of the hydrogen atom and doubly excited states of helium. For exactly solvable hydrogenic Rydberg spectra we study the {open_quote}{open_quote}window{close_quote}{close_quote} effect due to the finite length of the spectrum, the influence of resonance width, and of quantum defects. In helium a large number of periodic orbits including previously unknown orbits can be identified. {copyright} {ital 1996 The American Physical Society.}
Importance of considering helium excited states in He+ scattering by an aluminum surface
NASA Astrophysics Data System (ADS)
Iglesias-García, A.; García, Evelina A.; Goldberg, E. C.
2014-11-01
The He+/Al system is a very interesting projectile-surface combination which was thought initially as an example of a pure Auger neutralization mechanism. Then, because of the measured reionization explained by the antibonding interaction of the projectile state with the core target states, the resonant charge exchange with the band states was considered as another important contribution to the neutralization. Nevertheless, by only considering the neutralization to the ground state of helium, the measured ion survival probability is still overestimated. On the other hand, measurements of electron emission from an Al surface bombarded by He positive ions suggested the possibility of occupied excited states of helium due to the ion-surface collision. In this work, we also include the excited states of He within the time-dependent scattering process in which both neutralization mechanisms, resonant and Auger, are simultaneously contemplated. Our starting point is a multiorbital Anderson Hamiltonian projected over the selected space of ground and excited atomic configurations. An extra term related to the Auger mechanism is added to this Hamiltonian. A difference with previous works is that this approach includes the electron spin and, therefore, the spin fluctuation statistics in the charge-exchange process is correctly taken into account. We find a notable improvement in the agreement with the experiments and also that the interference between both mechanisms is not dramatic.
NASA Technical Reports Server (NTRS)
Taylor, Peter R.; Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.
1987-01-01
High quality ab initio electonic structure calculations were performed on the 2D Rydberg series in Al I. The configuration 3s3p2(2D) is shown to contribute substantially to the lowest four 2D Rydberg states. The same configuration also contributes substantially to a 2D state embedded in the ionization continuum. Computed oscillator strengths for the first six members of the 2D Rydberg transitions are given: these should be of substantially high accuracy than currently available values.
Two-stage Rydberg charge exchange: An efficient method for production of antihydrogen
Hessels, E.A. [Department of Physics and Astronomy, York University, Toronto, Ontario, M3J 1P3 (CANADA)] [Department of Physics and Astronomy, York University, Toronto, Ontario, M3J 1P3 (CANADA); Homan, D.M.; Cavagnero, M.J. [Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506-0055 (United States)] [Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506-0055 (United States)
1998-03-01
An efficient method for production of cold antihydrogen ({bar H}) is proposed. Alkali-metal atoms laser excited to a Rydberg state are charge exchanged with cold trapped positrons, producing Rydberg states of positronium. In a second Rydberg-state charge exchange, the positronium atoms give up their Rydberg positrons to cold trapped antiprotons, producing Rydberg states of {bar H}. These {bar H} atoms soon decay down to the ground state, and, because they are cold, could be trapped in a magnetic trap. The efficiency of the process results from the extremely large cross sections for Rydberg charge exchange. Classical trajectory Monte Carlo calculations indicate an {bar H} instantaneous production rate of 10{sup 6}/s. {copyright} {ital 1998} {ital The American Physical Society}
Carbon synthesis in steady-state hydrogen and helium burning on accreting neutron stars
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 (? ? 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(?, p){sup 17}F reaction rate introduces by far the largest uncertainties in the {sup 12}C yield.
Quantum optical non-linearities induced by Rydberg-Rydberg interactions: a perturbative approach
A. Grankin; E. Brion; E. Bimbard; R. Boddeda; I. Usmani; A. Ourjoumtsev; P. Grangier
2015-02-23
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 non-linearity 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. Therefore they allow us to investigate quantitatively new features associated with the resonant behaviour of the system. We also propose an effective non-linear 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.
a Theoretical Investigation of Doubly Excited States of the Helium Atom.
NASA Astrophysics Data System (ADS)
Cordes, Dietmar
The purpose of the present research is to develop a new method for applying hyperspherical coordinates, without the adiabatic hypothesis, in a variational basis consisting of Sturmian functions in the hyperradius R, Legendre polynomials in the angle separation Theta _{12}, and problem optimized functions in the pseudoangle alpha, in order to describe the characteristics of doubly excited states of the helium atom. In order to first gain insight into the suitability of our basis we have calculated energy values for the ground and three lowest excited singlet S states of helium. Plots of the deviation of our wave function from the true solution of the Schrodinger equation, (H - E)Phi(R,alpha,Theta _{12}), versus R and alpha are presented. We then applied a scattering variational principle to extract information on low lying doubly excited S states in helium converging to the n = 2 hydrogenic threshold of the residual ion. The resonances are described by our proposed basis of square integrable functions in hyperspherical coordinates. The continuum is treated by using positive-energy Coulomb functions on the energy shell. We present positions and widths of the lowest lying singlet and triplet S resonances along with their oscillator strengths to singlet and triplet P states ((1snp), n = 2,3,4). The background differential oscillator strength from the P states to the S continuum is also found and is very small. Computed branching ratios of nonradiative versus radiative transitions for these states indicate which state might be seen as a satellite line in an ion-atom collision experiment. Finally, we present a new theory for autoionizing states which are coupled to multiple continua via the concept of multi-channel configuration interaction in the continuum. The method is applied to the calculation of the partial cross sections for photoionization from the excited (1s 2p)^1P state in the vicinity of the (3,3a) ^1S and (3,3b) ^1S resonances, where the residual He^ {+} ion can be left in the 1s , 2s or 2p state. Results indicate a large probability of autoionization of the (3,3 a) ^1S state into the (1sks)^1S channel, whereas in the theoretical investigation of Ramaker and Schrader, which is the only existing reference, the (2 sks)^1S channel is preferred.
Ultrafast structural dynamics and isomerization in Rydberg-exited Quadricyclane
Rudakov, Fedor M [ORNL
2012-01-01
The quadricyclane - norbornadiene system is an important model for the isomerization dynamics between highly strained molecules. In a breakthrough observation for a polyatomic molecular system of that complexity, we follow the photoionization from Rydberg states in the time-domain to derive a measure for the time-dependent structural dynamics and the time-evolving structural dispersion even while the molecule is crossing electronic surfaces. The photoexcitation to the 3s and 3p Rydberg states deposits significant amounts of energy into vibrational motions. We observe the formation and evolution of the vibrational wavepacket on the Rydberg surface and the internal conversion from the 3p Rydberg states to the 3s state. In that state, quadricyclane isomerizes to norbornadiene with a time constant of {tau}{sub 2} = 136(45) fs. The lifetime of the 3p Rydberg state in quadricyclane is {tau}{sub 1} = 320(31) and the lifetime of the 3s Rydberg state in norbornadiene is {tau}{sub 3} = 394(32).
Three-body physics. Observation of the Efimov state of the helium trimer.
Kunitski, Maksim; Zeller, Stefan; Voigtsberger, Jörg; Kalinin, Anton; Schmidt, Lothar Ph H; Schöffler, Markus; Czasch, Achim; Schöllkopf, Wieland; Grisenti, Robert E; Jahnke, Till; Blume, Dörte; Dörner, Reinhard
2015-05-01
Quantum theory dictates that upon weakening the two-body interaction in a three-body system, an infinite number of three-body bound states of a huge spatial extent emerge just before these three-body states become unbound. Three helium (He) atoms have been predicted to form a molecular system that manifests this peculiarity under natural conditions without artificial tuning of the attraction between particles by an external field. Here we report experimental observation of this long-predicted but experimentally elusive Efimov state of (4)He3 by means of Coulomb explosion imaging. We show spatial images of an Efimov state, confirming the predicted size and a typical structure where two atoms are close to each other while the third is far away. PMID:25931554
Rotational state-changing cold collisions of hydroxyl ions with helium
Hauser, Daniel; Carelli, Fabio; Spieler, Steffen; Lakhmanskaya, Olga; Endres, Eric S; Kumar, Sunil S; Gianturco, Franco; Wester, Roland
2015-01-01
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 prohibitively 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 a...
Learning Approach on the Ground State Energy Calculation of Helium Atom
Shah, Syed Naseem Hussain
2010-07-28
This research investigated the role of learning approach on the ground state energy calculation of Helium atom in improving the concepts of science teachers at university level. As the exact solution of several particles is not possible here we used approximation methods. Using this method one can understand easily the calculation of ground state energy of any given function. Variation Method is one of the most useful approximation methods in estimating the energy eigen values of the ground state and the first few excited states of a system, which we only have a qualitative idea about the wave function.The objective of this approach is to introduce and involve university teacher in new research, to improve their class room practices and to enable teachers to foster critical thinking in students.
Excitation of the n=2 states of helium by positron impact
Caradonna, Peter; Sullivan, James P.; Jones, Adric; Makochekanwa, Casten; Slaughter, Daniel; Mueller, Dennis W.; Buckman, Stephen J. [ARC Centre for Antimatter-Matter Studies, Research School of Physics and Engineering, Australian National University Canberra, Australian Capital Territory 0200 (Australia)
2009-12-15
A high-resolution (DELTAEapprox55 meV) trap-based positron beam has been used to measure absolute scattering cross sections for the excitation of the resolved 2 {sup 1}S,P states of helium at energies between threshold and 38 eV. The experimental integral cross sections, which have typical uncertainties of 10% or less, are compared with several theoretical calculations, and the agreement is generally very favorable. In particular, a new convergent close-coupling approach shows excellent agreement with the experimental data.
Yang, Jijin [Carl Zeiss NTS, LLC, Peabody, MA (United States); Ferranti, David C [Carl Zeiss NTS, LLC, Peabody, MA (United States); Stern, Lewis A [Carl Zeiss NTS, LLC, Peabody, MA (United States); Sanford, Colin A [Carl Zeiss NTS, LLC, Peabody, MA (United States); Huang, Jason [Carl Zeiss NTS, LLC, Peabody, MA (United States); Ren, Zheng [Univ. of North Carolina, Chapel Hill, NC (United States). Dept. of Physics and Astronomy; Qin, Lu-Chang [Univ. of North Carolina, Chapel Hill, NC (United States). Dept. of Physics and Astronomy; Hall, Adam R [Univ. of North Carolina, Greensboro, NC (United States). Joint School of Nanoscience and Nanoengineering
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.
Prospects for fast Rydberg gates on an atom chip
Matthias M. Müller; Harald R. Haakh; Tommaso Calarco; Christiane P. Koch; Carsten Henkel
2011-04-14
Atom chips are a promising candidate for a scalable architecture for quantum information processing provided a universal set of gates can be implemented with high fidelity. The difficult part in achieving universality is the entangling two-qubit gate. We consider a Rydberg phase gate for two atoms trapped on a chip and employ optimal control theory to find the shortest gate that still yields a reasonable gate error. Our parameters correspond to a situation where the Rydberg blockade regime is not yet reached. We discuss the role of spontaneous emission and the effect of noise from the chip surface on the atoms in the Rydberg state.
Quantum Electrodynamic Corrections to the g Factor of Helium P States
M. Puchalski; U. D. Jentschura
2012-09-24
The Lande g factor describes the response of an atomic energy level to an external perturbation by a uniform and constant magnetic field. In the case of many-electron systems, the leading term is given by the interaction mu_B*(L+2S.B), where L and S are the orbital and spin angular momentum operators, respectively, summed over all electrons. For helium, a long-standing experimental-theoretical discrepancy for P states motivates a reevaluation of the higher-order terms which follow from relativistic quantum theory and quantum electrodynamics (QED). The tensor structure of relativistic corrections involves scalar, vector, and symmetric and anti-symmetric tensor components. We perform a tensorial reduction of these operators in a Cartesian basis, using an approach which allows us to separate the internal atomic from the external degrees of freedom (magnetic field) right from the start of the calculation. The evaluation proceeds in a Cartesian basis of helium eigenstates, using a weighted sum over the magnetic projections. For the relativistic corrections, this leads to a verification of previous results obtained using the Wigner-Eckhart theorem. The same method, applied to the radiative correction (Bethe logarithm term) leads to a spin-dependent correction which is different for singlet versus triplet P states. Theoretical predictions are given for singlet and triplet 2P and triplet 3P states and compared to experimental results where available.
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.
Closser, Kristina D; Gessner, Oliver; Head-Gordon, Martin
2014-04-01
The dynamics resulting from electronic excitations of helium clusters were explored using ab initio molecular dynamics. The simulations were performed with configuration interaction singles and adiabatic classical dynamics coupled to a state-following algorithm. 100 different configurations of He7 were excited into the 2s and 2p manifold for a total of 2800 trajectories. While the most common outcome (90%) was complete fragmentation to 6 ground state atoms and 1 excited state atom, 3% of trajectories yielded bound, He2(*), and <0.5% yielded an excited helium trimer. The nature of the dynamics, kinetic energy release, and connections to experiments are discussed. PMID:24712792
N. Nettelmann; B. Holst; A. Kietzmann; M. French; R. Redmer; D. Blaschke
2008-06-06
The equation of state of hydrogen, helium, and water effects interior structure models of giant planets significantly. We present a new equation of state data table, LM-REOS, generated by large scale quantum molecular dynamics simulations for hydrogen, helium, and water in the warm dense matter regime, i.e.for megabar pressures and temperatures of several thousand Kelvin, and by advanced chemical methods in the complementary regions. The influence of LM-REOS on the structure of Jupiter is investigated and compared with state-of-the-art results within a standard three-layer model consistent with astrophysical observations of Jupiter. Our new Jupiter models predict an important impact of mixing effects of helium in hydrogen with respect to an altered compressibility and immiscibility.
Hopkins, W Scott; Loock, Hans-Peter; Cronin, Bríd; Nix, Michael G D; Devine, Adam L; Dixon, Richard N; Ashfold, Michael N R; Yin, Hong-Ming; Rowling, Steven J; Büll, Alexander; Kable, Scott H
2008-10-01
In this paper, we report quantitative product state distributions for the photolysis of H2CO --> H + HCO in the triplet threshold region, specifically for several rotational states in the 2(2)4(3) and 2(3)4(1) H2CO vibrational states that lie in this region. We have combined the strengths of two complementary techniques, laser-induced fluorescence for fine resolution and H atom Rydberg tagging for the overall distribution, to quantify the upsilon, N, and Ka distributions of the HCO photofragment formed via the singlet and triplet dissociation mechanisms. Both techniques are in quantitative agreement where they overlap and provide calibration or benchmarks that permit extension of the results beyond that possible by each technique on its own. In general agreement with previous studies, broad N and Ka distributions are attributed to reaction on the S0 surface, while narrower distributions are associated with reaction on T1. The broad N and Ka distributions are modeled well by phase space theory. The narrower N and Ka distributions are in good agreement with previous quasi-classical trajectory calculations on the T1 surface. The two techniques are combined to provide quantitative vibrational populations for each initial H2CO vibrational state. For dissociation via the 2(3)4(1) state, the average product vibrational energy (15% of E(avail)) was found to be about half of the rotational energy (30% of E(avail)), independent of the initial H2CO rotational state, irrespective of the singlet or triplet mechanism. For dissociation via the 2(2)4(3) state, the rotational excitation remained about 30% of E(avail), but the vibrational excitation was reduced. PMID:18710191
XUV frequency-comb metrology on the ground state of helium
Kandula, Dominik Z.; Gohle, Christoph; Pinkert, Tjeerd J.; Ubachs, Wim; Eikema, Kjeld S. E. [LaserLaB Amsterdam, VU University, De Boelelaan 1081, NL-1081HV Amsterdam (Netherlands)
2011-12-15
The operation of a frequency comb at extreme ultraviolet (xuv) wavelengths based on pairwise amplification and nonlinear upconversion to the 15th harmonic of pulses from a frequency-comb laser in the near-infrared range is reported. It is experimentally demonstrated that the resulting spectrum at 51 nm is fully phase coherent and can be applied to precision metrology. The pulses are used in a scheme of direct-frequency-comb excitation of helium atoms from the ground state to the 1s4p and 1s5p {sup 1} P{sub 1} states. Laser ionization by auxiliary 1064 nm pulses is used to detect the excited-state population, resulting in a cosine-like signal as a function of the repetition rate of the frequency comb with a modulation contrast of up to 55%. Analysis of the visibility of this comb structure, thereby using the helium atom as a precision phase ruler, yields an estimated timing jitter between the two upconverted-comb laser pulses of 50 attoseconds, which is equivalent to a phase jitter of 0.38 (6) cycles in the xuv at 51 nm. This sets a quantitative figure of merit for the operation of the xuv comb and indicates that extension to even shorter wavelengths should be feasible. The helium metrology investigation results in transition frequencies of 5 740 806 993 (10) and 5 814 248 672 (6) MHz for excitation of the 1s4p and 1s5p {sup 1} P{sub 1} states, respectively. This constitutes an important frequency measurement in the xuv, attaining high accuracy in this windowless part of the electromagnetic spectrum. From the measured transition frequencies an eight-fold-improved {sup 4}He ionization energy of 5 945 204 212 (6) MHz is derived. Also, a new value for the {sup 4}He ground-state Lamb shift is found of 41 247 (6) MHz. This experimental value is in agreement with recent theoretical calculations up to order m{alpha}{sup 6} and m{sup 2}/M{alpha}{sup 5}, but with a six-times-higher precision, therewith providing a stringent test of quantum electrodynamics in bound two-electron systems.
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.
Apparatus for excitation and detection of Rydberg atoms in quantum gases
Robert Loew; Ulrich Raitzsch; Rolf Heidemann; Vera Bendkowsky; Bjoern Butscher; Axel Grabowski; Tilman Pfau
2007-06-18
We present and characterize a versatile experimental setup which allows for excitation and detection of Rydberg atoms in quantum gases. The novel concept of the setup features two charged particle detectors and eight electrical field plates inside the vacuum chamber, which allows the detection and manipulation of Rydberg atoms. The setup presented here is applicable to all atomic species used in the field of quantum gases. We describe and characterize the production of Bose-Einstein condensates, the excitation scheme into Rydberg states, the detection of Rydberg states by field ionization followed by ion detection and the various electric field configurations provided by the eight field plates.
P. T. Greenland; R. Thürwächter
1993-01-01
The Born-Oppenheimer approximation is used to discuss the high rotational and vibrational state of the (He p?)e? system in the electronic 1s? and 2p? states. Very high angular momentum states, in which the antiproton is well outside the\\u000a electron orbit, have a Rydberg-like character. states in which the antiproton is within the 1s? electron orbit have enhanced\\u000a radiative lifetimes due
Quantum Simulation of Helium Hydride Cation in a Solid-State Spin Register.
Wang, Ya; Dolde, Florian; Biamonte, Jacob; Babbush, Ryan; Bergholm, Ville; Yang, Sen; Jakobi, Ingmar; Neumann, Philipp; Aspuru-Guzik, Alán; Whitfield, James D; Wrachtrup, Jörg
2015-08-25
Ab initio computation of molecular properties is one of the most promising applications of quantum computing. While this problem is widely believed to be intractable for classical computers, efficient quantum algorithms exist which have the potential to vastly accelerate research throughput in fields ranging from material science to drug discovery. Using a solid-state quantum register realized in a nitrogen-vacancy (NV) defect in diamond, we compute the bond dissociation curve of the minimal basis helium hydride cation, HeH(+). Moreover, we report an energy uncertainty (given our model basis) of the order of 10(-14) hartree, which is 10 orders of magnitude below the desired chemical precision. As NV centers in diamond provide a robust and straightforward platform for quantum information processing, our work provides an important step toward a fully scalable solid-state implementation of a quantum chemistry simulator. PMID:25905564
Truhlar, Donald G
electronic excitation energies of valence, Rydberg, and charge-transfer states and potential energies near functionals for time-dependent density functional theory calculations of valence and Rydberg electronic for predicting electronic excitation energies of valence, Rydberg, and charge-transfer states and potential
Asymptotic methods for Rydberg transitions
NASA Astrophysics Data System (ADS)
Dewangan, D. P.
2012-02-01
Quantum mechanical expressions of several important physical quantities like the hydrogen dipole matrix elements, line strength and form factors for several excitation processes have long been available in the literature in terms of the terminating hypergeometric functions but calculations from these expressions generally present serious numerical problems for large principal quantum numbers n and n?. Determination of asymptotic and other appropriate approximations of these quantities for large n and n? has for long been posing challenge. We discuss a recent method that transforms the terminating hypergeometric functions into the Jacobi polynomials and exploits the properties of the Jacobi polynomials to provide a solution to the problem of the evaluation of these physical quantities. A noteworthy result of this method is that the exploitation of the recurrence relation of the Jacobi polynomials permits exact numerical calculations for various Rydberg processes for so large n,n?2000 for which computation was usually not possible earlier. Another noteworthy outcome is that the method readily leads to a strikingly accurate expression of a Rydberg matrix element between nearby Rydberg states in terms of the Bessel functions, called an NRS-formula, which also helps to solve, without any recourse to classical and semiclassical arguments, a long standing problem of how to consistently derive the formula of classical mechanics obtained earlier by invoking the correspondence principle. The numerical results from the exact and approximate formulae of various quantum matrix elements presented in the article are so extensive that they reveal how various formulae including those of the correspondence principle convergence to their respective exact quantum expressions. Also, for numerical and analytical study of various matrix elements involving states lying near the continuum threshold, which have posed problems earlier, simpler quantum expressions are presented. The quantum expressions presented in the article provide nearly complete solutions over the hydrogenic bound-state spectrum for the calculation of several physical quantities like the radial dipole matrix element, line strength and form factors for transitions between arbitrary s states and between arbitrary circular states.
Rydberg atoms in hollow-core photonic crystal fibres
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 atomssix orders of magnitude higher than ground-state atomsmakes 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
Proposed method for laser spectroscopy of pionic helium atoms to determine the charged-pion mass
Masaki Hori; Anna Sótér; Vladimir I. Korobov
2014-04-30
Metastable pionic helium ($\\pi{\\rm He}^+$) is a three-body atom composed of a helium nucleus, an electron occupying the $1s$ ground state, and a negatively charged pion $\\pi^-$ in a Rydberg state with principal- and orbital angular momentum quantum numbers of $n\\sim \\ell+1\\sim 16$. We calculate the spin-independent energies of the $\\pi{\\rm ^3He}^+$ and $\\pi{\\rm ^4He}^+$ isotopes in the region $n=15$--19. These include relativistic and quantum electrodynamics corrections of orders $R_{\\infty}\\alpha^2$ and $R_{\\infty}\\alpha^3$ in atomic units, where $R_{\\infty}$ and $\\alpha$ denote the Rydberg and fine structure constants. The fine-structure splitting due to the coupling between the electron spin and the orbital angular momentum of the $\\pi^-$, and the radiative and Auger decay rates of the states are also calculated. Some states $(n,\\ell)=(16,15)$ and $(17,16)$ retain nanosecond-scale lifetimes against $\\pi^-$ absorption into the helium nucleus. We propose to use laser pulses to induce $\\pi^-$ transitions from these metastable states, to states with large ($\\sim 10^{11}$ s$^{-1}$) Auger rates. The $\\pi{\\rm He}^{2+}$ ion that remains after Auger emission of the $1s$ electron undergoes Stark mixing with the $s$, $p$, and $d$ states during collisions with the helium atoms in the experimental target. This leads to immediate nuclear absorption of the $\\pi^-$. The resonance condition between the laser beam and the atom is thus revealed as a sharp spike in the rates of neutrons, protons, deuterons, and tritons that emerge....(continued)
Discrete Self-Similarity Between RR Lyrae Stars And Singly-Excited Helium Atoms
R. L. Oldershaw
2008-03-29
Classical variable stars called RR Lyrae stars have pulsating outer envelopes comprised of excited atoms. Here we demonstrate that the qualitative and quantitative properties of RR Lyrae variables and one subclass of their atomic scale constituents: singly-excited helium atoms undergoing transitions between Rydberg states, share a remarkable degree of self-similarity. In terms of masses, radii, oscillation periods, morphologies and kinematics the stellar and atomic analogues obey a simple set of discrete self-similar scaling equations. The concept of stellar/atomic self-similarity may prove useful in the search for a deeper understanding of both stellar and atomic systems.
Probing a quantum gas with single Rydberg atoms
Nguyen, Huan; Schlagmüller, Michael; Lochead, Graham; Westphal, Karl M; Löw, Robert; Hofferberth, Sebastian; Pfau, Tilman
2015-01-01
We present a novel spectroscopic method for probing the \\insitu~density of quantum gases. We exploit the density-dependent energy shift of highly excited {Rydberg} states, which is of the order $10$\\MHz\\,/\\,1E14\\,cm$^{\\text{-3}}$ for \\rubidium~for triplet s-wave scattering. The energy shift combined with a density gradient can be used to localize Rydberg atoms in density shells with a spatial resolution less than optical wavelengths, as demonstrated by scanning the excitation laser spatially across the density distribution. We use this Rydberg spectroscopy to measure the mean density addressed by the Rydberg excitation lasers, and to monitor the phase transition from a thermal gas to a Bose-Einstein condensate (BEC).
Entanglement of Qubits Encoded in Cesium Atoms via Rydberg Dressing
NASA Astrophysics Data System (ADS)
Jau, Yuan-Yu; Hankin, Aaron; Keating, Tyler; Deutsch, Ivan; Biedermann, Grant
2015-05-01
Neutral-atom qubits are normally encoded in the ground-state sublevels for long coherent operations, but strong, tunable long-range interactions between ground-state neutral atoms are difficult to achieve. By applying off-resonant Rydberg excitation lasers to the atoms, we can in principle generate Rydberg-dressed, AC-Stark shifted qubit or spin states. Owing to the electric dipole-dipole interactions (EDDI) between atoms in the Rydberg states, different collective qubit states can acquire different AC Stark shifts, which cause effective interactions between qubits. On the other hand, transition blockades between collective qubit states also occur. We have experimentally demonstrated a strong ground-state interaction strength (~ MHz) between the two singly trapped, Rydberg-dressed Cs atoms. With a transition blockade between the two-qubit states due to Rydberg dressing, we are able to produce Bell-state entanglements of with >80% fidelity excluding the atom loss event. The two-atom survival (no loss) probability is 74% with about 10 Hz data rate. This gives us about 6 entangled qubit pair per second.
Militzer, Burkhard
Ab Initio Equation of State for Hydrogen-Helium Mixtures with Recalibration of the Giant-Planet-temperature conditions typical of giant planet interiors, 0.2-9 g cm-3 and 1000-80 000 K for a typical helium mass thermal state of giant planets with known values for mass and radius. Changes are most pronounced
Nonzero angular momentum states of the helium atom in a strong magnetic field
Wolfgang Becken; Peter Schmelcher
2000-06-07
The electronic structure of the helium atom in the magnetic field regime B=0-100a.u. is investigated, using a full configuration interaction approach which is based on a nonlinearly optimized anisotropic Gaussian basis set of one-particle functions. The corresponding generalized eigenvalue problem is solved for the magnetic quantum number M=-1 and for both even and odd z-parity as well as singlet and triplet spin symmetry. Accurate total electronic energies of the ground state and the first four excitations in each subspace as well as their one-electron ionization energies are presented as a function of the magnetic field. Additionally we present energies for electromagnetic transitions within the M=-1 subspace and between the M=-1 subspace and the M=0 subspace treated in a previous work. A complete table of wavelengths and field strengths for the detected stationary points is given.
Rubidium D1 and D2 atomic lines pressure broadened by ground-state helium atoms
NASA Astrophysics Data System (ADS)
Bouhadjar, F.; Alioua, K.; Bouazza, M. T.
2014-09-01
Full quantum calculations are performed to determine the spectral broadening of the rubidium D1 and D2 lines induced by collisions with helium perturbers. The potential curves of the low-lying RbHe molecular states, as well as the corresponding transition dipole moments, are generated theoretically with ab initio methods based on SA-CASSCF-MRCI calculations, including the spin-orbit effects. The absorption and emission coefficients at wavelengths lying between 650 and 950\\;nm and temperatures ranging from 100 to 3000 K are determined. The absorption profile reveals it is dominated by the free-free transitions, whereas the emission spectral shape arises from the free-free and bound-free transitions. The resulting red- and blue-wing profiles are compared with previous experimental and theoretical works.
One-dimensional quantum Rydberg gases in a magneto-electric trap
Mayle, Michael; Lesanovsky, Igor; Schmelcher, Peter
2007-01-01
We study the quantum properties of Rydberg atoms in a magnetic Ioffe-Pritchard trap which is superimposed by a homogeneous electric field. Trapped Rydberg atoms can be created in long-lived electronic states exhibiting a permanent electric dipole moment of several hundred Debye. The resulting dipole-dipole interaction in conjunction with the radial confinement is demonstrated to give rise to an effectively one-dimensional ultracold quantum Rydberg gas with a macroscopic interparticle distance. We derive analytical expressions for the electric dipole moment and the critical linear density of Rydberg atoms.
Giant Cross Section for Molecular Ion Formation in Ultracold Rydberg Gases
NASA Astrophysics Data System (ADS)
Niederprüm, Thomas; Thomas, Oliver; Manthey, Torsten; Weber, Tobias M.; Ott, Herwig
2015-07-01
We have studied the associative ionization of a Rydberg atom and a ground-state atom in an ultracold Rydberg gas. The measured scattering cross section is 3 orders of magnitude larger than the geometrical size of the produced molecule. This giant enhancement of the reaction kinetics is due to an efficient directed mass transport which is accelerated by the Rydberg electron. We also find that the total inelastic scattering cross section is given by the geometrical size of the Rydberg electron's wave function.
Observation of the stark-tuned Förster resonance between two Rydberg atoms.
Ryabtsev, I I; Tretyakov, D B; Beterov, I I; Entin, V M
2010-02-19
Cold atoms in highly excited Rydberg states are promising candidates to implement quantum logic gates of a quantum computer via long-range dipole-dipole interaction. Two-qubit gates require a controlled interaction of only two close Rydberg atoms. We report on the first spectroscopic observation of the resonant dipole-dipole interaction between two cold rubidium Rydberg atoms confined in a small laser excitation volume. The interaction strength was controlled by fine-tuning of the Rydberg levels into a Förster resonance using the Stark effect. The observed resonance line shapes are in good agreement with numerical Monte Carlo simulations. PMID:20366877
Optical spectroscopy of rubidium Rydberg atoms with a 297 nm frequency-doubled dye laser.
Thoumany, P; Hänsch, T; Stania, G; Urbonas, L; Becker, Th
2009-06-01
We demonstrate Doppler-free, purely optical detection of laser-excited rubidium Rydberg atoms in a room-temperature gas cell. The Rydberg atoms are excited with a frequency-doubled dye laser at 297 nm in a single-excitation step from the ground state; the detection is performed with a 780 nm diode laser in a scheme similar to electron shelving. Laser spectroscopy of Rydberg transitions is demonstrated, and a frequency-doubled dye is stabilized to one Rydberg transition in the UV. The performance of this stabilization is measured with an atomic-beam apparatus and a time of flight experiment. PMID:19488127
High Resolution Rydberg Spectroscopy of ultracold Rubidium Atoms
Axel Grabowski; Rolf Heidemann; Robert Löw; Jürgen Stuhler; Tilman Pfau
2005-08-10
We present experiments on two-photon excitation of ${\\rm ^{87}}$Rb atoms to Rydberg states. For this purpose, two continuous-wave (cw)-laser systems for both 780 nm and 480 nm have been set up. These systems are optimized to a small linewidth (well below 1 MHz) to get both an efficient excitation process and good spectroscopic resolution. To test the performance of our laser system, we investigated the Stark splitting of Rydberg states. For n=40 we were able to see the hyperfine levels splitting in the electrical field for different finestructure states. To show the ability of spatially selective excitation to Rydberg states, we excited rubidium atoms in an electrical field gradient and investigated both linewidths and lineshifts. Furthermore we were able to excite the atoms selectively from the two hyperfine ground states to Rydberg states. Finally, we investigated the Autler-Townes splitting of the 5S$_{1/2}$$\\to$5P$_{3/2}$ transition via a Rydberg state to determine the Rabi frequency of this excitation step.
Militzer, Burkhard
2008-01-01
of State of Solid Helium S. A. Khairallah1 and B. Militzer1,2 Departments of Earth and Planetary Science1 to be present in the outer layers of white dwarfs (WD) [3]. After the initial star has exhausted all its nuclear fuel, it sheds its outer layer and leaves behind a dense carbon-oxygen core of the size of the earth
M. J. Slaman; R. A. Aziz
1991-01-01
Second virial coefficients and transport properties of helium are presented based on a state-of-the-art interatomic potential which was constructed with the use of a multiproperty fit. The experimental potential employed to produce these properties accurately reproduces a wide range of bulk and microscopic data and agrees well with ab initio calculations which were not available at the time of its
Eisfeld, Alexander
Excitation transport through Rydberg dressing This article has been downloaded from IOPscience through Rydberg dressing S Wüster1 , C Ates, A Eisfeld and J M Rost Max Planck Institute for the Physics. The scheme uses off-resonant dressing with atomic Rydberg states. We demonstrate coherent migration
Measurement of the oscillator strength distribution in helium
Hussain, Shahid; Saleem, M.; Baig, M. A.
2007-07-15
The oscillator strength distribution in the discrete and continuous regions of the spectrum of helium from the 2s {sup 1}S{sub 0} metastable state has been determined using a Nd: yttrium aluminum garnet (YAG) pumped dye laser system in conjunction with a low pressure rf glow discharge. The saturation technique has been employed to determine the photoionization cross section from the 2s {sup 1}S{sub 0} excited state at and above the first ionization threshold. The measured value of the photoionization cross section at the ionization threshold has been used to extract the f values for the 2s {sup 1}S{yields}np {sup 1}P Rydberg series from n=10 to n=52. The f values of the observed Rydberg series decrease smoothly with an increase of the principal quantum number. In the continuum region the oscillator strength densities have been estimated by measuring the photoionization cross sections from the 2s {sup 1}S{sub 0} excited state at five ionizing laser wavelengths above the first ionization threshold. The discrete f values smoothly merge into the continuous oscillator strength densities across the ionization threshold.
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.
Dynamic dipole polarizabilities for the low-lying triplet states of helium
NASA Astrophysics Data System (ADS)
Zhang, Yong-Hui; Tang, Li-Yan; Zhang, Xian-Zhou; Shi, Ting-Yun
2015-07-01
The dynamic dipole polarizabilities for the four lowest triplet states (2 3S , 3 3S , 2 3P , and 3 3P ) of helium are calculated using the B -spline configuration interaction method. Present values of the static dipole polarizabilities in the length, velocity, and acceleration gauges are in good agreement with the best Hylleraas results. Also the tune-out wavelengths in the range 400 nm-4.2 ? m for the four lowest triplet states are identified, and the magic wavelengths in the range 460 nm-3.5 ? m for the 2 3S ?3 3S , 2 3S ?2 3P , and 2 3S ?3 3P transitions are determined. We show that the tune-out wavelength of 2 3S state is 413.038 28 (3 ) nm, which corroborates the value of Mitroy and Tang [Phys. Rev. A 88, 052515 (2013), 10.1103/PhysRevA.88.052515], and the magic wavelength around 1066 nm for the 2 3S ?3 3P transition can be expected for precision measurement to determine the ratio of transition matrix elements (2 3S ?2 3P ) /(3 3P ?6 3S ) .
NASA Astrophysics Data System (ADS)
Colombo, Anthony P.; Zhou, Yan; Prozument, Kirill; Coy, Stephen L.; Field, Robert W.
2013-01-01
We apply the chirped-pulse millimeter-wave (CPmmW) technique to transitions between Rydberg states in calcium atoms. The unique feature of Rydberg-Rydberg transitions is that they have enormous electric dipole transition moments (5 kiloDebye at n* 40, where n* is the effective principal quantum number), so they interact strongly with the mm-wave radiation. After polarization by a mm-wave pulse in the 70-84 GHz frequency region, the excited transitions re-radiate free induction decay (FID) at their resonant frequencies, and the FID is heterodyne-detected by the CPmmW spectrometer. Data collection and averaging are performed in the time domain. The spectral resolution is 100 kHz. Because of the large transition dipole moments, the available mm-wave power is sufficient to polarize the entire bandwidth of the spectrometer (12 GHz) in each pulse, and high-resolution survey spectra may be collected. Both absorptive and emissive transitions are observed, and they are distinguished by the phase of their FID relative to that of the excitation pulse. With the combination of the large transition dipole moments and direct monitoring of transitions, we observe dynamics, such as transient nutations from the interference of the excitation pulse with the polarization that it induces in the sample. Since the waveform produced by the mm-wave source may be precisely controlled, we can populate states with high angular momentum by a sequence of pulses while recording the results of these manipulations in the time domain. We also probe the superradiant decay of the Rydberg sample using photon echoes. The application of the CPmmW technique to transitions between Rydberg states of molecules is discussed.
Colombo, Anthony P.; Zhou Yan; Prozument, Kirill; Coy, Stephen L.; Field, Robert W.
2013-01-07
We apply the chirped-pulse millimeter-wave (CPmmW) technique to transitions between Rydberg states in calcium atoms. The unique feature of Rydberg-Rydberg transitions is that they have enormous electric dipole transition moments ({approx}5 kiloDebye at n*{approx} 40, where n* is the effective principal quantum number), so they interact strongly with the mm-wave radiation. After polarization by a mm-wave pulse in the 70-84 GHz frequency region, the excited transitions re-radiate free induction decay (FID) at their resonant frequencies, and the FID is heterodyne-detected by the CPmmW spectrometer. Data collection and averaging are performed in the time domain. The spectral resolution is {approx}100 kHz. Because of the large transition dipole moments, the available mm-wave power is sufficient to polarize the entire bandwidth of the spectrometer (12 GHz) in each pulse, and high-resolution survey spectra may be collected. Both absorptive and emissive transitions are observed, and they are distinguished by the phase of their FID relative to that of the excitation pulse. With the combination of the large transition dipole moments and direct monitoring of transitions, we observe dynamics, such as transient nutations from the interference of the excitation pulse with the polarization that it induces in the sample. Since the waveform produced by the mm-wave source may be precisely controlled, we can populate states with high angular momentum by a sequence of pulses while recording the results of these manipulations in the time domain. We also probe the superradiant decay of the Rydberg sample using photon echoes. The application of the CPmmW technique to transitions between Rydberg states of molecules is discussed.
Spectroscopic Observation of Resonant Electric Dipole-Dipole Interactions between Cold Rydberg Atoms
Martin, James D. D.
Atoms K. Afrousheh, P. Bohlouli-Zanjani, D. Vagale, A. Mugford, M. Fedorov, and J. D. D. Martin between cold Rydberg atoms were observed using microwave spectroscopy. Laser-cooled 85Rb atoms pulse transferred a fraction of these Rydberg atoms to the 46p3=2 state. A second microwave pulse
Menzel, A.
1996-05-01
The double excitations of helium offers an ideal case for investigating electron dynamics in a three-body system. The author`s study of the He {sup 1}P{sup o} double excitations comprises measurements of the partial photoionization cross sections {sigma}{sub n}(He{sup +}) and the partial photoelectron angular distribution parameters {beta}{sub n} for the series N(K,T){sub i}{sup A} up to the N=5 threshold. The experiment was peformed at the ALS undulator beam line 9.0.1., which provided a photon flux of 2 x 10{sup 12} photons per second with a small photon energy bandpass of 7 to 12 meV. This level of differentiation, along with the small bandpass, offers the most critical assessment of the dynamics of the two-electron excitations to date. The principal series K = N {minus} 2 are clearly delineated in both {sigma}{sub n} and {beta}{sub n}. The {beta}{sub n} show all minor series with N = K {minus} 4 very clearly, in contrast to measurements of the total absorption cross section. Excellent accord between experiment and theory, particularly the hyperspherical close-coupling method, was found for the dynamic properties in all instances, including the interference pattern due to an overlap of N = 5 and N = 6 series members. Generally, the Rydberg series of resonance-induced profiles vary greatly depending on the final ionic state He{sup +}(n), whereas the peak-to-valley variation in the {sigma}{sub n} within a given series N is of similar magnitude for all n. Interestingly, a striking systematic trend is noted through the various series: the resonance-induced profiles for both the {sigma}{sub n} and {beta}{sub n} of the photoelectron satellites are virtually identical provided the final ionic state He{sup +}(n), n {ge} 2, is reached via an excited series N with {Delta} = 1, or {Delta} = 2, where {Delta} = N = n. This overall pattern might be attributed to the general similarity of states with the same set of approximately good quantum numbers (n {minus} K), A, and T.
Dipolar Rydberg-atom gas prepared by adiabatic passage through an avoided crossing
NASA Astrophysics Data System (ADS)
Wang, Limei; Zhang, Hao; Zhang, Linjie; Li, Changyong; Yang, Yonggang; Zhao, Jianming; Raithel, Georg; Jia, Suotang
2015-06-01
The passage of cold cesium 49S1/2 Rydberg atoms through an electric-field-induced multi-level avoided crossing with nearby hydrogen-like Rydberg levels is employed to prepare a cold, dipolar Rydberg atom gas. When the electric field is ramped through the avoided crossing on time scales on the order of 100 ns or slower, the 49S1/2 population adiabatically transitions into high-l Rydberg Stark states. The adiabatic state transformation results in a cold gas of Rydberg atoms with large electric dipole moments. After a waiting time of about 1 ?s and at sufficient atom density, the adiabatically transformed highly dipolar atoms become undetectable, enabling us to discern adiabatic from diabatic passage behavior through the avoided crossing. We attribute the state-selectivity to m-mixing collisions between the dipolar atoms. The data interpretation is supported by numerical simulations of the passage dynamics and of binary m-mixing collisions.
Two-Atom Rydberg Blockade using Direct 6S to nP Excitation
A. M. Hankin; Y. -Y. Jau; L. P. Parazzoli; C. W. Chou; D. J. Armstrong; A. J. Landahl; G. W. Biedermann
2014-04-21
We explore a single-photon approach to Rydberg state excitation and Rydberg blockade. Using detailed theoretical models, we show the feasibility of direct excitation, predict the effect of background electric fields, and calculate the required interatomic distance to observe Rydberg blockade. We then measure and control the electric field environment to enable coherent control of Rydberg states. With this coherent control, we demonstrate Rydberg blockade of two atoms separated by 6.6(3) {\\mu}m. When compared with the more common two-photon excitation method, this single-photon approach is advantageous because it eliminates channels for decoherence through photon scattering and AC Stark shifts from the intermediate state while moderately increasing Doppler sensitivity.
Two-Atom Rydberg Blockade using a Single-Photon Transition
Hankin, A M; Parazzoli, L P; Chou, C W; Armstrong, D J; Landahl, A J; Biedermann, G W
2014-01-01
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) {\\mu}m. When compared with the more common two-photon excitation method, this single-photon approach is advantageous because it eliminates channels for decoherence through photon scattering and AC Stark shifts from the intermediate state while moderately increasing Doppler sensitivity.
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) ?m. When compared with the more common two-photon excitation method, this single-photon approach is advantageous because it eliminates channels for decoherence through photon scattering and ac Stark shifts from the intermediate state while moderately increasing Doppler sensitivity.
Microscopic Characterization of Scalable Coherent Rydberg Superatoms
NASA Astrophysics Data System (ADS)
Zeiher, Johannes; Schauß, Peter; Hild, Sebastian; Macr?, Tommaso; Bloch, Immanuel; Gross, Christian
2015-07-01
Strong interactions can amplify quantum effects such that they become important on macroscopic scales. Controlling these coherently on a single-particle level is essential for the tailored preparation of strongly correlated quantum systems and opens up new prospects for quantum technologies. Rydberg atoms offer such strong interactions, which lead to extreme nonlinearities in laser-coupled atomic ensembles. As a result, multiple excitation of a micrometer-sized cloud can be blocked while the light-matter coupling becomes collectively enhanced. The resulting two-level system, often called a "superatom," is a valuable resource for quantum information, providing a collective qubit. Here, we report on the preparation of 2 orders of magnitude scalable superatoms utilizing the large interaction strength provided by Rydberg atoms combined with precise control of an ensemble of ultracold atoms in an optical lattice. The latter is achieved with sub-shot-noise precision by local manipulation of a two-dimensional Mott insulator. We microscopically confirm the superatom picture by in situ detection of the Rydberg excitations and observe the characteristic square-root scaling of the optical coupling with the number of atoms. Enabled by the full control over the atomic sample, including the motional degrees of freedom, we infer the overlap of the produced many-body state with a W state from the observed Rabi oscillations and deduce the presence of entanglement. Finally, we investigate the breakdown of the superatom picture when two Rydberg excitations are present in the system, which leads to dephasing and a loss of coherence.
Engineering atomic wavepackets in very-high-n Rydberg atoms
NASA Astrophysics Data System (ADS)
Zhao, Wei
The remarkable level of control of atomic wavepackets that can be achieved using very-high-n Rydberg atoms (n ? 350) is demonstrated. This control is accomplished with carefully-tailored sequences of short unidirectional electric-field pulses, termed half-cycle pulses (HCPs), with duration Tp ? Tn, where Tn is the classical orbital period. In this limit, each HCP simply delivers an impulsive momentum transfer or "kick" to the Rydberg electron. We show that strongly polarized very-high-n (n 600) potassium Rydberg atoms can be produced by manipulating lower- n (n 350) polarized atoms. This enables us to study the response of such quasi-one-dimensional (quasi-1D) very-high- n Rydberg atoms to a periodic train of HCPs at high scaled frequencies, nu 0 > 15. Pronounced non-monotonic structure in the survival probability is observed as N, the number of HCPs in the train, is increased. This behavior is very sensitive to the polarization of the Rydberg states. A different protocol that enables us to localize and to steer Rydberg wavepackets in phase space is explained using classical phase-space portraits and confirmed experimentally by navigating phase-space localized wavepackets to targeted positions. Very-high-n quasi-1D Rydberg atoms also provide a valuable laboratory for studying irreversible dephasing, i.e., decoherence. This is demonstrated by observing the evolution of a Stark wavepacket containing states of different n in an external electric field. Based on a quantum beat echo technique we report the first demonstration of the reversibility of the dephasing of an ensemble of electric dipoles which is monitored by a probe HCP. This technique allows the measurement of decoherence in the presence of strong dephasing, which can be very important for quantum information processing. All experimental results are explained with the aid of classical trajectory Monte-Carlo simulations (CTMC) and good agreement is seen.
Simplified scheme for entanglement preparation with Rydberg pumping via dissipation
Shi-Lei Su; Qi Guo; Hong-Fu Wang; Shou Zhang
2015-07-26
Inspired by recent work [A. W. Carr and M. Saffman, Phys. Rev. Lett. 111, 033607 (2013)], 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 less 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, 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.
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.
Phase-Imprinting of Bose-Einstein Condensates with Rydberg Impurities
NASA Astrophysics Data System (ADS)
Mukherjee, Rick; Ates, Cenap; Li, Weibin; Wüster, Sebastian
2015-07-01
We show how the phase profile of Bose-Einstein condensates can be engineered through its interaction with localized Rydberg excitations. The interaction is made controllable and long range by off-resonantly coupling the condensate to another Rydberg state with laser light. Our technique allows the mapping of entanglement generated in systems of few strongly interacting Rydberg atoms onto much larger atom clouds in hybrid setups. As an example we discuss the creation of a spatial mesoscopic superposition state from a bright soliton. Additionally, the phase imprinted onto the condensate using the Rydberg excitations is a diagnostic tool for the latter. For example, a condensate time-of-flight image would permit reconstructing the pattern of an embedded Rydberg crystal.
Phase-Imprinting of Bose-Einstein Condensates with Rydberg Impurities.
Mukherjee, Rick; Ates, Cenap; Li, Weibin; Wüster, Sebastian
2015-07-24
We show how the phase profile of Bose-Einstein condensates can be engineered through its interaction with localized Rydberg excitations. The interaction is made controllable and long range by off-resonantly coupling the condensate to another Rydberg state with laser light. Our technique allows the mapping of entanglement generated in systems of few strongly interacting Rydberg atoms onto much larger atom clouds in hybrid setups. As an example we discuss the creation of a spatial mesoscopic superposition state from a bright soliton. Additionally, the phase imprinted onto the condensate using the Rydberg excitations is a diagnostic tool for the latter. For example, a condensate time-of-flight image would permit reconstructing the pattern of an embedded Rydberg crystal. PMID:26252669
Phase-Imprinting of Bose-Einstein Condensates with Rydberg Impurities
Mukherjee, Rick; Li, Weibin; Wüster, Sebastian
2015-01-01
We show how the phase profile of Bose-Einstein condensates can be engineered through its interaction with localized Rydberg excitations. The interaction is made controllable and long-range by off-resonantly coupling the condensate to another Rydberg state. Our technique allows the mapping of entanglement generated in systems of few strongly interacting Rydberg atoms onto much larger atom clouds in hybrid setups. As an example we discuss the creation of a spatial mesoscopic superposition state from a bright soliton. Additionally, the phase imprinted onto the condensate using the Rydberg excitations is a diagnostic tool for the latter. For example a condensate time-of-flight image would allow the reconstruction of an embedded Rydberg crystal pattern.
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.
Collisional dissociative recombination in helium-hydrogen afterglow plasmas
NASA Astrophysics Data System (ADS)
Johnsen, Rainer
2012-10-01
The puzzling dependence of electron-ion recombination in helium-hydrogen afterglows on neutralfootnotetextGlos'ik et al., Phys. Rev.A 79, 052707 (2009) and electronfootnotetextGougousi et al., Int. J. Mass Spec. Ion Proc. 149-150, 131 (1995) densities is shown to be compatible with the ``Collisional Dissociative Recombination'' mechanism, originally proposed by Collins,footnotetextCollins, Phys. Rev.A 140, 1850 (1965) in which three-body capture of electrons into molecular high Rydberg states of H3^+ leads to predissociation of the molecular core. While both electrons and neutrals play a role in the three-body capture, their effects on recombination do not add in a simple manner, which makes it difficult to distinguish three-body and binary dissociative recombination. Collision-induced angular momentum mixing (l-mixing), invoked in earlier models, also occurs but does not provide the rate-limiting step that controls the overall recombination rate.
Nephtali Garrido; Hector H. Hernandez
2012-01-19
We put to the test an effective three-dimensional electrostatic potential, obtained effectively by considering an electrostatic source inside a (5+$p$)-dimensional braneworld scenario with $p$ compact and one infinite spacial extra dimensions in the RS II-$p$ model, for $p=1$ and $p=2$. This potential is regular at the source and matches the standard Coulomb potential outside a neighborhood. We use variational and perturbative approximation methods to calculate corrections to the ground energy of the Helium atom modified by this potential, by making use of a 6 and 39-parameter trial wave function of Hylleraas type for the ground state. These corrections to the ground-state energy are compared with experimental data for Helium atom in order to set bounds for the extra dimensions length scale. We find that these bounds are less restrictive than the ones obtained by Morales et. al. through a calculation using the Lamb shift in Hydrogen.
Mather, William H.; Fox, Ronald F.
2006-10-15
Universal behavior of Gaussian-Klauder states emerges near soft classical turning points, as expressed through a complex-valued Airy transformation that approximates the wave function. Study of these classical turning points provides analytic evidence that Gaussian-Klauder states generally display recurrent localization for many classical orbital periods. Analytic position and momentum moments of the wave function are determined from this approximation, leading in part to connections with the traditionally chosen positional Gaussian wave functions as the limit of large energy uncertainty. Application of this procedure to hydrogenic states of maximal eccentricity leads to the classical limit of recurrent collisional bouncing in the Kepler problem, via the explicit construction of states that maintain phase space localization for many orbital periods.
Rydberg excitation of a Bose-Einstein condensate
Viteau, M; Radogostowicz, J; Malossi, N; Morsch, O; Ciampini, D; Arimondo, E
2012-01-01
We have performed two-photon excitation via the 6P3/2 state to n=50-80 S or D Rydberg state in Bose-Einstein condensates of rubidium atoms. The Rydberg excitation was performed in a quartz cell, where electric fields generated by plates external to the cell created electric charges on the cell walls. Avoiding accumulation of the charges and realizing good control over the applied electric field was obtained when the fields were applied only for a short time, typically a few microseconds. Rydberg excitations of the Bose-Einstein condensates loaded into quasi one-dimensional traps and in optical lattices have been investigated. The results for condensates expanded to different sizes in the one-dimensional trap agree well with the intuitive picture of a chain of Rydberg excitations controlled by the dipole-dipole interaction. The optical lattice applied along the one-dimensional geometry produces localized, collective Rydberg excitations controlled by the nearest-neighbour blockade.
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.
Giant Rydberg excitons in the copper oxide Cu2O.
Kazimierczuk, T; Fröhlich, D; Scheel, S; Stolz, H; Bayer, M
2014-10-16
A highly excited atom having an electron that has moved into a level with large principal quantum number is a hydrogen-like object, termed a Rydberg atom. The giant size of Rydberg atoms leads to huge interaction effects. Monitoring these interactions has provided insights into atomic and molecular physics on the single-quantum level. Excitons--the fundamental optical excitations in semiconductors, consisting of an electron and a positively charged hole--are the condensed-matter analogues of hydrogen. Highly excited excitons with extensions similar to those of Rydberg atoms are of interest because they can be placed and moved in a crystal with high precision using microscopic energy potential landscapes. The interaction of such Rydberg excitons may allow the formation of ordered exciton phases or the sensing of elementary excitations in their surroundings on a quantum level. Here we demonstrate the existence of Rydberg excitons in the copper oxide Cu2O, with principal quantum numbers as large as n = 25. These states have giant wavefunction extensions (that is, the average distance between the electron and the hole) of more than two micrometres, compared to about a nanometre for the ground state. The strong dipole-dipole interaction between such excitons is indicated by a blockade effect in which the presence of one exciton prevents the excitation of another in its vicinity. PMID:25318523
Hanni, M. E.; Keele, Julie A.; Lundeen, S. R.; Fehrenbach, C. W.; Sturrus, W. G. [Department of Physics, Colorado State University, Fort Collins, Colorado 80523 (United States); J. R. Macdonald Laboratory, Kansas State University, Manhattan, Kansas 66506 (United States); Department of Physics, Youngstown State University, Youngstown, Ohio 44555 (United States)
2010-04-15
The binding energies of high-L Rydberg levels of Pb{sup +} with n=19 or 20 and 6{<=}L{<=}10 were measured with resonant excitation Stark ionization spectroscopy (RESIS). When combined with previous measurements of members of the nh Rydberg series in Pb{sup +}, and analyzed with the long-range polarization model, these determined the polarizability of the 5d{sup 10}6s{sup 2} ground state of Pb{sup 2+} to be {alpha}{sub d} = 13.62(8) a.u. This value is substantially larger than the estimate published recently based on the measured lifetime of the 6s6p{sup 1}P{sub 1} resonance level of Pb{sup 2+}, 7.9(6) a.u. The difference is mostly due to the polarizability of Pb{sup 4+}, the 5d{sup 10} core of the Pb{sup 2+} ion. This was established by observation of resolved fine structure in the excitation of n=39, high-L Rydberg levels of Pb{sup 3+}, using the same RESIS technique. Analysis of this spectra determined the polarizability of Pb{sup 4+} to be {alpha}{sub d} = 3.61(4) a.u. Reanalysis of optical spectra of nh and ng levels in Pb{sup +} and Pb{sup 3+} in view of the polarizabilities determined in the RESIS studies indicates revised ionization energies of both ions, E{sub I}(Pb{sup +}) = 121245.28(6) cm{sup -1} and E{sub I}(Pb{sup 3+}) = 341 435.1(8) cm{sup -1}.
Janne Rydberg his life and work
NASA Astrophysics Data System (ADS)
Martinson, I.; Curtis, L. J.
2005-07-01
The Rydberg formula is emblematic of atomic spectroscopy. We review here the personal background, research accomplishments, and academic career of its discoverer, Janne Rydberg. Although his formula is often introduced as a generalization of the hydrogenic Balmer formula, Rydberg's work was independent of Balmer's, and displayed great ingenuity and a rare ability to recognize hidden patterns in complex numerical data. Although his discoveries attracted wide attention, experimental physics was then considered inseparable from measurement, and the fact that Rydberg's insightful formulations used the data of others impeded his academic career. Although Rydberg did not live to see the full theoretical implications of his discoveries, the vigorous study of Rydberg atoms continues today.
Rydberg excitation of Bose-Einstein condensates
Rolf Heidemann; Ulrich Raitzsch; Vera Bendkowsky; Björn Butscher; Robert Löw; Tilman Pfau
2007-10-30
Rydberg atoms provide a wide range of possibilities to tailor interactions in a quantum gas. Here we report on Rydberg excitation of Bose-Einstein condensed 87Rb atoms. The Rydberg fraction was investigated for various excitation times and temperatures above and below the condensation temperature. The excitation is locally blocked by the van der Waals interaction between Rydberg atoms to a density-dependent limit. Therefore the abrupt change of the thermal atomic density distribution to the characteristic bimodal distribution upon condensation could be observed in the Rydberg fraction. The observed features are reproduced by a simulation based on local collective Rydberg excitations.
Pulsed laser deposition of ZnO: Energetic Rydberg state atoms and their impact on film growth
Leuchtner, R.E. [Univ. of New Hampshire, Durham, NH (United States). Physics Dept.
1996-12-31
Zinc oxide films were grown on both <100>-MgO and amorphous SiO{sub 2} substrates using either a Zn or a ZnO target in a background ambient of oxygen. Using a time-of-flight quadrupole mass spectrometer (TOFQMS), the kinetic energies ({approximately}1--2,000 eV) and the charge state of atoms and small molecules in the ablation plumes from both targets were examined. A unique capability of this TOFQMS is the ability to examine the dynamics of the ion-electron recombination process, and this feature was used to try to quantify long-lived excited state particles within the ablation plume. It was found that the relative amount of neutral species formed by ion recombination was larger in the case of the Zn target compared to the ZnO. A detailed comparison of the ZnO film microstructure prepared with both targets at two deposition pressures (0.01 and 0.1 torr) and a variety of substrate temperatures from 50--500 C was performed. The crystallographic and morphological results suggest that the condensation of highly electronically excited state particles, both ions and long-lived excited state neutrals likely affects film growth, and can enhance desirable surface processes, such as athermal recrystallization and surface mobility, that favor oriented crystal growth at lower substrate temperatures.
Optical imaging of Rydberg atoms
Mazurenko, Anton
2012-01-01
We present an experiment exploring electromagnetically induced transparency (EIT) in Rydberg atoms in order to observe optical nonlinearities at the single photon level. ??Rb atoms are trapped and cooled using a magneto-optical ...
Photon-Photon Interactions via Rydberg Blockade
Alexey V. Gorshkov; Johannes Otterbach; Michael Fleischhauer; Thomas Pohl; Mikhail D. Lukin
2011-03-18
We develop the theory of light propagation under the conditions of electromagnetically induced transparency (EIT) in systems involving strongly interacting Rydberg states. Taking into account the quantum nature and the spatial propagation of light, we analyze interactions involving few-photon pulses. We demonstrate that this system can be used for the generation of nonclassical states of light including trains of single photons with an avoided volume between them, for implementing photon-photon quantum gates, as well as for studying many-body phenomena with strongly correlated photons.
Manipulation of Rydberg atoms by terahertz pulses
NASA Astrophysics Data System (ADS)
Jia, G. R.; Liu, Y. F.; Yu, K.; Zhao, Y. J.
2011-11-01
In this paper, ultrashort, unipolar electric-field (terahertz) pulses have been used to coherently control population transfer between Rydberg states in lithium atom. Our numerical results show that populations of lithium atoms can be driven to lower or higher n levels with a train of half-cycle pulses, and the the transition rate is sensitive to the static-electric-field strength, the main laser frequency, the optical pulse profile, and the chirp of the laser pulse. If the paramerters of the half-cycle pulses is optimized appropriately, the population can be transferred to the target state completely.
The effects of light-shift and temporal evolution on collective Rydberg excitations
NASA Astrophysics Data System (ADS)
Thaicharoen, Nithiwadee; Schwarzkopf, Andrew; Anderson, David; Raithel, Georg
2014-05-01
Optical dipole traps are widely used to trap and manipulate cold ground-state and Rydberg atoms. Here, we present a first study of the effects of dipole-trap-induced light shifts on the spatial pair-correlation function of Rydberg excitations generated in clouds of cold 85Rb atoms. We use ion imaging techniques to obtain the Rydberg pair-correlation functions. We measure and interpret the effects of excitation-laser detuning and dipole-trap-induced light shifts on the Rydberg excitation blockade. We also observe an enhancement of the probability of exciting two Rydberg atoms at a particular separation, which we explain as direct two-photon excitation of Rydberg-atom pairs. In a second experiment, we investigate the evolution of collective Rydberg excitations by adding a time delay between the excitation pulse and the read-out sequence. The observed time dependence of the pair-correlation signal reflects the van-der-Waals forces between the Rydberg atoms.
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 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. 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).
NASA Astrophysics Data System (ADS)
Liang, Liang; Wang, Y. C.
2003-11-01
The energy levels and lifetimes of 2s2ns 2S1/2 (n = 8-25) and 2s2nd 2D3/2 (n = 7-25) of neutral boron are calculated and predicted by means of multichannel quantum defect theory. The calculated lifetimes of 2s2ns 2S1/2 (n>11) characterized by the effective quantum number ngr are given by the formula tgrn = 0.0307ngr3 ns. In addition, the energy value of the core-excited state 2s2p3p 4P3/2 is assigned to 64 064.38 cm-1.
NASA Astrophysics Data System (ADS)
Closser, Kristina Danielle
This thesis presents new developments in excited state electronic structure theory. Contrasted with the ground state, the electronically excited states of atoms and molecules often are unstable and have short lifetimes, exhibit a greater diversity of character and are generally less well understood. The very unusual excited states of helium clusters motivated much of this work. These clusters consist of large numbers of atoms (experimentally 103--109 atoms) and bands of nearly degenerate excited states. For an isolated atom the lowest energy excitation energies are from 1s ? 2s and 1s ? 2 p transitions, and in clusters describing the lowest energy band minimally requires four states per atom. In the ground state the clusters are weakly bound by van der Waals interactions, however in the excited state they can form well-defined covalent bonds. The computational cost of quantum chemical calculations rapidly becomes prohibitive as the size of the systems increase. Standard excited-state methods such as configuration interaction singles (CIS) and time-dependent density functional theory (TD-DFT) can be used with ?100 atoms, and are optimized to treat only a few states. Thus, one of our primary aims is to develop a method which can treat these large systems with large numbers of nearly degenerate excited states. Additionally, excited states are generally formed far from their equilibrium structures. Vertical excitations from the ground state induce dynamics in the excited states. Thus, another focus of this work is to explore the results of these forces and the fate of the excited states. Very little was known about helium cluster excited states when this work began, thus we first investigated the excitations in small helium clusters consisting of 7 or 25 atoms using CIS. The character of these excited states was determined using attachment/detachment density analysis and we found that in the n = 2 manifold the excitations could generally be interpreted as superpositions of atomic states with surface states appearing close to the atomic excitation energies and interior states being blue shifted by up to ?2 eV. The dynamics resulting from excitation of He_7 were subsequently explored using ab initio molecular dynamics (AIMD). These simulations were performed with classical adiabatic dynamics coupled to a new state-following algorithm on CIS potential energy surfaces. Most clusters were found to completely dissociate and resulted in a single excited atomic state (90%), however, some trajectories formed bound, He*2 (3%), and a few yielded excited trimers (<0.5%). Comparisons were made with available experimental information on much larger clusters. Various applications of this state following algorithm are also presented. In addition to AIMD, these include excited-state geometry optimization and minimal energy path finding via the growing string method. When using state following we demonstrate that more physical results can be obtained with AIMD calculations. Also, the optimized geometries of three excited states of cytosine, two of which were not found without state following, and the minimal energy path between the lowest two singlet excited states of protonated formaldimine are offered as example applications. Finally, to address large clusters, a local variation of CIS was developed. This method exploits the properties of absolutely localized molecular orbitals (ALMOs) to limit the total number of excitations to scaling only linearly with cluster size, which results in formal scaling with the third power of the system size. The derivation of the equations and design of the algorithm are discussed in detail, and computational timings as well as a pilot application to the size dependence of the helium cluster spectrum are presented.
Slow-light polaritons in Rydberg gases
NASA Astrophysics Data System (ADS)
Fleischhauer, Michael
2012-02-01
Slow-light polaritons are quasi-particles generated in the interaction of photons with laser-driven atoms with a ?- or ladder-type coupling scheme under conditions of electromagnetically induced transparency (EIT). They are a superposition of electromagnetic and collective spin excitations. If one of the states making up the atomic spin is a high lying Rydberg level, the polaritons are subject to a strong and non-local interaction mediated by a dipole-dipole or van-der Waals coupling between excited Rydberg atoms. I will present and discuss an effective many-body model for these Rydberg polaritons. Depending on the detuning of the control laser the interaction potential between the polaritons can be repulsive or attractive and can have a large imaginary component for distances less than the so-called blockade radius. The non-local effective interaction gives rize to interesting many-body phenomena such as the generation of photons with an avoided volume, visible in stronlgy suppressed two-particle correlations inside the blockade volume. Moreover the long-range, power-law scaling of the interaction can in the repulsive case give rize to the formation of quasi-crystalline structures of photons. In a one dimensional system the low-energy dynamics of the polaritons can be described in terms of a Luttinger liquid. Using DMRG simulations the Luttinger K parameter is calculated and conditions for the formation of a quasi-crystal are derived. When confined to a two-dimensional geometry, e.g. using a resonator with quasi-degenerate transversal mode spectrum, Rydberg polaritons are an interesting candidate to study the bosonic fractional quantum Hall effect. I will argue that the formation of photons with an avoided volume is essential for explaining recent experiments on stationary EIT in Rydberg gases [1,2].[4pt] [1] J.D. Pritchard et al., Phys. Rev. Lett. 105, 193603 (2010). [0pt] [2] D. Petrosyan, J. Otterbach, and M. Fleischhauer, arXiv:1106.1360
Photoassociation of long-range nD Rydberg molecules
NASA Astrophysics Data System (ADS)
Raithel, Georg
2015-05-01
Cold atomic systems have opened new frontiers at the interface of atomic and molecular physics. Of particular interest are a recently discovered class of long-range, homonuclear Rydberg molecules first predicted in and observed in. In rubidium, these molecules are formed via low-energy electron scattering of the Rydberg electron from a 5S1/2 ground-state atom that is present within the Rydberg atom's volume. The binding mostly arises from S-wave and P-wave triplet scattering. In recent work, we have observed long-range homonuclear diatomic nD Rydberg molecules photoassociated out of an ultracold gas of 87Rb atoms for principal quantum numbers 34 <= n <= 40. Related results have also been reported in. The measured ground-state binding energies of 87Rb(nD + 5S1 / 2) molecular states are larger than those of their 87Rb(nS + 5S1 / 2) counterparts, showing the dependence of the molecular bond on the angular momentum of the Rydberg atom. We have exhibited the transition of 87Rb(nD + 5S1 / 2) molecules from a molecular-binding-dominant regime at low n to a fine-structure-dominant regime at high n [akin to Hund's cases (a) and (c), respectively]. In our analysis, we use a Fermi model that includes S-wave and P-wave singlet and triplet scattering, the fine structure coupling of the Rydberg atom and the hyperfine structure coupling of the 5S1/2 atom. The hyperfine structure is important because it gives rise to mixed singlet-triplet potentials. This work was supported by the AFOSR (FA9550-10-1-0453) and the NSF (PHY-1205559).
NASA Astrophysics Data System (ADS)
Atkins, K. R.
2014-06-01
Preface; 1. Introduction; 2. Equilibrium properties; 3. Theories; 4. The new thermodynamics; 5. First and second sound; 6. Further aspects of the thermodynamics; 7. Helium films; 8. Helium three; 9. He3-He4 mixtures; References; Index.
Mikhailov, A. I.; Nefiodov, A. V.
2011-02-15
The single-photon ionization of the ground state of a helium-like multicharged ion, which is accompanied by a simultaneous excitation of the residual ion to the np states, is studied using nonrelativistic pertubation theory with respect to the electron-electron interaction. Formulas describing the cross section for the process being studied are obtained. These formulas exhibit a scaling behavior in the target-nucleus charge number Z and in the principal quantum number n. Numerical calculations are performed for nonrelativistic energies including the near-threshold region.
Entanglement of neutral-atom chains by spin-exchange Rydberg interaction
NASA Astrophysics Data System (ADS)
Shi, Xiao-Feng; Bariani, F.; Kennedy, T. A. B.
2014-12-01
Conditions to achieve an unusually strong Rydberg spin-exchange interaction are investigated and proposed as a means to generate pairwise entanglement and realize a swap-like quantum gate for neutral atoms. Ground-state entanglement is created by mapping entangled Rydberg states to ground states using optical techniques. A protocol involving swap-gate and pairwise entanglement operations is predicted to create global entanglement of a chain of N atoms in a time that is independent of N .
Entanglement of neutral-atom chains by spin-exchange Rydberg interaction
Xiao-Feng Shi; F. Bariani; T. A. B. Kennedy
2014-12-09
Conditions to achieve an unusually strong Rydberg spin-exchange interaction are investigated and proposed as a means to generate pairwise entanglement and realize a SWAP-like quantum gate for neutral atoms. Ground-state entanglement is created by mapping entangled Rydberg states to ground states using optical techniques. A protocol involving SWAP gate and pairwise entanglement operations is predicted to create global entanglement of a chain of $N$ atoms in a time that is independent of $N$.
Formation of Antihydrogen Rydberg atoms in strong magnetic field traps
Pohl, T.; Sadeghpour, H. R. [ITAMP, Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge MA 02138 (United States)
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.
Strongly coupled plasmas via Rydberg blockade of cold atoms.
Bannasch, G; Killian, T C; Pohl, T
2013-06-21
We propose and analyze a new scheme to produce ultracold neutral plasmas deep in the strongly coupled regime. The method exploits the interaction blockade between cold atoms excited to high-lying Rydberg states and therefore does not require substantial extensions of current ultracold plasma experiments. Extensive simulations reveal a universal behavior of the resulting Coulomb coupling parameter, providing a direct connection between the physics of strongly correlated Rydberg gases and ultracold plasmas. The approach is shown to reduce currently accessible temperatures by more than an order of magnitude, which opens up a new regime for ultracold plasma research and cold ion-beam applications with readily available experimental techniques. PMID:23829735
Electrometry near a dielectric surface using Rydberg electromagnetically induced transparency
Abel, R. P.; Carr, C.; Krohn, U.; Adams, C. S. [Department of Physics, Durham University, Durham DH1 3LE (United Kingdom)
2011-08-15
Electrometry near a dielectric surface is performed using Rydberg electromagnetically induced transparency. The large polarizability of high-n-state Rydberg atoms gives this method extreme sensitivity. We show that dipoles produced by adsorbates on the dielectric surface produce a significant electric field that responds to an applied field with a time constant of order 1 s. For transient applied fields (with a time scale of less than 1 s) we observe good agreement with calculations based on numerical solutions of Laplace's equation using an effective dielectric constant to simulate the bulk dielectric.
Rotational autoionization of np Rydberg series of D2
NASA Astrophysics Data System (ADS)
Pratt, S. T.; Dehmer, P. M.; Dehmer, J. L.
1990-01-01
The rotational autoionization of the np Rydberg states of D2 was studied near the first ionization threshold using optical-optical double resonance techniques and photoelectron spectroscopy. The spectra obtained are found to be similar in many respects to those of H2 recorded by O'Halloran et al. (1989). In particular, a number of Rydberg series were observed to decay by processes other than the conventional singlet rotational autoionization mechanism. The D2 spectra have also been extended into longer wavelength regions and show additional nominally forbidden decay processes that were not observed in H2.
Collective Many-Body Interaction in Rydberg Dressed Atoms
Honer, Jens; Weimer, Hendrik; Buechler, Hans Peter; Pfau, Tilman
2010-10-15
We present a method to control the shape and character of the interaction potential between cold atomic gases by weakly dressing the atomic ground state with a Rydberg level. For increasing particle densities, a crossover takes place from a two-particle interaction into a collective many-body interaction, where the dipole-dipole or van der Waals blockade phenomenon between the Rydberg levels plays a dominant role. We study the influence of these collective interaction potentials on a Bose-Einstein condensate and present the optimal parameters for its experimental detection.
Rydberg-Rydberg interaction profile from the excitation dynamics of ultracold atoms in lattices
Mayle, Michael; Tezak, Nikolas; Schmelcher, Peter
2011-01-01
We propose a method for the determination of the interaction potential of Rydberg atoms. Specifically, we consider a laser-driven Rydberg gas confined in a one-dimensional lattice and demonstrate that the Rydberg atom number after a laser excitation cycle as a function of the laser detuning provides a measure for the Rydberg interaction coefficient. Resolving the spatial distribution of the excited Rydberg atoms additionally allows the determination of the scaling exponent of the interaction potential.
Quantum Spin-Ice and Dimer Models with Rydberg Atoms
NASA Astrophysics Data System (ADS)
Glaetzle, A. W.; Dalmonte, M.; Nath, R.; Rousochatzakis, I.; Moessner, R.; Zoller, P.
2014-10-01
Quantum spin-ice represents a paradigmatic example of how the physics of frustrated magnets is related to gauge theories. In the present work, we address the problem of approximately realizing quantum spin ice in two dimensions with cold atoms in optical lattices. The relevant interactions are obtained by weakly laser-admixing Rydberg states to the atomic ground-states, exploiting the strong angular dependence of van der Waals interactions between Rydberg p states together with the possibility of designing steplike potentials. This allows us to implement Abelian gauge theories in a series of geometries, which could be demonstrated within state-of-the-art atomic Rydberg experiments. We numerically analyze the family of resulting microscopic Hamiltonians and find that they exhibit both classical and quantum order by disorder, the latter yielding a quantum plaquette valence bond solid. We also present strategies to implement Abelian gauge theories using both s - and p -Rydberg states in exotic geometries, e.g., on a 4-8 lattice.
Binding potentials and interaction gates between microwave-dressed Rydberg atoms
David Petrosyan; Klaus Mřlmer
2014-09-22
We demonstrate finite range binding potentials between pairs of Rydberg atoms interacting with each other via attractive and repulsive van der Waals potentials and driven by a microwave field. We show that, using destructive quantum interference to cancel single-atom Rydberg excitation, the Rydberg-dimer states can be selectively and coherently populated from the two-atom ground state. This can be used to realize a two-qubit interaction gate which is not susceptible to mechanical forces between the atoms and is therefore immune to motional decoherence.
Divalent Rydberg atoms in optical lattices: Intensity landscape and magic trapping
NASA Astrophysics Data System (ADS)
Topcu, Turker; Derevianko, Andrei
2014-02-01
We develop a theoretical understanding of the trapping of divalent Rydberg atoms in optical lattices. Because the size of the Rydberg electron cloud can be comparable to the scale of spatial variations of laser intensity, we pay special attention to averaging optical fields over the atomic wave functions. The optical potential is proportional to the ac Stark polarizability. We find that in the independent-particle approximation for the valence electrons, this polarizability breaks into two contributions: the singly ionized core polarizability and the contribution from the Rydberg electron. Unlike the usually employed free-electron polarizability, the Rydberg contribution depends both on the laser intensity profile and on the rotational symmetry of the total electronic wave function. We focus on the J =0 Rydberg states of Sr and evaluate the dynamic polarizabilities of the 5sns(1S0) and 5snp(3P0) Rydberg states. We specifically chose the Sr atom for its optical-lattice clock applications. We find that there are several magic wavelengths in the infrared region of the spectrum at which the differential Stark shift between the clock states [5s2(1S0) and 5s5p(3P0)] and the J =0 Rydberg states [5sns(1S0) and 5snp(3P0)] vanishes. We tabulate these wavelengths as a function of the principal quantum number n of the Rydberg electron. We find that because the contribution to the total polarizability from the Rydberg electron vanishes at short wavelengths, magic wavelengths below 1000 nm are "universal" as they do not depend on the principal quantum number n.
Entangled optical clocks via Rydberg blockade
NASA Astrophysics Data System (ADS)
Komar, Peter; Kessler, Eric; Topcu, Turker; Derevianko, Andrei; Lukin, Mikhail
2015-05-01
We present an analysis of a protocol for creating fully entangled GHZ-type states of atoms in spatially separated optical atomic clocks. In our scheme, local operations make use of the strong dipole-dipole interaction between Rydberg excitations, which give rise to fast and reliable quantum operations involving all atoms in the ensemble. The necessary entanglement between distant ensembles is mediated by single-photon quantum channels and collectively enhanced light-matter couplings. These techniques can be used to create the recently proposed quantum clock network based on neutral atom optical clocks. We specifically analyze the realization of this scheme based on neutral Yb atoms.
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 (?He+) is a three-body atom composed of a helium nucleus, an electron occupying the 1s ground state, and a negatively charged pion ?- in a Rydberg state with principal and orbital angular momentum quantum numbers of n ?+116. We calculate the spin-independent energies of the ?3He+ and ?4He+ isotopes in the region n =15-19. These include relativistic and quantum electrodynamics corrections of orders R??2 and R??3 in atomic units, where R? and ? denote the Rydberg and fine structure constants. The fine-structure splitting due to the coupling between the electron spin and the orbital angular momentum of the ?- and the radiative and Auger decay rates of the states are also calculated. Some states (n,?)=(16,15) and (17,16) retain nanosecond-scale lifetimes against ?- absorption into the helium nucleus. We propose the use of laser pulses to induce ?- transitions from these metastable states to states with large (1011 s-1) Auger rates. The ?He2+ ion that remains after Auger emission of the 1s electron undergoes Stark mixing with the s, p, and d states during collisions with the helium atoms in the experimental target. This leads to immediate nuclear absorption of the ? -. The resonance condition between the laser beam and the atom is thus revealed as a sharp spike in the rates of neutrons, protons, deuterons, and tritons that emerge. A resonance curve is obtained from which the ?He+ transition frequency can in principle be determined with a fractional precision of 10-8-10-6 provided the systematic uncertainties can be controlled. By comparing the measured ?He+ frequencies with the calculated values, the ?- mass may be determined with a similar precision. The ?He+ will be synthesized by allowing a high-intensity (>108 s-1) beam of ?-produced by a cyclotron to come to rest in a helium target. The precise time structure of the ?- beam is used to ensure a sufficient rate of coincidence between the resonant laser pulses and the ?He+ atoms.
Single atom Rydberg excitation in a small dipole trap.
Zuo, Zhanchun; Fukusen, Miho; Tamaki, Yoshihito; Watanabe, Tomoki; Nakagawa, Yusuke; Nakagawa, Ken'ichi
2009-12-01
We have realized a single atom trap using a magneto-optical trap (MOT) with a high magnetic field gradient and a small optical dipole trap. Using this trap, we demonstrate the excitation to a highly excited Rydberg state (n=43) with a single Rubidium atom. PMID:20052216
Experimental Determination of the Lifetime for the 2p3d(1P0) Helium Doubly Excited State
NASA Astrophysics Data System (ADS)
Lambourne, J. G.; Penent, F.; Lablanquie, P.; Hall, R. I.; Ahmad, M.; itnik, M.; Bu?ar, K.; Odling-Smee, M. K.; Harries, J. R.; Hammond, P.; Waterhouse, D. K.; Stranges, S.; Richter, R.; Alagia, M.; Coreno, M.; Ferianis, M.
2003-04-01
Two recent theoretical studies [
Stavros, Vasilios G; Lau, Lana; Strasser, Daniel; Leone, Stephen R
2006-05-01
A two-state vibrational wave packet is prepared in a low-lying 4d[12](1 or 2) Rydberg state of jet cooled Br(2) (4d, v(')=3 and v(')=4) by two-photon excitation with 266.5 nm pulses from an ultrafast laser. The wave packet is detected by autoionization following excitation with time-delayed 800 nm pulses to the n=8 (v(+)=4) and n=9 (v(+)=3) Rydberg states in the (2)Pi(12) angular momentum core state. Autoionization of each state occurs to the (2)Pi(32) state of the ion through spin-orbit ionization. Photoelectron spectroscopy is used to differentiate between the n=8 and n=9 ejected photoelectrons. Detection of the wave packet recurrences via the n=8 and n=9 Rydberg states reveals a pi phase-shift difference of the recurrences between the two final states. In each case, Delta v not equal 0 transitions are observed since wave packet recurrences are detected. By fitting the observed phase change of the recurrences with a simple model for the overlap amplitudes and assumptions about the potentials, we estimate, within the context of the model, that approximately 0.6% of the transitions may be attributed to Delta v= +/- 1 transitions between the initial Rydberg superposition state and the final Rydberg detection state. PMID:16689571
Quantum Interference in Field Ionization of Rydberg Atoms
NASA Astrophysics Data System (ADS)
Feynman, Rachel; Hollingsworth, Jacob; Vennittilli, Michael; Budner, Tamas; Zmiewski, Ryan; Fahey, Donald P.; Carroll, Thomas J.; Noel, Michael W.
2015-05-01
We excite ultracold rubidium atoms in a magneto-optical trap to a coherent superposition of three | mj | sublevels of a Rydberg state. After a delay in which the relative phase of the states evolve, we field ionize the atoms. The process of ionization is complicated by the details of the state structure for a weakly bound electron in Rydberg states. As these states ionize, their ionization pathways overlap, allowing them to interfere. We find that the result of this interference is dependent on the relative phase between the three states, and that the phase evolves in time inversely with the energy separation between the states. This material is based upon work supported by the National Science Foundation under Grant No. 1205897.
On highly accurate calculations of the excited $n^1S(L = 0)-$states in helium atoms
Alexei M. Frolov; David M. Wardlaw
2011-02-25
The total energies and various bound state properties of the excited $2^1S(L = 0)-$states in two-electron helium atoms, including the ${}^{\\infty}$He, ${}^4$He and ${}^3$He atoms, are determined to very high numerical accuracy. The convergence of the results obtained for some electron-nuclear and electron-electron expectation values and, in particular, for the electron-nuclear and electron-electron cusp values, is discussed. The field component of the isotope shift and lowest order QED correction are estimated for the $2^1S(L = 0)-$states in the ${}^4$He and ${}^3$He atoms. We also apply our highly accurate methods to numerical computations of the excited $n^1S-$states (for $n$ = 3 and 4) in two-electron atomic systems.
On Helium Anions in Helium Droplets: Interpreting Recent Experiments
NASA Astrophysics Data System (ADS)
Mauracher, Andreas; Huber, Stefan E.
2014-10-01
Helium droplets provide an ideal environment to study elementary processes in atomic systems at very low temperatures. Here, we discuss properties of charged and neutral, atomic and molecular helium species formed in helium droplets upon electron impact. By studying their interaction with atomic ground state helium we find that He, He2 and excited (metastable) He*- are well bound within the helium droplet. In comparison, He* , He2* and He2* are found to be squeezed out due to energetic reasons. We also present the formation pathways of atomic and molecular helium anions in helium droplets. Transition barriers in the energetic lowest He*- - He interaction potentials prevent molecule formation at the extremely low temperatures in helium droplets. In contrast, some excited states allow a barrier-free formation of molecular helium (anions). With these theoretical results at hand we can interpret recent experiments in which the resonant formation of atomic and molecular helium anions was observed. Furthermore, we give an outlook on the implications of the presence of these anionic species in doped helium droplets with regard to charge transfer reactions. Austrian Fund Agency (FWF, I 978-N20, DK+ project Computational Interdisciplinary Modelling W1227-N16)/Austrian Ministry of Science (BMWF, Konjunkturpaket II, UniInfrastrukturprogramm of the Focal Point Scientific Computing).
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.
Rydberg spectroscopy of Fr-like thorium and uranium ions
NASA Astrophysics Data System (ADS)
Hanni, Mark Earl
The binding energies of high L Rydberg levels of Th 3+ were measured using the resonant excitation Stark ionization spectroscopy (RESIS) technique. When analyzed using the long range polarization model the measured energies determine the dipole and quadrupole polarizability of the Th4+ ion: alphad = 7.61(6) a.u. and alphaQ = 45(4) a.u. The RESIS technique and apparatus constructed for this study are discussed in this work. Modifications to the original design of the detector are presented. The modifications to the detector increased the energy resolution of the beams in the detector. It was determined that a significant source of background present in the observations of the U5+ Rydberg fine structure is due to the presence of auto-ionizing Rydberg states attached to metastable excited ion cores. These auto-ionizing states severely limit the fine structure observations, preventing the successful observation of any U5+ Rydberg fine structure.Also discussed are future directions that could lead to an increase in the signal to noise in the Th3+ fine structure observations and to a successful measurement of the dipole polarizability of U6+ .
Colgan, J.; Pindzola, M.S.
2003-01-01
We apply the time-dependent close-coupling method to the double photoionization of helium from its 1s2s {sup 1,3}S metastable states. Total integral cross sections are in excellent agreement with other nonperturbative theories. Single and triple differential cross sections are also presented which show interesting differences with previous calculations from the 1s{sup 2} ground state of helium. This set of calculations provides a goal for experimentalists to measure absolute total and angular differential cross sections for double ionization processes from excited states of atoms.
Fermionic Collective Excitations in a Lattice Gas of Rydberg Atoms
Olmos, B. [Instituto 'Carlos I' de Fisica Teorica y Computacional and Departamento de Fisica Atomica, Molecular y Nuclear, Universidad de Granada, E-18071 Granada (Spain); Midlands Ultracold Atom Research Centre-MUARC, The University of Nottingham, School of Physics and Astronomy, Nottingham (United Kingdom); Gonzalez-Ferez, R. [Instituto 'Carlos I' de Fisica Teorica y Computacional and Departamento de Fisica Atomica, Molecular y Nuclear, Universidad de Granada, E-18071 Granada (Spain); Lesanovsky, I. [Midlands Ultracold Atom Research Centre-MUARC, The University of Nottingham, School of Physics and Astronomy, Nottingham (United Kingdom)
2009-10-30
We investigate the many-body quantum states of a laser-driven gas of Rydberg atoms confined to a large spacing ring lattice. If the laser driving is much stronger than the van der Waals interaction among the Rydberg atoms, these many-body states are collective fermionic excitations. The first excited state is a spin wave that extends over the entire lattice. We demonstrate that our system permits us to study fermions in the presence of disorder although no external atomic motion takes place. We analyze how this disorder influences the excitation properties of the fermionic states. Our work shows a route towards the creation of complex many-particle states with atoms in lattices.
Quantum Magnetism and Topological Ordering via Rydberg Dressing near Förster Resonances.
van Bijnen, R M W; Pohl, T
2015-06-19
We devise a cold-atom approach to realizing a broad range of bilinear quantum magnets. Our scheme is based on off-resonant single-photon excitation of Rydberg P states (Rydberg dressing), whose strong interactions are shown to yield controllable XYZ interactions between effective spins, represented by different atomic ground states. The distinctive features of Förster-resonant Rydberg atom interactions are exploited to enhance the effectiveness of Rydberg dressing and, thereby, yield large spin interactions that greatly exceed the corresponding decoherence rates. We illustrate the concept on a spin-1 chain implemented with cold rubidium atoms, and demonstrate that this permits the dynamical preparation of topological magnetic phases. Generally, the described approach provides a viable route to exploring quantum magnetism with dynamically tunable (an)isotropic interactions as well as variable space and spin dimensions in cold-atom experiments. PMID:26196973
Spinorbit coupled BoseEinstein condensates with Rydberg-dressing interaction
NASA Astrophysics Data System (ADS)
Lü, Hao; Zhu, Shao-Bing; Qian, Jun; Wang, Yu-Zhu
2015-09-01
Interaction between Rydberg atoms can be used to control the properties of interatomic interaction in ultracold gases by weakly dressing the atoms with a Rydberg state. Here we investigate the effect of the Rydberg-dressing interaction on the ground-state properties of a BoseEinstein condensate imposed by Raman-induced spinorbit coupling. We find that, in the case of SU(2)-invariant s-wave interactions, the gas is only in the plane-wave phase and the zero-momentum phase is absent. In particular, we also predict an unexpected magnetic stripe phase composed of two plane-wave components with unequal weight when s-wave interactions are non-symmetric, which originates from the Rydberg-dressing interaction. Project supported by the National Basic Research Program of China (Grant No. 2011CB921504) and the National Natural Science Foundation of China (Grant No. 11104292).
Quantum Magnetism and Topological Ordering via Rydberg Dressing near Förster Resonances
NASA Astrophysics Data System (ADS)
van Bijnen, R. M. W.; Pohl, T.
2015-06-01
We devise a cold-atom approach to realizing a broad range of bilinear quantum magnets. Our scheme is based on off-resonant single-photon excitation of Rydberg P states (Rydberg dressing), whose strong interactions are shown to yield controllable X Y Z interactions between effective spins, represented by different atomic ground states. The distinctive features of Förster-resonant Rydberg atom interactions are exploited to enhance the effectiveness of Rydberg dressing and, thereby, yield large spin interactions that greatly exceed the corresponding decoherence rates. We illustrate the concept on a spin-1 chain implemented with cold rubidium atoms, and demonstrate that this permits the dynamical preparation of topological magnetic phases. Generally, the described approach provides a viable route to exploring quantum magnetism with dynamically tunable (an)isotropic interactions as well as variable space and spin dimensions in cold-atom experiments.
Tsogbayar, Ts; Korobov, V I
2006-07-14
Effective potentials of the relativistic Breit-Pauli corrections for the 1ssigma(g) and 2psigma(u) electron states of the H(2) (+) molecular ion and the 1ssigma, 2ssigma, and 3psigma states of the antiprotonic helium atom He(+)(-)p are calculated within the Born-Oppenheimer approximation. The variational expansion with randomly chosen exponents has been used for numerical studies. The results obtained for the Breit-Pauli effective potentials are accurate up to ten significant digits for the H(2) (+) molecular ion and eight digits for the He(+)(-)p atom. PMID:16848585
Direct observation of Rydberg-Rydberg transitions via CPmmW spectroscopy
Zhou, Yan, Ph. D. Massachusetts Institute of Technology
2014-01-01
Rydberg-Rydberg transitions of BaF molecules have been directly observed in our lab. The key to the experimental success is our ability to combine two powerful and new technologies, Chirped-Pulse millimeter-Wave spectroscopy ...
Lamb shift of electronic states in neutral muonic helium, an electron-muon-nucleus system
NASA Astrophysics Data System (ADS)
Karshenboim, Savely G.; Ivanov, Vladimir G.; Amusia, Miron
2015-03-01
Neutral muonic helium is an exotic atomic system consisting of an electron, a muon, and a nucleus. Being a three-body system, it possesses a clear hierarchy. This allows us to consider it as a hydrogenlike atom with a compound nucleus, which is, in turn, another hydrogenlike system. There are a number of corrections to the Bohr energy levels, all of which can be treated as contributions of generic hydrogenlike theory. While the form of those contributions is the same for all hydrogenlike atoms, their relative numerical importance differs from atom to atom. Here, the leading contribution to the (electronic) Lamb shift in neutral muonic helium is found in a closed analytic form together with the most important corrections. We believe that the Lamb shift in neutral muonic hydrogen is measurable, at least through a measurement of the (electronic) 1 s -2 s transition. We present a theoretical prediction for the 1 s -2 s transitions with an uncertainty of 3 ppm (9 GHz ), as well as for the 2 s -2 p Lamb shift with an uncertainty of 1.3 GHz .
Partial photoionization cross sections of NH4 and H3O Rydberg radicals.
Velasco, A M; Lavín, C; Martín, I; Melin, J; Ortiz, J V
2009-07-14
Photoionization cross sections for various Rydberg series that correspond to ionization channels of ammonium and oxonium Rydberg radicals from the outermost, occupied orbitals of their respective ground states are reported. These properties are known to be relevant in photoelectron dynamics studies. For the present calculations, the molecular-adapted quantum defect orbital method has been employed. A Cooper minimum has been found in the 3sa(1)-kpt(2) Rydberg channel of NH(4) beyond the ionization threshold, which provides the main contribution to the photoionization of this radical. However, no net minimum is found in the partial cross section of H(3)O despite the presence of minima in the 3sa(1)-kpe and 3sa(1)-kpa(1) Rydberg channels. The complete oscillator strength distributions spanning the discrete and continuous regions of both radicals exhibit the expected continuity across the ionization threshold. PMID:19603967
Rydberg excitation of neutral nitric oxide molecules in strong UV and near-IR laser fields
NASA Astrophysics Data System (ADS)
Lv, Hang; Zhang, Jun-Feng; Zuo, Wan-Long; Xu, Hai-Feng; Jin, Ming-Xing; Ding, Da-Jun
2015-06-01
Rydberg state excitations of neutral nitric oxide molecules are studied in strong ultraviolet (UV) and near-infra-red (IR) laser fields using a linear time-of-flight (TOF) mass spectrometer with the pulsed electronic field ionization method. The yield of Rydberg molecules is measured as a function of laser intensity and ellipticity, and the results in UV laser fields are compared with those in near-IR laser fields. The present study provides the first experimental evidence of neutral Rydberg molecules surviving in a strong laser field. The results indicate that a rescattering-after-tunneling process is the main contribution to the formation of Rydberg molecules in strong near-IR laser fields, while multi-photon excitation may play an important role in the strong UV laser fields. Project supported by the National Basic Research Program of China (Grant No. 2013CB922200) and the National Natural Science Foundation of China (Grant Nos. 11034003 and 11274140).
Abundances, charge states, and energy spectra of helium and heavy ions during solar particle events
NASA Technical Reports Server (NTRS)
Gloeckler, G.; Sciambi, R.; Fan, C. Y.; Hovestadt, D.
1975-01-01
Carbon and oxygen energy spectra observed during several solar events indicate a systematic deviation of these spectra from a simple power law: the spectra bend down below about 100 keV/nuc and the amount of this bending is highly correlated with the size of the flare, as measured by the 'event averaged' flux of 130-220 keV protons. The energy spectra of helium computed for the same time periods do not show a similar feature. A large variability of the alpha/CNO ratio is found from event to event (from 2 to about 20 at 40 keV/nuc), and in all cases examined the carbon and oxygen nuclei are nearly fully stripped. These results are interpreted as evidence for storage of energetic ions in hot coronal regions, followed by strong adiabatic deceleration.
Dynamical crystallization in a low-dimensional Rydberg gas
Schauß, Peter; Fukuhara, Takeshi; Hild, Sebastian; Cheneau, Marc; Macrě, Tommaso; Pohl, Thomas; Bloch, Immanuel; Gross, Christian
2014-01-01
Dominating finite-range interactions in many-body systems can lead to intriguing self-ordered phases of matter. Well known examples are crystalline solids or Coulomb crystals in ion traps. In those systems, crystallization proceeds via a classical transition, driven by thermal fluctuations. In contrast, ensembles of ultracold atoms laser-excited to Rydberg states provide a well-controlled quantum system, in which a crystalline phase transition governed by quantum fluctuations can be explored. Here we report on the experimental preparation of the crystalline states in such a Rydberg many-body system. Fast coherent control on the many-body level is achieved via numerically optimized laser excitation pulses. We observe an excitation-number staircase as a function of the system size and show directly the emergence of incompressible ordered states on its steps. Our results demonstrate the applicability of quantum optical control techniques in strongly interacting systems, paving the way towards the investigation o...
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. 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.
Population transfer in the Na s-p Rydberg ladder by a chirped microwave pulse
Maeda, H.; Gurian, J. H.; Gallagher, T. F.
2011-12-15
While quantum defects of nl Rydberg states of Na with l{>=}2 are nearly equal to zero, the quantum defects of ns and np states of Na are quite large due to the finite size of its ionic core. Since the Na ns and np states are energetically isolated from the higher angular momentum states of the same n, we can think of the Na ns and np Rydberg states as a specific example of a simple multilevel ladder system consisting of only alternating s and p angular momentum states. Here we report that population transfer in the Na s-p Rydberg ladder can be effectively achieved using a frequency-chirped microwave pulse, which couples only s and p states under suitable conditions.
Rydberg-Rydberg interaction profile from the excitation dynamics of ultracold atoms in lattices
Michael Mayle; Wolfgang Zeller; Nikolas Tezak; Peter Schmelcher
2011-08-01
We propose a method for the determination of the interaction potential of Rydberg atoms. Specifically, we consider a laser-driven Rydberg gas confined in a one-dimensional lattice and demonstrate that the Rydberg atom number after a laser excitation cycle as a function of the laser detuning provides a measure for the Rydberg interaction coefficient. With the lattice spacing precisely known, the proposed scheme only relies on the measurement of the number of Rydberg atoms and thus circumvents the necessity to map the interaction potential by varying the interparticle separation.
Rydberg-Rydberg interaction profile from the excitation dynamics of ultracold atoms in lattices
Mayle, Michael; Zeller, Wolfgang; Tezak, Nikolas; Schmelcher, Peter
2011-07-15
We propose a method for the determination of the interaction potential of Rydberg atoms. Specifically, we consider a laser-driven Rydberg gas confined in a one-dimensional lattice and demonstrate that the Rydberg atom number after a laser excitation cycle as a function of the laser detuning provides a measure for the Rydberg interaction coefficient. With the lattice spacing precisely known, the proposed scheme only relies on the measurement of the number of Rydberg atoms and thus circumvents the necessity to map the interaction potential by varying the interparticle separation.
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.
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.
NASA Astrophysics Data System (ADS)
Bacellar, C.; Ziemkiewicz, M. P.; Leone, S. R.; Neumark, D. M.; Gessner, O.
2015-05-01
Superfluid helium nanodroplets provide a unique cryogenic matrix for high resolution spectroscopy and ultracold chemistry applications. With increasing photon energy and, in particular, in the increasingly important Extreme Ultraviolet (EUV) regime, the droplets become optically dense and, therefore, participate in the EUV-induced dynamics. Energy- and charge-transfer mechanisms between the host droplets and dopant atoms, however, are poorly understood. Static energy domain measurements of helium droplets doped with noble gas atoms (Xe, Kr) indicate that Penning ionization due to energy transfer from the excited droplet to dopant atoms may be a significant relaxation channel. We have set up a femtosecond time-resolved photoelectron imaging experiment to probe these dynamics directly in the time-domain. Droplets containing 104 to 106 helium atoms and a small percentage (<10-4) of dopant atoms (Xe, Kr, Ne) are excited to the 1s2p Rydberg band by 21.6 eV photons produced by high harmonic generation (HHG). Transiently populated states are probed by 1.6 eV photons, generating time-dependent photoelectron kinetic energy distributions, which are monitored by velocity map imaging (VMI). The results will provide new information about the dynamic timescales and the different relaxation channels, giving access to a more complete physical picture of solvent-solute interactions in the superfluid environment. Prospects and challenges of the novel experiment as well as preliminary experimental results will be discussed.
Controlling ultracold chemical reactions via Rydberg-dressed interactions
Jia Wang; Jason N. Byrd; Ion Simbotin; R. Côté
2014-03-24
We show that ultracold chemical reactions can be manipulated and controlled by using Rydberg-dressed interactions. Scattering in the ultracold regime is sensitive to long-range interactions, especially when weakly bound (or quasi-bound) states exist near the collision threshold. We investigate how, by Rydberg-dressing a reactant, one enhances its polarizability and modifies the long-range van der Waals collision complex, which can alter chemical reaction rates by shifting the position of near threshold bound states. We carry out a full quantum mechanical scattering calculation for the benchmark system H$_2$+D, and show that resonances can be moved substantially and that rate coefficients at cold and ultracold temperatures can be increased by several orders of magnitude.
Robust quantum logic in neutral atoms via adiabatic Rydberg dressing
Tyler Keating; Robert L. Cook; Aaron Hankin; Yuan-Yu Jau; Grant W. Biedermann; Ivan H. Deutsch
2015-02-23
We study a scheme for implementing a controlled-Z (CZ) gate between two neutral-atom qubits based on the Rydberg blockade mechanism in a manner that is robust to errors caused by atomic motion. By employing adiabatic dressing of the ground electronic state, we can protect the gate from decoherence due to random phase errors that typically arise because of atomic thermal motion. In addition, the adiabatic protocol allows for a Doppler-free configuration that involves counterpropagating lasers in a $\\sigma_+/\\sigma_-$ orthogonal polarization geometry that further reduces motional errors due to Doppler shifts. The residual motional error is dominated by dipole-dipole forces acting on doubly-excited Rydberg atoms when the blockade is imperfect. For reasonable parameters, with qubits encoded into the clock states of $^{133}$Cs, we predict that our protocol could produce a CZ gate in $<10$ $\\mu$s with error probability on the order of $10^{-3}$.
Robust quantum logic in neutral atoms via adiabatic Rydberg dressing
NASA Astrophysics Data System (ADS)
Keating, Tyler; Cook, Robert L.; Hankin, Aaron M.; Jau, Yuan-Yu; Biedermann, Grant W.; Deutsch, Ivan H.
2015-01-01
We study a scheme for implementing a controlled-Z (cz) gate between two neutral-atom qubits based on the Rydberg blockade mechanism in a manner that is robust to errors caused by atomic motion. By employing adiabatic dressing of the ground electronic state, we can protect the gate from decoherence due to random phase errors that typically arise because of atomic thermal motion. In addition, the adiabatic protocol allows for a Doppler-free configuration that involves counterpropagating lasers in a ?+/?- orthogonal polarization geometry that further reduces motional errors due to Doppler shifts. The residual motional error is dominated by dipole-dipole forces acting on doubly excited Rydberg atoms when the blockade is imperfect. For reasonable parameters, with qubits encoded into the clock states of 133Cs, we predict that our protocol could produce a cz gate in <10 ? s with error probability on the order of 10-3.
Entropy and complexity analysis of hydrogenic Rydberg atoms
Lopez-Rosa, S. [Instituto Carlos I de Fisica Teorica y Computacional, Universidad de Granada, 18071-Granada (Spain) [Instituto Carlos I de Fisica Teorica y Computacional, Universidad de Granada, 18071-Granada (Spain); Departamento de Fisica Aplicada II, Universidad de Sevilla, 41012-Sevilla (Spain); Toranzo, I. V.; Dehesa, J. S. [Instituto Carlos I de Fisica Teorica y Computacional, Universidad de Granada, 18071-Granada (Spain) [Instituto Carlos I de Fisica Teorica y Computacional, Universidad de Granada, 18071-Granada (Spain); Departamento de Fisica Atomica, Molecular y Nuclear, Universidad de Granada, 18071-Granada (Spain); Sanchez-Moreno, P. [Instituto Carlos I de Fisica Teorica y Computacional, Universidad de Granada, 18071-Granada (Spain) [Instituto Carlos I de Fisica Teorica y Computacional, Universidad de Granada, 18071-Granada (Spain); Departamento de Matematica Aplicada, Universidad de Granada, 18071-Granada (Spain)
2013-05-15
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.
Dynamical entanglement and chaos: the case of Rydberg molecules
M Lombardi; A Matzkin
2006-06-08
A Rydberg molecule is composed of an outer electron that collides on the residual ionic core. Typical states of Rydberg molecules display entanglement between the outer electron and the core. In this work we quantify the average entanglement of molecular eigenstates and further investigate the time evolution of entanglement production from initially unentangled states. The results are contrasted with the underlying classical dynamics, obtained from the semiclassical limit of the core-electron collision. Our findings indicate that entanglement is not simply correlated with the degree of classical chaos, but rather depends on the specific phase-space features that give rise to inelastic scattering. Hence mixed phase-space or even regular classical dynamics can be associated with high entanglement generation.
On the Binary Helium Star DY Centauri: Chemical Composition and Evolutionary State
NASA Astrophysics Data System (ADS)
Pandey, Gajendra; Kameswara Rao, N.; Jeffery, C. Simon; Lambert, David L.
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.
On the binary helium star DY Centauri: chemical composition and evolutionary state
Pandey, Gajendra; Rao, N. Kameswara [Indian Institute of Astrophysics, Bangalore 560034 (India); Jeffery, C. Simon [Armagh Observatory, Collage Hill, Armagh BT61 9DG (United Kingdom); Lambert, David L., E-mail: pandey@iiap.res.in, E-mail: nkrao@iiap.res.in, E-mail: csj@arm.ac.uk, E-mail: dll@astro.as.utexas.edu [The W. J. McDonald Observatory and Department of Astronomy, University of Texas at Austin, Austin, TX 78712-1083 (United States)
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.
Lamb Shift Excitation Energy in the Ground State of the Helium Atom
E. E. Salpeter; M. H. Zaidi
1962-01-01
The evaluation of the Lamb shift excitation requires a knowledge of the oscillator strengths for transitions to all states which may be reached by dipole transitions from the ground state. The oscillator strengths for transitions to the continuum states (1s, ?p) and (2s, ?p) are calculated, using the 18-parameter ground-state wave function of Chandrasekhar and Herzberg. For the excited state
Photoinitiated collisions between cold Cs Rydberg atoms
Overstreet, K. Richard; Schwettmann, Arne; Tallant, Jonathan; Shaffer, James P. [University of Oklahoma, Homer L. Dodge Department of Physics and Astronomy, 440 West Brooks Street, Norman, Oklahoma 73019 (United States)
2007-07-15
Experimental studies of a photoinitiated collision in an ultracold Cs Rydberg gas are presented. The process is characterized by measuring the laser intensity dependence of the absorption, the number of particles leaving each collision, and the recoil velocity of the collision fragments. The results of the experiment are compared to ab initio Rydberg pair interaction potentials.
Quantum computing with cold atoms and Rydberg blockade
NASA Astrophysics Data System (ADS)
Saffman, Mark
2015-05-01
Optically trapped neutral atoms are one of several leading approaches to scalable quantum information processing. When prepared in electronic ground states in deep optical lattices atomic qubits are weakly interacting with long coherence times. Excitation to Rydberg states turns on strong interactions which enable fast gates and entanglement generation through either coherent evolution or dissipative dynamics. Rydberg interactions can be applied in a variety of ways enabling control of single atom qubits, multi-atom ensemble qubits, and hybrid entanglement between different types of atoms, between atoms and photons, or between atoms and solid state qubits. I will present advances that leverage strong Rydberg interactions for implementation of a small scale quantum computing device. We trap 30 or more atomic qubits in a 2D array of 49 sites. Single qubit gates are performed with fidelities better than 0.999 as characterized by random benchmarking. Two-qubit gates and entanglement are demonstrated between qubit pairs. Experimental gate fidelities are not yet sufficient for reliable error correction and scalable quantum computation. I will describe prospects for reaching the fault tolerance threshold based on new gate protocols with the potential for fast generation of entanglement at fidelities better than 0.9999. Work supported by the NSF, IARPA MQCO program, ARO, and AFOSR.
Angular-momentum couplings in long-range Rydberg molecules
NASA Astrophysics Data System (ADS)
Anderson, David; Miller, Stephanie; Raithel, Georg
2015-05-01
We present results of a recent theoretical study of angular-momentum couplings in long-range diatomic Rydberg molecules formed between a rubidium Rydberg and 5S1 / 2 ground-state atom. A Fermi model is used that takes into account all angular-momentum couplings comparable to the e- + 5S1 / 2 scattering interaction strength. The model includes S- and P-wave singlet and triplet e- + 5S1 / 2 scattering, the fine-structure of the Rydberg atom as well as the hyperfine-structure of the 5S1 / 2 atom. The effects of these couplings on the adiabatic molecular potentials are discussed. We calculate bound-state energies, lifetimes, and electric and magnetic dipole moments for the 87Rb(nDj + 5S1 / 2) molecules in all potentials. The hyperfine structure gives rise to mixed singlet-triplet potentials in both low- and high- l molecular classes. These spin-mixed potentials are deep enough to sustain bound states, which were recently observed in low- l Cs2 molecules. We also study the effects of the hyperfine structure on the deep 3S and 3P adiabatic molecular potentials in both Rb2 and Cs2 molecules.
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.
Neutralization distances of Ar^Z+ Rydberg ions interacting with solid surfaces
NASA Astrophysics Data System (ADS)
Majkic, M. D.; Nedeljkovic, N. N.; Galijas, S. M. D.
2008-07-01
We apply the recently developed time-symmetrized, two-state vector model to investigate the intermediate stages of the electron capture into the Rydberg states of multiply charged Ar^Z+ ions (core charge Z >> 1, principal quantum number n_A >> 1) escaping Al-solid surface at low velocity. The simple analytical formulae derived for the corresponding neutralization rates enable us to analyze the neutralization distances for the low-l Rydberg states (n_A,l_A,m_A), for different charge states Z of the ion. It is found that the inclusion of core polarization significantly reduces the neutralization distances. The neutralization distances for the highest Rydberg levels that can be populated in the vicinity of solid surface are in agreement with the data deduced from experiments in which the kinetic energy gain due to the image acceleration of the ions is measured.
Geometry dependent suppression of collective quantum jumps in Rydberg atoms
NASA Astrophysics Data System (ADS)
Lees, Eitan; Clemens, James
2015-05-01
We consider N driven, damped Rydberg atoms in different spatial arrangements. Treating the atoms as two-level systems we model the coupling to the environment via the Lehmberg-Agarwal master equation which interpolates between fully independent and fully collective spontaneous emission depending on the specific locations of the atoms. We also include a collective dipole-dipole energy shift in the excited Rydberg state which leads to collective quantum jumps in the atomic excitation when the system is driven off resonance. We show that the quantum jumps are suppressed as the system makes a transition from independent to collective emission as the spacing of a linear array of atoms is decreased below the emission wavelength.
Dynamics of oxygen Rydberg atom generation following O 1s inner-shell excitation of H{sub 2}O
Gejo, T., E-mail: gejo@sci.u-hyogo.ac.jp; Ikegami, T.; Honma, K. [University of Hyogo, Koto 3-2-1, Kamigori-cho, Ako-gun, Hyogo 678-1297 (Japan); Takahashi, O. [Hiroshima University, 2-2 Kagamiyama 1-chome, Higashihiroshima 739-8512 (Japan); Shigemasa, E. [UVSOR Facility, Institute for Molecular Science, 38 Nishigo-Naka, Myodaiji, Okazaki 444-8585 (Japan); Hikosaka, Y. [Department of Environmental Science, Niigata University, 8050, Ikarashi 2-no-cho, Nishi-ku, Niigata 950-2181 (Japan); Tamenori, Y. [JASRI, Koto 1-1-1, Sayo-cho, Hyogo 679-5198 (Japan)
2014-06-07
The emission of low-energy electrons from H{sub 2}O has been investigated at photon excitation energies in the vicinity of the O 1s ionization threshold. Neutral oxygen Rydberg atoms (O*) were found to form, and the correlation between the initial inner-shell excited state of H{sub 2}O and the Rydberg state of O* was determined. The initially excited electron in a Rydberg orbital is shown to remain associated with O* even after the cleavage of two O-H bonds. We also show that the energy discrepancy between two Rydberg states of H{sub 2}O and O* can be explained by the influence of the post-collision interaction, which becomes stronger as the excitation energy approaches the 1s ionization threshold.
Solid helium. I. Ground-state energy calculated by a lowest-order constrained-variation method
NASA Astrophysics Data System (ADS)
Svorstřl, Otto; Řstgaard, Erlend
1986-11-01
The ground-state energy of solid helium is calculated by means of a modified variational lowest-order constrained-variation (LOCV) method. Both 3He and 4He in the bcc, fcc, and hcp structures, as well as two possible spin configurations for 3He, are considered, and the calculations are done for five different two-body potentials. Theoretical results for the ground-state energy per particle are -0.3 to + 1.8 K for solid 3He at a particle density of 0.42?-3 or a molar volume of 24 cm3/mol, and -6.1 to -3.2 K for solid 4He at a particle density of 0.50?-3 or a molar volume of 20 cm3/mol, where ?=2.556 Å. The corresponding experimental results are -1.0 and -5.6 K, respectively. For higher densities, our theoretical results are in even better agreement with experimental results.
A universal approach to Rydberg spectral line shapes in plasmas
NASA Astrophysics Data System (ADS)
Mossé, C.; Calisti, A.; Stamm, R.; Talin, B.; Bureyeva, L. A.; Lisitsa, V. S.
2004-03-01
A universal approach for the calculation of Rydberg atom line shapes in plasmas is developed. This approach goes far beyond the calculation capabilities of the standard models. It is based on analytical formulae for the intensity distribution in radiation transitions n - n' between highly excited atomic states with large values of principal quantum numbers n, n' Gt 1, with Dgrn = n - n' Lt n, and on the frequency fluctuation model to account for ion thermal motion effects. The theory allows us to describe a transition from the static to the impact broadening domains for every hydrogen spectral line. The specific cases of broadening of Hn-agr(Dgrn = 1) and Hn-bgr(Dgrn = 2) lines are considered in detail for various values of plasma parameters. The line shapes are presented in a universal manner as functions of the relative frequency splitting and of the fluctuation rate ngr of the ion plasma microfield, using dimensionless variables. For small values of ngr, the static line shapes which generalize the well-known Underhill-Waddell data for the Rydberg state case are presented. For large values of ngr, the transition to impact ion broadening is observed, resulting in a narrowing effect. A comparison with the hydrogen Hagr line shape calculations shows a good agreement between the universal approach for Rydberg lines and traditional spectral line shapes.
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)
Strongly Correlated Gases of Rydberg-Dressed Atoms: Quantum and Classical Dynamics
Pupillo, G.; Micheli, A.; Zoller, P. [Institute for Theoretical Physics, University of Innsbruck, and Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences, Innsbruck (Austria); Boninsegni, M. [Department of Physics, University of Alberta, Edmonton, Alberta, T6G 2J1 (Canada); Institute for Theoretical Physics, University of Innsbruck, and Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences, Innsbruck (Austria); Lesanovsky, I. [School of Physics and Astronomy, University of Nottingham, Nottingham (United Kingdom)
2010-06-04
We discuss techniques to generate long-range interactions in a gas of ground state alkali atoms, by weakly admixing excited Rydberg states with laser light. This provides a tool to engineer strongly correlated phases with reduced decoherence from inelastic collisions and spontaneous emission. As an illustration, we discuss the quantum phases of dressed atoms with dipole-dipole interactions confined in a harmonic potential, as relevant to experiments. We show that residual spontaneous emission from the Rydberg state acts as a heating mechanism, leading to a quantum-classical crossover.
NASA Astrophysics Data System (ADS)
Hakalla, Rafa?; Zachwieja, Miros?aw; Szajna, Wojciech
2014-06-01
So far unobserved in the 12C17O isotopologue, the 1-?? progression of the Ĺngström (B1?+-A1?) 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 B1?+ and A1? 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 Ĺngström band system in the 12C17O molecule. We have also determined the value of the ?G1/2 vibrational quantum, the isotope shifts, as well as the main, isotopically invariant parameters of the B1?+ Rydberg state in the CO molecule within the Born-Oppenheimer approximation. For the A1?, ?=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 B1?+, ?=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.
NASA Astrophysics Data System (ADS)
Man?ev, I.; Milojevi?, N.; Belki?, D.
2015-03-01
The four-body boundary-corrected first Born (CB1-4B) approximation is used to compute cross sections for single electron capture from helium targets by fully stripped ions. The projectile ions are H+, He2+, Li3+, Be4+, B5+, C6+, N7+, O8+, and F9+. An extensive list of theoretical state-to-state cross sections in these collisions at energies ranging from 20 to 10 000 keV/amu is given. This list includes the state-selective cross sections Qnlm for each individual triple of the usual quantum numbers { n , l , m } of the final hydrogen-like states alongside Qnl and Qn for the pertinent sub-shells and shells where the respective summations over m and { l , m } have been carried out. The maximal value of the principal quantum number n was chosen to vary from 4 (H+) to 10 (F9+) so as to satisfy the condition n ?ZP, where ZP is the nuclear charge of the projectile. Usually, the largest cross sections stem from those values of n that match the projectile charge (n =ZP) . The total cross sections for capture summed over all the quantum numbers { n , l , m } are also tabulated. The overall goal of this study is to fill in lacunae in the existing databases of charge exchange cross sections that are needed in several inter-disciplinary fields. For example, in particle transport physics, which is of utmost importance in such emerging branches as hadron therapy, these cross sections constitute a part of the multifaceted input data for stochastic simulations of energy losses of multiply charged ions in matter, including tissue. Other significant uses of the present data are anticipated in charge exchange diagnostics within thermonuclear research project as well as in applications covering the relevant parts of plasma physics and astrophysics.
Heating and cooling of an ultra-cold neutral plasma by Rydberg atoms
NASA Astrophysics Data System (ADS)
Tate, Duncan; Crockett, Ethan; Newell, Ryan
2015-05-01
We have experimentally demonstrated a mechanism for controlling the expansion rate of an ultra-cold neutral plasma (UNP) so that it is different from the value determined by the photo-ionizing laser frequency. We achieved this by adding Rydberg atoms to the UNP 10-20 ns after its creation. Specifically, we added nd5 / 2 state atoms with n = 24- 60 to UNPs with initial electron temperatures, Te , 0, in the range 10-250 K. The evidence is both indirect, from the change in the electron evaporation rate from the UNP, and direct, from the change in the asymptotic plasma expansion velocity, v0, measured using the time-of-flight spectrum of Rb+ ions. In addition, the results strongly support the existence of a ``bottleneck'' in the state distribution of Rydberg atoms formed by three body recombination (TBR) where the binding energy of the bottleneck state is Eb ~ 2 . 3 ×kBTe , 0 . Finally, we show that the amount of heating or cooling is linear in the number density of Rydberg atoms added to the UNP for small Rydberg densities, but saturates at higher densities to a value that is determined solely by the Rydberg binding energy. These results are in good general agreement with Monte-Carlo calculations. Funded by NSF and Colby College.
Dipolar Rydberg-atom gas prepared by adiabatic passage through an avoided crossing
Wang, Limei; Zhang, Linjie; Li, Changyong; Yang, Yonggang; Zhao, Jianming; Raithel, Georg; Jia, Suotang
2015-01-01
The passage of cold cesium 49S$_{1/2}$ Rydberg atoms through an electric-field-induced multi-level avoided crossing with nearby hydrogen-like Rydberg levels is employed to prepare a cold, dipolar Rydberg atom gas. When the electric field is ramped through the avoided crossing on time scales on the order of 100~ns or slower, the 49S$_{1/2}$ population adiabatically transitions into high-\\emph{l} Rydberg Stark states. The adiabatic state transformation results in a cold gas of Rydberg atoms with large electric dipole moments. After a waiting time of about $1~\\mu$s and at sufficient atom density, the adiabatically transformed highly dipolar atoms become undetectable, enabling us to discern adiabatic from diabatic passage behavior through the avoided crossing. We attribute the state-selectivity to $m$-mixing collisions between the dipolar atoms. The data interpretation is supported by numerical simulations of the passage dynamics and of binary $m$-mixing collisions.
Few-Body and Many-Body Quantum Optics in Rydberg Media
NASA Astrophysics Data System (ADS)
Gorshkov, Alexey
2014-03-01
We theoretically describe the propagation of quantized light under the conditions of electromagnetically induced transparency (EIT) in systems involving Rydberg states. In these systems, EIT enables the mapping of strong interactions between Rydberg atoms onto strong interactions between photons. We show how to make photons massive and how to introduce attractive, repulsive, and dissipative interactions between them. We also find and study the propagation of solitonic bound states of photons in such a medium. Finally, we determine the peculiar spatiotemporal structure of the output of two complementary Rydberg-EIT-based light-processing modules: the recently demonstrated single-photon filter and the recently proposed single-photon subtractor, which, respectively, let through and absorb a single photon. Our approach paves the way for the generation of a variety of nonclassical states of light, the implementation of photon-photon quantum gates, and the study of many-body phenomena with strongly correlated photons.
Rydberg spectroscopy of a Rb MOT in the presence of applied or ion created electric fields.
Viteau, M; Radogostowicz, J; Bason, M G; Malossi, N; Ciampini, D; Morsch, O; Arimondo, E
2011-03-28
Rydberg spectroscopy of rubidium cold atoms trapped in a magneto-optical trap (MOT) was performed in a quartz cell. When electric fields acting on the atoms generated by a plate external to the cell were continuously applied, electric charges on the cell walls were created, as monitored on the Rydberg spectra. Avoiding accumulation of the charges and realizing good control over the applied electric field was instead obtained when the fields were applied only for a short time, typically a few microseconds. In a two-photon excitation via the 62P state to the Rydberg state, the laser resonant with the 52S-62P transition photoionizes the excited state. The photoionization-created ions produce an internal electric field which deforms the excitation spectra, as monitored on the Autler-Townes absorption spectra. PMID:21451625
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.
Adiabatic quantum computation with Rydberg-dressed atoms
NASA Astrophysics Data System (ADS)
Keating, Tyler; Goyal, Krittika; Jau, Yuan-Yu; Biedermann, Grant W.; Landahl, Andrew J.; Deutsch, Ivan H.
2013-05-01
We study an architecture for implementing adiabatic quantum computation with trapped neutral atoms. Ground-state atoms are dressed by laser fields in a manner conditional on the Rydberg blockade mechanism, thereby providing the requisite entangling interactions. As a benchmark, we study the performance of quantum annealing to the ground state of an Ising spin lattice. We model a proof-of-principle experiment in a realistic architecture, including details of the atomic implementation, with qubits encoded in the clock states of 133Cs. Numerical simulation yields fidelities >0.98 for up to four qubits, and implementations of 10-20 qubits are within the range of current technology.
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.
Radiative HELIUM-3 Capture by CARBON-12 to Excited States in OXYGEN-15
NASA Astrophysics Data System (ADS)
Abduljalil, Amir M.
The radiative ^3He capture reaction on ^{12}C was measured over the energy region E_{ rm 3_{He}} = 12-25 MeV. The gamma-ray was measured by two 25.4 cm long and 25.4 cm in diameter NaI(Tl) spectrometers surrounded by anticoincidence plastic shields. Excitation functions at theta_{rm lab} = 60^circ and 105 ^circ have been measured for captures populating the ground and various excited states of ^{15}O. Angular distribution have been measured at E_{rm 3 _{He}} = 18.9 MeV. The existence of giant resonances built on the excited states of ^{15}O was investigated. Calculations from a phenomenological direct-semidirect cluster model were performed to bound and unbound final states in ^{15}O to determine the magnitude and the energy dependence of the cross section as well as the angular distributions. The calculations showed a reasonable agreement with the excitation function.
Communication: atomic and molecular Rydbergs from water.
Rajput, Jyoti; Safvan, C P
2011-05-28
We report the formation of energetic neutral Rydberg hydrogen atoms and transient Rydberg molecular ions, [(H(2)O)(q+)](?) in ion-impact dissociation of isolated water molecules. The kinetic energy spectra of the neutral Rydberg H atoms are determined from the complete study of (H(?), H(+), O(+)) dissociation channel. This channel of water dissociation is suggested as a possible additional source of the energetic neutrals detected in upper atmospheres of extra solar planets, and of slow electrons which are known to play a major role in radiation induced damage to living cells. PMID:21639412
Radiative and Relativistic Effects in the Decay of Highly Excited States in Helium
NASA Astrophysics Data System (ADS)
Gorczyca, Thomas Ward; Rubensson, Jan-Erik; Sĺthe, Conny; Ström, Magnus; Agĺker, Marcus; Ding, Dajun; Stranges, Stefano; Richter, Robert; Alagia, Michele
2000-08-01
A recent experimental study [J.-E. Rubensson et al., Phys. Rev. Lett. 83, 947 (1999)] measured a significant fluorescence yield of the He( 2lnl') photoexcited resonances, showing major qualitative differences from nonrelativistic predictions. We present a further theoretical study of these states, and perform R-matrix multichannel quantum defect theory calculations to extract fluorescence and ionization cross sections. These theoretical results are in excellent agreement with newer, higher-resolution measurements. Radiative and spin-orbit effects are quantified and shown to play an important role in the overall characterization of highly excited states.
State-selective electron capture in low velocity multiply charged ion, helium collisions
Cassimi, A.; Duponchel, S.; Flechard, X.; Jardin, P.; Sortais, P.; Hennecart, D.; Olson, R.
1996-05-01
Recoil ion momentum spectroscopy has been applied to study low energy, state-selective single electron capture by highly charged projectiles. The specific systems investigated are fully stripped 6.82 keV/u Ne{sup 10+} and 6.75 keV/u Ar{sup 18+} on He. Measurements of the He{sup +} recoil ion longitudinal momenta are used to determine the final {ital n}-state dependence of the captured electron. Simultaneous measurement of the transverse momenta of the recoil ion yields information about the impact parameter dependence of the reaction and the reaction window for electron capture. {copyright} {ital 1996 The American Physical Society.}
Steady-state heat transfer to boiling liquid helium in simulated coil windings
Walstrom, P.L.
1981-01-01
The present data show that the worst case steady-state stability in the GE/LCT magnet windings is at a horizontal conductor orientation. The heat transfer improves with inclination of the conductor from horizontal. Calculations show that for these small regions normal zones will recover by cold-end conduction from the inclined conductor on either end.
Green's function Monte Carlo calculation for the ground state of helium trimers
Cabral, F.; Kalos, M.H.
1981-02-01
The ground state energy of weakly bound boson trimers interacting via Lennard-Jones (12,6) pair potentials is calculated using a Monte Carlo Green's Function Method. Threshold coupling constants for self binding are obtained by extrapolation to zero binding.
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.
Stabilization of circular Rydberg atoms by circularly polarized infrared laser fields
Askeland, S.; Soerngaard, S. A.; Nepstad, R.; Foerre, M. [Department of Physics and Technology, University of Bergen, N-5007 Bergen (Norway); Pilskog, I. [Department of Physics and Technology, University of Bergen, N-5007 Bergen (Norway); Laboratoire de Chimie Physique - Matiere et Rayonnement, Universite Pierre et Marie Curie - CNRS (UMR 7614), F-75231 Paris Cedex 05 (France)
2011-09-15
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.
NASA Astrophysics Data System (ADS)
Shastri, Aparna; Singh, Param Jeet; Krishnakumar, Sunanda; Mandal, Anuvab; Raja Sekhar, B. N.; D'Souza, R.; Jagatap, B. N.
2014-11-01
We report a comprehensive photoabsorption study of nitrous oxide (N2O) in the vacuum ultraviolet (45,000-95,000 cm-1) region using synchrotron radiation. The observed spectrum comprises of a few valence transitions and low lying Rydberg series converging to the two spin-orbit components (2?1/2,3/2) of the ground state of N2O+. Spectral analysis is aided by extensive quantum chemical calculations of vertical excited states, oscillator strengths and potential energy curves using the time dependent density functional theory. Vibronic bands observed in the first absorption system (45,000-60,000 cm-1) are assigned to hot band progressions in ?2? originating from v?=1 or 2. New insights into the assignment of the well-formed progression of bands in the X1?+?C1? system (60,000-72,000 cm-1) are afforded by consideration of the Renner-Teller interaction. A set of molecular vibrational parameters (?2=467 cm-1, x22=-2.9, ?=-0.24) for the C1? state are derived from a fitting of the experimental data. The 3p?1?+ state at ~77,600 cm-1 shows a large quantum defect (0.96) which is explained as arising due to mixed valence-Rydberg character. In the 85,000-95,000 cm-1 region, a number of absorption features are observed with greater clarity than in earlier photoabsorption studies and assigned to Rydberg series of type nl? (n=3,4; l=s,p,d; ?=?,?,?) and accompanying vibronic bands. This work has resulted in clarification of several discrepancies in earlier Rydberg series assignments. Additionally, the 3p? 3?- Rydberg state at 85,788 cm-1, the valence transition 7??3? (1?) at 87,433 cm-1 and the 3d? Rydberg series in the 91,700-92,600 cm-1 region are assigned for the first time.
Alignment of the 2p State of 2-Mev Amu Helium-Like Sulfur
Church, David A.; Kenefick, R. A.; Wang, D. W.; Watson, R. L.
1982-01-01
process than does a measurement of a total cross section, which averages over the states created with preferred directions of angular momentum. The production of collisional anisotropy in fast ions makes possible spectroscopic measurements of atomic... the target foil with only modest collision broadening. Thus the P radiation intensity and polarization are potentially sensitive to effects associated with near-surface excitation, while the P intensity and polarization reflect the bulk excitation...
Experimental investigations of the resonant dipole-dipole interaction between cold Rydberg atoms
NASA Astrophysics Data System (ADS)
Browaeys, Antoine
2015-05-01
This talk will present our on-going effort to control the dipole-dipole interaction between cold Rydberg atoms. In our experiment, we trap individual atoms in two-dimensional arrays of optical tweezers separated by few micrometers and excite them to Rydberg states using lasers. The arrays are produced by a spatial light modulator, which shapes the dipole trap beam. We can create almost arbitrary geometries of the arrays. We have measured the van der Waals interaction between two individual atoms, and show efficient Rydberg blockade in arrays of three atoms. We have also demonstrated the control of the interaction between atoms with microwave and DC electric fields. We observe in particular the coherent energy exchange between two atoms resulting from their dipole-dipole interaction. This control of the interaction will find applications in quantum state engineering, quantum information and quantum simulation.
Spectral properties of finite laser-driven lattices of ultracold Rydberg atoms
Tezak, Nikolas; Schmelcher, Peter
2010-01-01
We investigate the spectral properties of a finite laser-driven lattice of ultracold Rydberg atoms exploiting the dipole blockade effect in the frozen Rydberg gas regime. Uniform one-dimensional lattices as well as lattices with variable spacings are considered. In the case of a weak laser coupling, we find a multitude of many-body Rydberg states with well-defined excitation properties which are adiabatically accessible starting from the ground state. A comprehensive analysis of the degeneracies of the spectrum as well as of the single and pair excitations numbers of the eigenstates is performed. In the strong laser regime, analytical solutions for the pseudo-fermionic eigenmodes are derived. Perturbative energy corrections for this approximative approach are provided.
Preparation for Acceleration and Deceleration of Cold Rydberg Atoms in the Field of a Charged Wire
NASA Astrophysics Data System (ADS)
Goodsell, Anne; Nawarat, Poomirat; Harper, W. Colleen
2015-05-01
We are preparing for experiments using cold Rydberg atoms in linear Stark states. We cool and launch Rb atoms at 2-12 m/s toward a charged wire with a cylindrically-symmetric electric field. The cold cloud will be illuminated in mid-flight to promote atoms into the desired Rydberg state (e.g. n = 33-40). With a three-photon sequence we will access nf states and the nearby manifolds (parabolic quantum number 0 <=n1 <= (n -4)) with linear Stark shifts. This requires specific detuning of the the excitation laser, which allows us to selectively compare states that are strongly accelerated to states that are strongly decelerated. With the wire at +10 V, atoms launched at 10 m/s, and excitation near 750 ?m from the wire, the displacement during the Rydberg lifetime (e.g. n = 35, ? = 30 ?s) will be 200-300 ?m farther for extreme attracted states (n1 = 0) than for extreme repelled states (n1 = 31). Detection will occur by spatially-dependent field ionization. Observations of atoms with zero angular momentum around the wire can be extended to atoms with nonzero angular momentum and also to study the dynamics of Rydberg atoms with a quadratic Stark shift, building on previous work with ground-state atoms. (Current address: Rensselaer Polytechnic Institute, Troy, NY).
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.
Storage and control of optical photons using Rydberg polaritons.
Maxwell, D; Szwer, D J; Paredes-Barato, D; Busche, H; Pritchard, J D; Gauguet, A; Weatherill, K J; Jones, M P A; Adams, C S
2013-03-01
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. PMID:23521254
Observation of suprathermal helium at 1 AU: Charge states in CIRs
NASA Astrophysics Data System (ADS)
Hilchenbach, M.; Grünwaldt, H.; Kallenbach, R.; Klecker, B.; Kucharek, H.; Ipavich, F. M.; Galvin, A. B.
1999-06-01
We report on measurements of the He charge states as observed in recurring energetic particle events during the recent solar minimum in 1996. The time-of-flight mass spectrometer CELIAS/STOF on board the SOHO satellite has the capability of detecting energetic ions between 35 and 630 keV/q and determine the mass, energy and charge of each particle. Typically we observe a He+/He2+ ratio of 0.16 to 0.31 in the range of 25 to 150 keV/nuc. We discuss the implications of these observations on the existing models of particle acceleration in corotating interaction regions (CIRs), i.e. the location of the acceleration process of corotating particle events as observed near 1 AU.
Far-infrared Rydberg-Rydberg transitions in a magnetic field: Deexcitation of antihydrogen atoms
Wetzels, A.; Guertler, A.; Noordam, L. D.; Robicheaux, F. [FOM Institute for Atomic and Molecular Physics, Kruislaan 407, 1098 SJ Amsterdam (Netherlands); Department of Physics, Auburn University, Auburn, Alabama 36849 (United States)
2006-06-15
The dynamics of (de)excitation between highly excited Rydberg states (15
Ultrafast Dynamics of 1,3-Cyclohexadiene in Highly Excited States
Minitti, Michael P.
2011-01-01
The ultrafast dynamics of 1,3-cyclohexadiene has been investigated via structurally sensitive Rydberg electron binding energies and shown to differ upon excitation to the 1B state and the 3p Rydberg state. Excitation of ...
Measurement of holmium Rydberg series through magneto-optical trap depletion spectroscopy
NASA Astrophysics Data System (ADS)
Hostetter, J.; Pritchard, J. D.; Lawler, J. E.; Saffman, M.
2015-01-01
We report measurements of the absolute excitation frequencies of 165Ho 4 f116 s n s and 4 f116 s n d odd-parity Rydberg series. The states are detected through depletion of a magneto-optical trap via a two-photon excitation scheme. Measurements of 162 Rydberg levels in the range n =40 -101 yield quantum defects well described by the Rydberg-Ritz formula. We observe a strong perturbation in the n s series around n =51 due to an unidentified interloper at 48515.47(4) cm-1. From the series convergence, we determine the first ionization potential EIP=48565.910 (3 ) cm-1, which is three orders of magnitude more accurate than previous work. This work is an important step towards using Ho atoms for collective encoding of a quantum register.
Sub-Poissonian Statistics of Jamming Limits in Ultracold Rydberg Gases
Jaron Sanders; Matthieu Jonckheere; Servaas Kokkelmans
2015-04-10
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.
Surface-electrode decelerator and deflector for Rydberg atoms and molecules
NASA Astrophysics Data System (ADS)
Allmendinger, P.; Deiglmayr, J.; Agner, J. A.; Schmutz, H.; Merkt, F.
2014-10-01
A surface-electrode decelerator and deflector for Rydberg atoms and molecules has been developed with the goal of performing collisional experiments. Translationally cold H2 molecules in a supersonic beam were excited to Rydberg-Stark states of principal quantum number n =31, loaded into electric traps moving at a predetermined speed above the surface of a bent printed circuit board, decelerated, and deflected from the original direction of the supersonic beam by an angle of 10?. The phase-space characteristics of the deflected beam were characterized by measuring the time-of-flight distribution and images of the Rydberg molecules and comparing them to the results of numerical particle-trajectory simulations. More than 1000 H2 molecules were deflected per experimental cycle at a repetition rate of 25 Hz. The phase-space characteristics of the deflector make it attractive to study ion-molecule reactions at low collision energies.
Sub-Poissonian Statistics of Jamming Limits in Ultracold Rydberg Gases.
Sanders, Jaron; Jonckheere, Matthieu; Kokkelmans, Servaas
2015-07-24
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. PMID:26252679
Zhao, Jianming; Zhu, Xingbo; Zhang, Linjie; Feng, Zhigang; Li, Changyong; Jia, Suotang
2009-08-31
A high sensitivity spectroscopy of Rydberg atoms is presented by using electromagnetically induced transparency (EIT) in the 6S(1/2)-6P(3/2)-n D ladder-type system of cesium vapor cell at room temperature. The EIT spectra of 40 D Rydberg state are measured and the dependences of the EIT magnitude and linewidth on the coupling laser power are investigated in detail. The Rydberg EIT linewidth is measured to be about 5.6 MHz when the powers of probe and coupling lasers are 50 microW and 5.2 mW, respectively, and which is close to the natural linewidth of cesium atoms. The effect of double resonance optical pumping on EIT is also investigated. The fine structures of nD (n = 39-55) are measured and the experimental result is in agreement with quantum defect theory. PMID:19724582
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.
Hussain, Shahid; Saleem, M.; Rafiq, M.; Baig, M. A.
2006-08-15
We present measurements of photoionization cross sections of the 3p {sup 1}P and 3p {sup 3}P excited states of helium, at threshold and near-threshold region (0-0.2 Ry). The experiments have been performed using a dc glow discharge and employed the saturation technique to determine the photoionization cross sections. A smooth frequency dependence of the cross section has been observed for both the excited states in accordance to the theoretical calculations. The measured values of the photoionization cross section, using a simple experimental setup, are in good agreement with the earlier reported theoretical and experimental values.
Cornelius, K.R.; Olson, R.E. [Department of Physics, University of Missouri-Rolla, Rolla, Missouri 65401 (United States)
1999-06-01
The classical trajectory Monte Carlo method has been used to calculate the total electron capture and ionization cross sections for collisions between multiply charged ions and a Rydberg target. The Rydberg targets are prepared in an oriented, elliptic state prior to simulating the system. The electron capture cross sections show a strong dependence on eccentricity as well as target alignment over various reduced collisions speeds. Electron ionization cross sections are less effected by alignment and show very little dependence on eccentricity at the higher collision speeds. {copyright} {ital 1999 American Institute of Physics.}
Rydberg-Induced Solitons: Three-Dimensional Self-Trapping of Matter Waves
Maucher, F.; Henkel, N.; Pohl, T.; Saffman, M.; Krolikowski, W.; Skupin, S.
2011-04-29
We propose a scheme for the creation of stable three-dimensional bright solitons in Bose-Einstein condensates, i.e., the matter-wave analog of so-called spatiotemporal ''light bullets.'' Off-resonant dressing to Rydberg nD states is shown to provide nonlocal attractive interactions, leading to self-trapping of mesoscopic atomic clouds by a collective excitation of a Rydberg atom pair. We present detailed potential calculations and demonstrate the existence of stable solitons under realistic experimental conditions by means of numerical simulations.
Suppression of collective quantum jumps in Rydberg atoms by collective spontaneous emission
NASA Astrophysics Data System (ADS)
Cayayan, Lyndon; Pauley, Jacob; Clemens, James
2015-05-01
We consider a system of driven, damped Rydberg atoms with dipole-dipole energy shifts which can give rise to Rydberg blockade when the atoms are driven on resonance and collective quantum jumps when the atoms are driven off resonance. For the damping we consider both independent and collective spontaneous emission. For independent emission a quasiclassical model predicts a bistable steady state and quantum fluctuations drive collective jumps between the two bistable branches. We show that collective spontaneous emission strongly suppresses the bistability and therefore suppresses the collective quantum jumps.
Coherent manipulation of cold Rydberg atoms near the surface of an atom chip
Carter, J D
2013-01-01
Coherent superpositions of the 49s and 48s Rydberg states of cold Rb atoms were studied near the surface of an atom chip. The superpositions were created and manipulated using microwaves resonant with the two-photon 49s-48s transition. Coherent behavior was observed using Rabi flopping, Ramsey sequences, spin-echo and spin-locking. These results are discussed in the context of Rydberg atoms as electric field noise sensors. We consider the coherence of systems quadratically coupled to noise fields with 1/f^k power spectral densities (k \\approx 1).
Two Dimensional Non-commutative Space and Rydberg Atom Model
NASA Astrophysics Data System (ADS)
Chung, Won Sang
2015-06-01
In this paper we consider the case of only space-space non-commutativity in two dimension. We also discuss the Rydberg atom model in this space and use the linear realization of the coordinate and momentum operators to solve the Schrödinger equation for the Rydberg atom through the standard perturbation method. Finally, the thermodynamics for the Rydberg atom model is discussed.
NASA Astrophysics Data System (ADS)
Ivanov, L. N.; Ivanova, E. P.; Knight, L. V.; Molchanov, A. G.
1996-06-01
This is a theoretical study of argon plasma under conditions, where Ne- and Na-like ionization stages are dominant. Balance equations are generalized to treat 37 3l states of Ne-like ion and 37 adjacent series of Rydberg states of Na-like ion simultaneously. This allows us to include in the kinetics a diffusion-like motion of the state of the system "Ne-like ion plus one electron" through the multitude of excited levels spread over an energy region of 50 eV. The populations Ni - i (i = (1, ..., 37)) of the Ne-like ion states are introduced explicitly; those of adjacent 37 Rydberg series are accounted for through continuous functions Ni(?). These functions describe the population distribution within each Rydberg series dependent on the Rydberg electron enegy ?. The elementary processes of the collisionalradiative model connecting all Ne- and Na-like states, as well as processes of redistribution of populations inside each Rydberg series, are accounted for. The rate coefficients for all processes within the Ne-like residue have been calculated previously, using a detailed many-body relativistic theory. The dielectric capture cross sections and autoionization probabilities are presented as analytical continuation of the collisional excitation cross sections. The excited-excited states transitions are included. The rest of the processes are treated in a simple semiclassical approximation. The Lotz formula is generalized by unambiguous analytical continuation to cover the case of bound-bound transitions between Rydberg states of Na-like ions. The radiation reabsorption in a long plasma cylinder is included through Biberman-Holstein coefficients for all transitions. The inclusion of Na-like states, accounting for diffusion-like processes, increases the population inversion for the "lasing candidates" by at least a factor of two for a wide range of plasma conditions. This is important for the ionization equilibrium too. Besides, the functions Ni(?) bear diagnostic information. Detailed calculations have been done for the homogeneous steady-state Maxwellian plasma. The role of transient processes in the population inversion creation is under discussion.
Studies of singlet Rydberg series of LiH derived from Li(nl) + H(1s), with n ? 6 and l ? 4
NASA Astrophysics Data System (ADS)
Gim, Yeongrok; Lee, Chun-Woo
2014-10-01
The 50 singlet states of LiH composed of 49 Rydberg states and one non-Rydberg ionic state derivable from Li(nl) + H(1s), with n ? 6 and l ? 4, are studied using the multi-reference configuration interaction method combined with the Stuttgart/Köln group's effective core potential/core polarization potential method. Basis functions that can yield energy levels up to the 6g orbital of Li have been developed, and they are used with a huge number of universal Kaufmann basis functions for Rydberg states. The systematics and regularities of the physical properties such as potential energies, quantum defects, permanent dipole moments, transition dipole moments, and nonadiabatic coupling matrix elements of the Rydberg series are studied. The behaviors of potential energy curves and quantum defect curves are explained using the Fermi approximation. The permanent dipole moments of the Rydberg series reveal that they are determined by the sizes of the Rydberg orbitals, which are proportional to n2. Interesting mirror relationships of the dipole moments are observed between l-mixed Rydberg series, with the rule ?l = ą1, except for s-d mixing, which is also accompanied by n-mixing. The members of the l-mixed Rydberg series have dipole moments with opposite directions. The first derivatives of the dipole moment curves, which show the charge-transfer component, clearly show not only mirror relationships in terms of direction but also oscillations. The transition dipole moment matrix elements of the Rydberg series are determined by the small-r region, with two consequences. One is that the transition dipole moment matrix elements show n-3/2 dependence. The other is that the magnitudes of the transition dipole moment matrix elements decrease rapidly as l increases.
Studies of singlet Rydberg series of LiH derived from Li(nl) + H(1s), with n ? 6 and l ? 4.
Gim, Yeongrok; Lee, Chun-Woo
2014-10-14
The 50 singlet states of LiH composed of 49 Rydberg states and one non-Rydberg ionic state derivable from Li(nl) + H(1s), with n ? 6 and l ? 4, are studied using the multi-reference configuration interaction method combined with the Stuttgart/Köln group's effective core potential/core polarization potential method. Basis functions that can yield energy levels up to the 6g orbital of Li have been developed, and they are used with a huge number of universal Kaufmann basis functions for Rydberg states. The systematics and regularities of the physical properties such as potential energies, quantum defects, permanent dipole moments, transition dipole moments, and nonadiabatic coupling matrix elements of the Rydberg series are studied. The behaviors of potential energy curves and quantum defect curves are explained using the Fermi approximation. The permanent dipole moments of the Rydberg series reveal that they are determined by the sizes of the Rydberg orbitals, which are proportional to n(2). Interesting mirror relationships of the dipole moments are observed between l-mixed Rydberg series, with the rule ?l = ą1, except for s-d mixing, which is also accompanied by n-mixing. The members of the l-mixed Rydberg series have dipole moments with opposite directions. The first derivatives of the dipole moment curves, which show the charge-transfer component, clearly show not only mirror relationships in terms of direction but also oscillations. The transition dipole moment matrix elements of the Rydberg series are determined by the small-r region, with two consequences. One is that the transition dipole moment matrix elements show n(-3/2) dependence. The other is that the magnitudes of the transition dipole moment matrix elements decrease rapidly as l increases. PMID:25318728
Coherence and Rydberg Blockade of Atomic Ensemble Qubits
NASA Astrophysics Data System (ADS)
Ebert, M.; Kwon, M.; Walker, T. G.; Saffman, M.
2015-08-01
We demonstrate |W ? state encoding of multiatom ensemble qubits. Using optically trapped Rb atoms, the T2 coherence time is 2.6(3) ms for N Ż=7.6 atoms and scales approximately inversely with the number of atoms. Strong Rydberg blockade between two ensemble qubits is demonstrated with a fidelity of 0.89(1), and with a fidelity of 1.0 when postselected on a control ensemble excitation. These results are a significant step towards deterministic entanglement of atomic ensembles.
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.
The kicked Rydberg atom: Regular and stochastic motion
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.
Enhancement of Rydberg Atom Interactions Using ac Stark Shifts
Bohlouli-Zanjani, P.; Petrus, J. A.; Martin, J. D. D.
2007-05-18
The ac Stark effect was used to induce resonant energy transfer between translationally cold {sup 85}Rb Rydberg atoms. When a 28.5 GHz dressing field was set at specific field strengths, the two-atom dipole-dipole process 43d{sub 5/2}+43d{sub 5/2}{yields}45p{sub 3/2}+41f was dramatically enhanced, due to induced degeneracy of the initial and final states. This method for enhancing interactions is complementary to dc electric-field-induced resonant energy transfer, but has more flexibility due to the possibility of varying the applied frequency.
Landau-Zener Transitions in Frozen Pairs of Rydberg Atoms
Saquet, Nicolas; Cournol, Anne; Beugnon, Jerome; Robert, Jacques; Pillet, Pierre; Vanhaecke, Nicolas [Laboratoire Aime Cotton, CNRS, Batiment 505, Universite Paris-Sud, 91405 Orsay (France)
2010-04-02
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.
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.
Mid-IR laser action in the H 3 Rydberg molecule and some possible astrophysical implications
Cohen, Ronald C.
in supersonic plasmas and assigned to d to p transitions in tri-atomic hydrogen Rydberg states. Possible searching for IR spectra of molecular ions in pulsed planar supersonically expanding plasmas with cavity. The calculated line positions have a precision of about 13 cm-1. Proceedings of the International Conference
Capture of slow antiprotons by helium atoms
Shevchenko, N.V. [Joint Institute for Nuclear Research, Dubna, 141980 (Russian Federation); Nuclear Physics Institute, 25068 Rez (Czech Republic); Revai, J. [Research Institute for Particle and Nuclear Physics, H-1525 Budapest, P.O.B. 49 (Hungary)
2005-10-26
A consistent quantum mechanical calculation of partial cross sections leading to different final states of antiprotonic helium atom was performed. Calculations were carried out for a wide range of antiprotonic helium states and incident energies of the antiproton below the first ionization threshold of the He atom.
Allen, J.S.; Chung, S.; Lin, C.C. )
1990-02-01
Electron-impact excitation of the {ital x} {sup 1}{Sigma}{sub g}{sup {minus}}, {ital y} {sup 1}{Pi}{sub g}, and {ital o}{sub 3} {sup 1}{Pi}{sub u} Rydberg electronic states of the nitrogen molecule has been studied. We have measured the maximum electron-impact optical-emission cross sections of many vibrational bands of the {ital y} {sup 1}{Pi}{sub g}{r arrow}w {sup 1}{Delta}{sub u}, {ital y} {sup 1}{Pi}{sub g}{r arrow}a{prime} {sup 1}{Sigma}{sub u}{sup {minus}}, and {ital x} {sup 1}{Sigma}{sub g}{sup {minus}}{r arrow}a{prime} {sup 1}{Sigma}{sub u}{sup {minus}} electronic transitions. The maximum values of the optical-emission cross sections of these band systems are typically less than or on the order of 10{sup {minus}20} cm{sup 2}. The dependence of the emission cross sections of selected bands on electron energy has been studied. The excitation functions of the {ital y}{r arrow}{ital a}{prime} and {ital x}{r arrow}{ital a}{prime} bands have similar shapes below about 50 eV with a peak near 32 eV, and are approximately proportional to 1/{ital E} at high energies. We have measured the emission cross section of the {ital o}{sub 3} {sup 1}{Pi}{sub u}{r arrow}a {sup 1}{Pi}{sub g}(0,0) band as a function of electron energy. The excitation function of the {ital o}{sub 3}{r arrow}a(0,0) band has a broader shape than the excitation functions of the {ital y}{r arrow}{ital w}, {ital y}{r arrow}{ital a}{prime}, and {ital x}{r arrow}{ital a}{prime} bands. We have calculated Franck-Condon factors for the {ital y}{r arrow}{ital w}, {ital y}{r arrow}{ital a}{prime}, and {ital x}{r arrow}{ital a}{prime} band systems and compare them with the experimental emission cross sections of these band systems. The apparent electron-impact-excitation cross sections of the vibrational levels of the {ital x} and {ital y} electronic states are estimated.
Ershova, Olga V; K?os, Jacek; Besley, Nicholas A; Wright, Timothy G
2015-01-21
We present new potential energy surfaces for the interaction of NO(C?(2)?) with each of Ne, Kr, and Xe. The potential energy surfaces have been calculated using second order Mřller-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. PMID:25612713
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.
Continetti, Robert E.
3 and D3 Christopher M Laperle, Jennifer E Mann, Todd G Clements and Robert E Continetti1 Department of fast (12 keV) H3 + and D3 + with Cs yields insights into the nuclear motion during dissociation2 states for D3. This data provide an empirical benchmark for the refinement of theoretical models
Chu, Shih-I; Zhou, Zhongyuan
2005-02-28
A spin-dependent density-functional approach for the calculation of highly and multiply excited state of atomic system is proposed based on the localized Hartree-Fock density-functional method and Slaters diagonal sum rule. In this approach...
Measurement and numerical calculation of Rubidium Rydberg Stark spectra
Grimmel, Jens; Karlewski, Florian; Jessen, Florian; Reinschmidt, Malte; Sándor, Nóra; Fortágh, József
2015-01-01
We report on the measurement of Stark shifted energy levels of $^{87}$Rb Rydberg atoms in static electric fields by means of electromagnetically induced transparency (EIT). Electric field strengths of up to 500V/cm, ranging beyond the classical ionisation threshold, were applied using electrodes inside a glass cell with rubidium vapour. Stark maps for principal quantum numbers $n=35$ and $n=70$ have been obtained with high signal-to-noise ratio for comparison with results from ab initio calculations following the method described in [M. L. Zimmerman et al., Phys. Rev. A 20, 2251 (1979)], which was originally only verified for states around $n=15$. We also calculate the dipole matrix elements between low-lying states and Stark shifted Rydberg states to give a theoretical estimate of the relative strength of the EIT signal. The present work significantly extends the experimental verification of this numerical method in the range of both high principal quantum numbers and high electric fields with an accuracy of...
Measurement and numerical calculation of Rubidium Rydberg Stark spectra
NASA Astrophysics Data System (ADS)
Grimmel, Jens; Mack, Markus; Karlewski, Florian; Jessen, Florian; Reinschmidt, Malte; Sándor, Nóra; Fortágh, József
2015-05-01
We report on the measurement of Stark shifted energy levels of 87Rb Rydberg atoms in static electric fields by means of electromagnetically induced transparency (EIT). Electric field strengths of up to 500 V cm?1, ranging beyond the classical ionization threshold, were applied using electrodes inside a glass cell with rubidium vapour. Stark maps for principal quantum numbers n = 35 and n = 70 have been obtained with high signal-to-noise ratio for comparison with results from ab initio calculations following the method described in (Zimmerman et al 1979 Phys. Rev. A 20 2251), which was originally only verified for states around n = 15. We also calculate the dipole matrix elements between low-lying states and Stark shifted Rydberg states to give a theoretical estimate of the relative strength of the EIT signal. The present work significantly extends the experimental verification of this numerical method in the range of both high principal quantum numbers and high electric fields with an accuracy of up to 2 MHz.
Dipole-dipole interaction between rubidium Rydberg atoms
Altiere, Emily; Fahey, Donald P.; Noel, Michael W. [Physics Department, Bryn Mawr College, Bryn Mawr, Pennsylvania 19010 (United States); Smith, Rachel J.; Carroll, Thomas J. [Department of Physics and Astronomy, Ursinus College, Collegeville, Pennsylvania 19426 (United States)
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.