Bulletin of the American Physical Society
2006 37th Meeting of the Division of Atomic, Molecular and Optical Physics
Tuesday–Saturday, May 16–20, 2006; Knoxville, TN
Session W1: Poster Session III 
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Room: Knoxville Convention Center Ballroom AB 

W1.00001: ATOMIC AND MOLECULAR STRUCTURE, INTERACTIONS WITH STATIC FIELDS 

W1.00002: Boundary Solutions of the Twoelectron Schr\"{o}dinger Equation at Twoparticle Coalescences of the Atomic Systems Evgeny Liverts, Rajmund Krivec, Victor Mandelzweig, Miron Amusia The limit relations for the partial derivatives of the twoelectron atomic wave functions at the twoparticle coalescence lines have been obtained numerically using accurate CFHHM wave functions. The asymptotic solutions of the proper twoelectron Schr\"{o}dinger equation have been derived for both electronnucleus and electronelectron coalescence. It is shown that the solutions for the electronnucleus coalescence correspond to the ground and singly excited bound states, including triplet ones. The proper solutions at small distances $R$ from the triple coalescence point were presented as the second order expansion on $R$ and $\ln R$. The vanishing of the Fock's logarithmic terms at the electronnucleus coalescence line was revealed in the frame of this expansion, unlike the case of electronelectron coalescence. On the basis of the obtained boundary solutions the approximate wave function corresponding to both coalescence lines have been proposed in the twoexponential form with no variational parameters. [Preview Abstract] 

W1.00003: Temperature dependence of argon excimer emission from pulsed discharge excited argon clusters Mark Masters, Mike De Armond, Clint Reynolds, Hans Suedhoff Argon second continuum excimer emission is observed from a pulsed discharge excited pulsed supersonic argon expansion. The expansion nozzle consists of a temperature controlled, 15 cm long slit with a variable width (35 $\mu $m to 250 $\mu $m). The intensity of the argon excimer emission near 126 nm is investigated as a function of the width of the expansion nozzle slit, temperature of the expansion nozzle and position within the cathodeanode gap. The pressure within the nozzle has been measured as 24 bar and the excitation consists of a 50 ns negative current pulse of about 15kV and 700A. The observation of the emission depends directly on the size and quantity of clusters formed in the expansion. To determine the dependence of the emission upon clusters and the cluster size distribution, the mean cluster size is diminished by increasing the expansion nozzle and gas temperature. The temporal evolution of the second continuum emission and the observed spectra are presented as a function of nozzle temperature and slit width. [Preview Abstract] 

W1.00004: Mixing of rovibrational levels of the $3\,^3\Pi$ and $4\,^3\Pi$ states of NaK due to nonadiabatic coupling A. P. Hickman, R. D. Miles, D. O. Kashinski, J. Huennekens, L. Morgus We report further results of our investigation of the excited $3\,^3\Pi$ and $4\,^3\Pi$ electronic states of NaK. These electronic states exhibit an avoided crossing, and many rovibrational levels are mixtures of both electronic components. The hyperfine structure and energies of numerous rovibrational levels were determined using the Dopplerfree, perturbationfacilitated opticaloptical double resonance (PFOODR) technique [J.~Chem.~Phys.\ {\bfseries 122}, 144313 (2005)]. However, the hyperfine spectra of the $3\,^3\Pi$ and $4\,^3\Pi$ levels are very similar, and excitation spectra to the two states are difficult to distinguish. Further work has shown that boundfree spectroscopy provides a means of differentiating the two electronic states and even estimating the mixing fractions for pairs of rovibrational levels. The nonadiabatic coupling between the $3\,^3\Pi$ and $4\,^3\Pi$ states has been exactly formulated in terms of the diabatic potential curves, and the diabatic curves have been determined that best fit the experimental data. Comparison between experimental and theoretical mixing fractions will be presented. [Preview Abstract] 

W1.00005: Fine and hyperfine structure of rovibrational levels of the NaK $1\,^3\!\Delta$ states from $v=3$ to near the dissociation limit A. D. Wilkins, S. Jawalkar, J. Huennekens, A. P. Hickman, L. Morgus Our previous highresolution spectroscopic studies of the fine and hyperfine structure of rovibrational levels of the $1\,^3\!\Delta$ state of NaK have been extended to include vibrational levels up to $v = 59$, the highest of which are within $4~\mathrm{cm}^{1}$ of the dissociation limit. Using the IPA method, a potential curve was determined that reproduces all measured levels ($3 \le v \le 59$) to an accuracy of $\sim 0.026\,\mathrm{cm}^{1}$, and $C_6$ and $C_8$ coefficients have also been determined from the long range potential. The fine and hyperfine structure of the $1\,^3\!\Delta$ rovibrational levels were analyzed to determine the values $A_v$ and $b_{\mathrm{F}}$ of the spinorbit coupling constant and the hyperfine Fermi contact constant. The measured fine and hyperfine structure for $v$ in the range $44 \le v \le 48$ exhibits anomalous behavior due to the mixing between the $1\,^3\!\Delta$ and $1\,^1\!\Delta$ states. The theoretical method has been extended to treat this interaction, and the results provide an accurate representation of the complicated patterns that arise. {\it Ab initio} calculations of the spinorbit coupling constants $A_v$ are also underway. [Preview Abstract] 

W1.00006: Spinorbit coupling of the NaK $3^{3}\Pi$ and $3^{1}\Pi$ states: Determination of the coupling constant and observation of quantum interference effects S. Eckel, J. Huennekens We have studied the mutually perturbing $3^{3}\Pi_{\Omega = 0}(v = 32, J = 19) \sim 3^{1}\Pi_{\Omega = 1}(v = 6, J = 19)$ levels of NaK that are coupled together by the spinorbit interaction. This coupling is nominally forbidden by the $\Delta \Omega = 0$ selection rule for spinorbit perturbations. However $3^{3}\Pi$ levels labeled by different values of $\Omega$ are mixed by rotational coupling; i.e. the $3^{3}\Pi _{\Omega }$ levels are best described by a coupling scheme intermediate between Hund's cases (a) and (b). Thus the $3^{1}\Pi_{\Omega = 1}$ level couples to the $3^{3}\Pi_{\Omega = 0}$ level via the small admixture of $3^{3}\Pi_{\Omega = 1}$ character in the latter. The $3^{3}\Pi_{\Omega = 0}(v = 32, J = 19) \sim 3^{1}\Pi_{\Omega = 1}(v = 6, J = 19)$ $f$ symmetry pair is of particular interest since it appears to be very close to a 5050 mixture of triplet and singlet character, and the splitting between these levels provides a direct measure of the $3^{3}\Pi \sim 3^{1}\Pi$ spinorbit coupling constant. Excitation spectra of the $3^{3}\Pi_{\Omega =0}(v = 32, J = 19) \sim 3^{1}\Pi_{\Omega = 1}(v = 6, J = 19)$ $e$ symmetry pair through the mixed ``window'' levels $1(b)^{3}\Pi_{\Omega = 0}(v = 17, J = 18, 20) \sim 2(A)^{1}\Sigma^{+}(v = 18, J = 18, 20)$ display dramatic quantum interference effects associated with ``singlet'' and ``triplet'' excitation channels. Complete cancellation for one or the other of the two upper states is observed for excitation from the predominantly triplet members of the window level pairs. [Preview Abstract] 

W1.00007: Magnetism in Clusters of Cobalt and Chromium. Louis Bloomfield, Forrest Payne, Wei Jiang We report on measurements of magnetism in cobalt and chromium clusters of between 10 and 200 atoms. Both elements show magnetic order that exceeds that of the bulk. The low dimensionality of clusters allows them to retain much of their atomic magnetism. While cobalt is already ferromagnetic in the bulk, it shows increasing magnetization per atom as the cluster size decreases. Chromium, however, is antiferromagnetic in the bulk, so the observed magnetization in chromium clusters is more exotic. [Preview Abstract] 

W1.00008: Tensor Polarizabilities of Sodium Rydberg States C.W.S. Conover, N.L. Beaird We have used a timedomain spectroscopy technique to measure transitions between fine structure levels of Na Rydberg d and p states in a static electric field. Transitions are driven by delayed pairs of intense subnanosecond halfcycle electric field pulses. With these measurements we have determined the finestructure splittings and tensor polarizabilities of the $n^*$d states for n = 15 to 24, and the $n^*$p states from n = 25 to 32. The results are more than an order of magnitude more accurate than earlier measurements of these quantities. [Preview Abstract] 

W1.00009: Accurate treatment of doublyexcited Rydberg resonance states and dcfield ionization rates of twoelectron systems John Heslar, ShihI Chu We present a complexscaling (CS)generalized pseudospectral (GPS) method in hyperspherical coordinates (HSC) for \emph{ab initio} and accurate treatment of the electron structure and quantum dynamics of twoelectron systems [1]. The GPS method allows nonuniform and optimal spatial discretization of the twoelectron Hamiltonian in HSC with the use of only a very modest number of grid points. The procedure is applied for the precision calculation of the energies and widths of doublyexcited Rydberg resonance states as well as the ionization rates of He atoms in intense dc fields. [1] J.~Heslar and S.~I.~Chu, Phys.\ Rev.\ A (submitted). [Preview Abstract] 

W1.00010: Production and sensitive detection of PbF molecules for an eEDM experiment. Neil ShaferRay, Christopher McRaven, Poopalasingam Sivakumar The stationary states of a molecule in a pure electric field are degenerate in the sign of the projection of total angular momentum on the field axis. A lifting of this $\pm $M$_{F}$ degeneracy would be an indication of CP (time reversal) symmetry violation. For heavy paramagnetic molecules, this CP violation would be attributed to an electron electric dipole moment (eEDM) and could at once separate Supersymmetric models from the Standard Model and explain why we are made of matter instead of antimatter. A major obstacle to observing CP violation in this way is that the background magneticfield induced splitting of the $\pm $M$_{F}$ degeneracy normally dwarfs any possible electricfield induced splitting. Here we report how the physics of $^{2}\Pi _{1/2}$ PbF can be exploited to gain extraordinary sensitivity to the eEDM while reducing the magnetic g factor to less than 10$^{7}$. A new radical beam source and sensitive resonance enhanced multiphoton ionization (REMPI) detection of PbF are reported. [Preview Abstract] 

W1.00011: QUANTUM OPTICS, MATTER OPTICS, AND COHERENT CONTROL 

W1.00012: Neutral Atom Lithography Using a Bright Metastable Helium Beam Claire V. Shean, Jason Reeves, Michael Keller, Matthias Riedmann, Harold Metcalf We have performed neutral atom lithography using a beam of metastable 2$\,^3$S Helium (He*) that is brightened sequentially by the bichromatic force and then optical molasses\footnote{M. Partlow et al., Phys. Rev. Lett {\bf 93}, 213004 (2004).}. We have successfully demonstrated this technique using a physical mask of fine mesh covering a self assembled monolayer (SAM) of nonanethiol over a 20 nm evaporated film of Au on a Si wafer substrate\footnote{Younan Xia et al. Chem. Mater. {\bf 7}, 2332 (1995)}. The 20 eV internal energy of He* damages the SAM so that those damaged molecules and the underlying Au layer can be removed using a wet chemical etch$^5$. Samples created this way have an edge resolution of $\sim \,$63 nm that we measured with an atomic force microscope. This technique has promise for creating nanostructured metamaterials with unusual optical properties. [Preview Abstract] 

W1.00013: Development of a highflux Ca atom interferometer Justin Paul, Dan Christensen, Rebecca Tang, Christopher Erickson, Jeremiah Birrell, Dallin Durfee We present progress towards a Ca atom interferometer. The device will utilize a thermal beam of atoms for simplicity and high signals. The atom waves will be split and recombined using a singlephoton transition at a wavelength of 657 nm. A unique alignment scheme will be used to reduce systematic drifts due to Doppler shifts. We are currently working to improve the linewidth of the 657 nm laser and constructing a 423 nm blue laser to transversely cool the atoms and to detect the output of the interferometer. We are also characterizing a thermal Ca beam using laser absorption and working on precise control of the temperature and flux of the beam. We are also evaluating a precision method to align the thermal beam relative to gravity using Fraunhofer diffraction. [Preview Abstract] 

W1.00014: Controlled entanglement of two atoms in movable traps Haian Wang, Peng Zhang, Michael Chapman, Li You We propose a scheme for controlled entanglement of two separately trapped atoms. In our setup, the two atoms become entangled after the two initially separated traps are translated towards each other, overlap, and moved apart adiabatically. Cumulative adiabatic phase shifts arising from atomic interactions during the protocol give rise to a final twoatom state that can be conveniently expressed in terms of separable states involving single atoms in well defined traps. We provide a thorough investigation of the efficiencies and effectiveness of our scheme. We further calibrate the dependence of the fidelities of the entangled states on the various control parameters such as the speed of the trap translation. Finally, we show that our setup possesses several advantages and can be easily employed to accomplish a nontrivial quantum gate. [Preview Abstract] 

W1.00015: Constructing atom optical elements from periodic potentials of finite length Michael W.J. Bromley, Oscar O. Salazar, Brett D. Esry The manipulation of the dispersion properties of a BoseEinstein condensate (BEC) with moving optical lattices has enabled considerable control of atomic matter waves and, more recently, the generation of bright matter wave solitons [1]. Here, we computationally propagate BEC's through periodic optical potentials of finite spatial/temporal lengths. It is seen that to vary the effective mass requires potentials that are relatively strong compared to the transverse waveguide confinement. The role of both the linear and nonlinear wave mechanics in practical issues such as loading the atoms into the potentials are explored. We also report on work in progress examining matter waves propagation through a chipbased magnetic lattice [2]. \\ $[1]$ Eiermann, B \textit{et.al} Phys.~Rev.~Lett. \textbf{92} 230401 (2004) \\ $[2]$ G{\"u}nther, A \textit{et.al} Phys.~Rev.~Lett. \textbf{95} 170405 (2005) [Preview Abstract] 

W1.00016: Beamsplitting of a BoseEinstein Condensate in a Microtrap by a Standing Light Wave Quentin Diot, Stephen Segal, Dana Anderson, Eric Cornell We have developed an inguide atom beamsplitter and demonstrated the coherent nature of the process by observing interference between the split wavepackets. Precooled atoms are captured by the onchip waveguide and trapped by confining fields in a ``microtrap'' region of the guide. Atoms are then evaporatively cooled to form a BoseEinstein condensate. Finally, we are able to split the condensate, propagate two wavepackets in opposite directions along the waveguide and read their relative phase by exposing the trapped BEC to a sequence of standing light pulses. We carefully aligned the standing light field with the waveguide by directly mounting mirrors on the chip substrate. Precooled atoms reach the trapping region by following the guide through a 180umheight tunnel under one of the mirrors. We control the phase shift between the two wavepackets by applying an external magnetic gradient parallel to the guide. After recombining the clouds, we observed coherence signals for up to 10 ms of propagation time. The inguide production of a condensate, the numerous wires and features available on the chip and the proven coherence of the beamsplitter, make this device a useful tool for understanding and improving the propagation of coherent atomic samples in waveguides. [Preview Abstract] 

W1.00017: Guiding atoms in a hollowcore photonic bandgap fiber Tetsu Takekoshi, Randy Knize We discuss the current progress of our experiment to guide rubidium atoms in hollowcore photonic bandgap fiber. The atoms are contained within the hollow region of the fiber by the dipole potential created with a strong reddetuned laser. This technique has several significant advantages over other atom guiding experiments using hollow core fiber. First, the design of the air/silica structure allows low attenuation propagation ($<$ 0.1 dB/m) at certain wavelengths down the hollow core. As a result, the optical potential is uniform over the length of the fiber. Also, the light field is almost exclusively inside the hollow core, and it is relatively easy to couple light into the fiber. Since the field inside the fiber can be relatively high, it is possible to detune the laser far from resonance while maintaining a strong dipole potential, and thereby greatly reduce the scattering rate. [Preview Abstract] 

W1.00018: Applications of cold, magneticallyguided atomic beams S.~E. Olson, R.~R. Mhaskar, G. Raithel In parallel with work aimed at developing a continuouswave atom laser in a highgradient magnetic guide, we are exploring tools suited to manipulate cold atomic beams in atom guides. We present an experimental demonstration of using RFfiltering to decrease the number of modes occupied by an atomic flow propagating in a highgradient atom guide. Through sufficient filtering of this type, a nearsinglemode guided atomic beam should be achievable, allowing basic atominterferometric experiments. We present a new inline beamsplitting scheme using RFdressedstate potentials. It is shown how this scheme could be employed to build fairly simple largearea Sagnac atom interferometers. Finally, we will present Monte Carlo collision simulations of novel evaporative cooling techniques in a guided atomic beam. [Preview Abstract] 

W1.00019: Donut modes and photonic hollow fibers: a possible scheme for atom transport Sandip Mitra, J. Smith, N. Chattrapiban, I. Arakelyan, W.T. Hill, III Bragg fibers are a specific class of photonic bandgap fibers that have the capacity to be optimized for lowloss transmission of ``donut'' modes. This ability makes these fibers attractive as possible tool for atom optics. One example would be to transport neutral atoms through harsh environments. This would be possible by copropagating a bluedetuned donut mode with the atoms through the fiber. We have studied the transmission efficiency of ``donut'' Bessel and LaguerreGaussian modes through a fiber designed to transmit 780 nm light both experimentally and theoretically. In this poster we will describe the results and discuss the prospects for atom loading and other applications. [Preview Abstract] 

W1.00020: Observation of quantum accelerator modes in Rb atoms Vijayashankar Ramareddy, Brian Timmons, Ghazal BehinAein, Peyman Ahmadi, Gil Summy We report the observation of Quantum Accelerator Modes (QAM) for cold Rb87 atoms. Quantum accelerator modes are produced by the diffraction of atomic De Broglie waves. When a standing light wave which acts as a thin phase grating is produced, a group of atoms that have certain initial velocity gets accelerated. The momentum gained by these atoms scales linearly with the number of kicks. Gravity plays an important role in QAM through the phase evolution of the De Broglie wave between any two kicks. QAM can be used in the study of quantum chaos and atom optics. [Preview Abstract] 

W1.00021: Loading and Manipulating Atoms on a Chip. David Aveline, Robert Thompson, Nathan Lundblad, Lute Maleki We describe a method of efficiently loading and manipulating neutral atoms in atom chip traps. Cooled 87Rb from a MOT is transported via coilbased magnetic traps into chipbased wire traps and precisely directed in wireguides. Our loading method begins with the collection of a MOT located 4 cm away from the chip's trapping region. At this distance, a conventional MOT of six beams can be made without obstruction from the chip and its mounting structure. The MOT's antiHelmholtz coils are aligned along an axis normal to the chip surface, and this pair of coils also serves as a magnetic quadrupole trap. A second pair of antiHelmholtz coils is centered on the chip's trapping region. Trading currents between the two coils smoothly translates a magnetic trap over to the chip region. Finally, the atoms transfer to a Ushaped wire on the chip surface. We have achieved near unity transfer efficiency. Once in the Utrap, the atoms can transfer into a Ztrap and single wire guides. We report on investigations of manipulating atoms with external gradients, and splitting into reflected and transmitted components as they traverse a potential barrier. We also discuss results of studies to precisely control the output coupling of the atoms into the guide. [Preview Abstract] 

W1.00022: Timedependent analysis of pulsed EIT processes in atomic clocks Thomas Zanon, Andrew Ludlow, Martin M. Boyd, Tanya Zelevinsky, Sebastian Blatt, Tetsuya Ido, Jun Ye Narrow resonances established via Electromagnetically Induced Transparency under continuous excitations have been proposed as new optical frequency standards using either single trapped ions $[1]$ or neutral atoms trapped in an optical lattice $[2,3]$. In a similar approach to ultra high resolution spectroscopy, time separated Dark Resonance pulses in a three level $\Lambda$ system have been proposed $[4]$ as an alternative clock interrogation tool for probing a narrow transition between two longlived states $[5,6]$. Pulse sequences are designed that mix steady states or transient regimes with a free evolution time of the metstable ground state coherence, with the goal to optimally recover the clock information prepared by EIT. RamanRamsey nutations are then demonstrated using a set of effective damped twolevel Optical Bloch equations. To evaluate potential accuracy of an EIT based clock, AC Stark shifts are carefully considered. These light shifts can be expressed as phase shifts in the cosine function describing the RamanRamsey oscillations resulting in a frequency shift of the central fringe minima. $[1]$I. Siemers et al, EuroPhys. Lett.\textbf{18}, 139 (1992).$[2]$R. Santra et al, Phys. Rev. Lett.\textbf{94}, 173002 (2005).$[3]$T. Hong et al, Phys. Rev. Lett.\textbf{94}, 050801 (2005).$[4]$T. Zanon et al, Phys. Rev. Lett.\textbf{94}, 193002 (2005).$[5]$J.E. Thomas et al, Phys. Rev. Lett.\textbf{48}, 867 (1982).$[6]$P. Knight, Nature.\textbf{297}, 16 (1982). [Preview Abstract] 

W1.00023: Generation, Storage, and Retrieval of SinglePhoton Pulses using Electromagnetically Induced Transparency Matthew Eisaman, Philip Walther, Axel Andre, Florent Massou, Michael Fleischhauer, Alexander Zibrov, Mikhail Lukin We demonstrate the use of electromagnetically induced transparency (EIT) for the controllable generation, transmission, and storage of single photons with tunable frequency, timing and bandwidth. We study the interaction of single photons produced in a `source' ensemble of rubidium87 atoms at room temperature with another `target' ensemble. This allows us to simultaneously probe the spectral and quantum statistical properties of narrowbandwidth singlephoton pulses, revealing that their quantum nature is preserved under EIT propagation and storage. We measure the time delay associated with the reduced group velocity of the singlephoton pulses and report observations of their storage and retrieval. Finally, we discuss experimental progress towards application of these results to longdistance quantum communication. [Preview Abstract] 

W1.00024: Optimal Control of Storage and Retrieval of Photon States in Atomic Ensembles Alexey Gorshkov, Axel Andre, Michael Fleischhauer, Anders Sorensen, Mikhail Lukin We describe an optimal control strategy for storage and retrieval of a photon wavepacket of a given shape in a radiatively broadened $\Lambda$type atomic medium with a given optical depth (OD). The control is provided by an appropriately shaped classical laser field. We present a universal theoretical framework for analyzing various approaches to pulse storage ranging from adiabatic reduction of photon pulse group velocity and pulse propagation control via offresonant Raman fields to photonecho based approaches. We show that when properly optimized these three approaches yield identical efficiency. We extend our model to include Doppler broadening and, in particular, show that at high enough OD Doppler broadening is irrelevant. [Preview Abstract] 

W1.00025: Investigation of lasing from dye doped plastics using flash lamp and Nd:YAG excitation. Mark Masters, Mike De Armond, Clint Reynolds, Hans Suedhoff We present an investigation of organic dye doped plastics as a lasing medium. The host materials examined are poly(methyl methacrylate) [acrylic], epoxy, polyester and polyurethane. Various solvents are used to improve dye dispersion within the material. Two forms of excitation (flash lamp and frequency doubled Nd:YAG) are used. For the Nd:YAG pumped dye lasers, a disk of dye doped plastic is mounted in a housing to provide random orbital motion. The disk is within a Littmann configuration cavity. Each dye disk is tested for threshold, durability, power output, bandwidth, and tuning range. An end pumped cylinder is also explored. For the flash lamp pumped dye lasers two configurations are used: a traditional dye cylinder within an elliptical reflector and a hollow cylinder with the flash lamp within the hollow. A monolithic cavity for the flash lamp pumped system is investigated. [Preview Abstract] 

W1.00026: Observation of Electromagnetically Induced Transparency and Dark Fluorescence in a Lithium Molecule Jianbing Qi, A. Marjatta Lyyra We observed the electromagnetically induced transparency and dark fluorescence in a Lithium molecule. We used density matrix methods to simulate the response of an open molecular threelevel system to the action of a strong coupling field and a week probe. The analytical solutions obtained under the steady state condition are in excellent agreement with the experimental spectra. We show that the coherence is remarkably preserved even when the coupling field was detuned far from the resonance transition. [Preview Abstract] 

W1.00027: Toward Nonlinear Optics with Confined Photons and Atoms Vlatko Balic, Michal Bajcsy, Alexander S. Zibrov, Vladan Vuletic, Mikhail D. Lukin Cold atoms trapped inside a hollow core photonic bandgap fiber create medium with unique optical properties, such as large optical depth and long coherence times. Furthermore, the fiber itself guides the interacting light in tight spatial confinement over distances not limited by diffraction and dramatically increases electric field intensity. Optical nonlinearities achievable under these conditions can be potentially used for coherent nonlinear interactions between single photon light pulses. In this work we present an atom cooling and trapping setup that loads cold Rb atoms into a dipole trap localized within the hollow core of the fiber and we study properties of the cold Rb atoms confined in the fiber. [Preview Abstract] 

W1.00028: Optical coupling and parametric sideband generation in a semiconductor bound exciton Renuka Rajapakse, Susanne Yelin Group theoretical techniques are used to deduce the selection rules and energy splitting of the electric dipole absorption lines $\Gamma_6\rightarrow\Gamma_8$, $\Gamma_7 \rightarrow\Gamma_8$ of a donor exciton in a tetrahedral semiconductor, e.g., GaAs. We obtain selection rules for the above transitions for the spin states $\Delta m_j$. The application in a bound exciton system in a magnetic field for the purposes of obtaining electromagnetically induced transparency is discussed. In particular, Stokes and Anti Stokes couplings have been experimentally observed in such a system. We theoretically calculate the expected gains of the Stokes and anti Stokes couplings for $\sigma$ and $\pi$ polarization of the pump field. We show that the system can be interpreted as one exhibiting double $\Lambda$type transitions, and therefore could be used for coherent nonlinear optics and, ultimately, quantumoptics based quantum information processing. [Preview Abstract] 

W1.00029: Darkstate polariton collapses and revivals Odell Collins, Stewart Jenkins, Dzmitry Matsukevich, Thierry Chaneliere, ShauYu Lan, Alex Kuzmich, T.A. Brian Kennedy We investigate the dynamics of darkstate polaritons in an atomic ensemble with groundstate degeneracy. A signal light pulse may be stored and retrieved from the atomic sample by adiabatic variation of the amplitude of a control field. During the storage process, a magnetic field causes a rotation of the atomic hyperfine coherences, leading to collapses and revivals of the darkstate polariton number. These collapses and revivals are observed in measurements of the retrieved signal field, as a function of storage time and magnetic field orientation. We explain the observed reduction of revival amplitudes by accounting for magnetic field gradients within the atomic sample. [Preview Abstract] 

W1.00030: DiffusionInduced Ramsey Narrowing Yanhong Xiao, Irina Novikova, David Phillips, Ronald Walsworth Diffusioninduced Ramsey narrowing is a general phenomenon in which diffusion of coherence in and out of an interaction region such as a laser beam induces spectral narrowing of the associated resonance line shape. We will present an intuitive analytical model, detailed numerical calculations, and experiments illustrative of this spectral narrowing effect. Diffusioninduced Ramsey narrowing occurs commonly in optically interrogated atomic systems and may also be relevant to quantum dots and other solidstate spin systems. [Preview Abstract] 

W1.00031: EIT spectra in coated cells Mason Klein, Michael Hohensee, David Phillips, Irina Novikova, Ronald Walsworth We use rubidium vapor cells with paraffincoated walls, which greatly reduce the ground state decoherence rate due to wall collisions, to measure electromagneticallyinduced transparency (EIT) spectra. Characteristic line shapes have a dual structure, with a wide feature corresponding to the transit timescale and an ultranarrow feature corresponding to the coherence lifetime allowed by the coating. Such narrow features can exhibit large contrast, and so are of interest to slow light studies. Using a model based on Ramsey pulse sequences, we can explain qualitative behavior for both Zeeman and hyperfine EIT, with good line width agreement in the Zeeman case in the small beam limit. [Preview Abstract] 

W1.00032: Slow light propagation in coated cells Michael Hohensee, Mason Klein, David Phillips, Irina Novikova, Ronald Walsworth Rubidium vapor cells with walls coated with paraffins such as tetracontane can have very long coherence times due to the suppression of decoherence during wall collisions by the coating. Here we report on the use of such cells (with an intrinsic coherence time of groundstate hyperfine and Zeeman transitions longer than 10 ms) for slow and stored light. Guided by our static Ramseynarrowing EIT model and recent dynamical simulations, we improve upon past results in terms of fractional pulse delay and storage efficiency. [Preview Abstract] 

W1.00033: EIT noise spectroscopy with a broadband laser Yanhong Xiao, David Phillips, Cindy Hancox, Irina Novikova, Ronald Walsworth Laser PMAM noise conversion is of great interest in atomic clocks based on coherent population trapping (CPT) and the related process of electromagnetically induced transparency (EIT). We report a study of the role of EIT ground state coherence on the intensitynoise spectrum using a broadband laser such as a VCSEL. We also discuss possibilities of extending the result to photon statistics. [Preview Abstract] 

W1.00034: Experimental study of light storage in Rb vapor Irina Novikova, Jeronimo Maze, David Phillips, Ronald Walsworth We study the propagation and storage of weak optical pulses in warm Rb vapor under conditions of electromagnetically induced transparency (EIT). We investigate the effects of various experimental parameters (such as buffer gas pressure, atomic density, etc.) on storage time and fidelity. [Preview Abstract] 

W1.00035: Fluorescence spectrum of spontaneous emission in cavity. Matthew Terraciano, Rebecca Olson, Luis Orozco, Perry Rice We study the probe spectrum of light generated by spontaneous emission into the mode of a cavity QED system. We identify the spontaneous emission process by the polarization of the transmitted light when the excitation of the atoms is with linear polarization in a $\Delta m=0$ transition in the $D_2$ line of $^{85}$Rb. The probe spectrum has a maximum onresonance when the number of inverted atoms for an input drive is maximal. For a larger number of atoms N, the maximum splits and develops into a doublet, but its frequencies are different from those of the socalled vacuum Rabi splitting. [Preview Abstract] 

W1.00036: AtomField Entanglement in a Cavity QED System Perry Rice, James Clemens, Nick Cummings, Luis Orozco We consider the entanglement in a cavity QED system as a function of driving field strength via the entanglement of formation and the logarithmic negativity. There is an optimal field strength for generating entanglement, around the saturation intensity. When the atoms become saturated, the system tends towards a product state where the field is in a coherent state. We also consider conditioned homodyne and conditioned photo as entanglement witnesses. Further we consider the time development of entanglement, and the amount of information about entanglement contained in time dependent cross correlation functions. [Preview Abstract] 

W1.00037: Casimir force in a cylinderplane configuration Michael BrownHayes, Scott Middleman, WooJoong Kim, Diego Dalvit, Francisco Mazzitelli, Roberto Onofrio We have developed and tested an apparatus [1] to measure the Casimir force in a cylinderplane configuration, which is a compromise between the parallel plane and sphereplane configurations, with intermediate advantages. Preliminary calibrations with electrostatic forces show that the Casimir forces should be detectable in a range large enough to observe the expected thermal corrections. \newline \newline [1] M. BrownHayes, D.A.R. Dalvit, F.D. Mazzitelli, W.J. Kim, and R. Onofrio, Phys. Rev. A 72, 052102 (2005). [Preview Abstract] 

W1.00038: Quantum optics with surface plasmons: engineering strong coupling and efficient singlephoton generation Darrick Chang, Anders Sorensen, Philip Hemmer, Aryesh Mukherjee, Gurudev Dutt, Mikhail Lukin We propose a method that enables strong, coherent coupling between individual optical emitters and electromagnetic excitations in conducting nanostructures. The excitations are guided optical plasmons that can be localized to subwavelength dimensions. The subwavelength confinement and small mode volumes associated with these plasmons lead to strong coupling with nearby emitters. We show that under realistic conditions, this coupling causes optical emission to be almost entirely directed into the plasmon modes via a mechanism analogous to the Purcell effect in cavity quantum electrodynamics. We first illustrate this result for the case of a nanowire, before considering the optimized geometry of a nanotip. We describe an application of this technique involving efficient singlephoton generation on demand, in which the plasmons are efficiently outcoupled to a dielectric waveguide. Finally, we discuss a preliminary experiment to probe and observe the strong coupling regime between a silver nanowire and quantum dot. [Preview Abstract] 

W1.00039: Barium Ion Trap Cavity QED Adam Steele, Layne Churchill, Paul Griffin, Michael Chapman We report our progress toward the development of a scalable trapped ion and optical cavity system. Due to their long confinement times and the relative ease in trapping them individually, atomic ions remain an excellent candidate for tomorrow's qubit memories. The optical cavity system will provide the coherent coupling between single cavity photons and single trapped ions required to efficiently exchange quantum information between distant ion qubits. Combining atombased quantum memories with photonbased quantum communication channels offers a compelling architecture for a quantum information network. [Preview Abstract] 

W1.00040: Spectroscopy and coherent control of single nitrogenvacancy (NV) centers M. V. Gurudev Dutt, Lilian Childress, Philip Hemmer, Alexander Zibrov, Fedor Jelezko, Mikhail Lukin The nitrogen vacancy (NV) center in diamond has received considerable attention in recent years because it offers the opportunity to coherently manipulate the spin and electronic transitions of a single quantum system in the solid state. We describe optical spectroscopic measurements of single NV centers at low temperatures, via resonant excitation within the zerophonon line, and observations of extremely sharp ($\sim $ 50  100 MHz), stable spectral lines. We have also carried out experiments to measure the fine structure, determine the optical transition strengths, and perform coherent control on single NV centers. In particular, optically detected single spin Rabi nutations and Hahn echoes show long coherence times and coherent coupling to nuclear spins even at room temperature. NV centers represent a promising candidate for implementation of a recently proposed scheme for long distance communication. Experimental progress toward implementation of these ideas will be presented. [Preview Abstract] 

W1.00041: Sudden switching in twostate systems Kh. Shakov, J.H. McGuire, L. Kaplan, A. Chalastaras, D. Uskov Analytic solutions are developed for twostate systems strongly perturbed by a series of rapidly changing pulses, called 'kicks'. The evolution matrix may be expressed as a time orrdered product of evolution matricies for single kicks. Single, double and triple kicks are explicitly considered, and the onset of time ordering is examined. The effects of different order of kicks on the dynamics of the system is studied and commpared with effects of time ordering in general. To determine the range of validity of this apporach, the effect of using pulses of finite widths for 2s  2p transitions in atomic hydrogen is examined numerically. [Preview Abstract] 

W1.00042: Noise Induced Decoherence of Rydberg Atoms in a DC Field S. Yoshida, J. Burgd\"orfer, C.O. Reinhold, W. Zhao, J.J. Mestayer, J.C. Lancaster, F.B. Dunning Application of a sudden field step to a Rydberg atom leads to creation of a Stark wavepacket whose evolution can be monitored using a halfcycle probe pulse applied after a variable time delay. We analyze the effects of noise on such wavepackets that is generated by quasirandomly modulating the amplitude of the dc field. This noise induces decoherence which is manifested as a damping of the Stark quantum beats. We discuss the effects of different types of noise and present calculations and measurements for K(350p) atoms and ``colored'' noise, i.e., noise with a nonuniform power spectrum that possesses a characteristic frequency. We show that damping is most rapid when this frequency matches the orbital frequency of the Rydberg electron. [Preview Abstract] 

W1.00043: Navigating in Phase Space Wei Zhao, Jeff Mestayer, Jim Lancaster, F. Barry Dunning, Carlos Reinhold, Shuhei Yoshida, Joachim Burgdorfer A Rydberg atom subject to a periodic train of unidirectional electric field pulses, termed halfcycle pulses (HCPs), of duration much less than the classical electron orbital period, is a ``kicked'' quantum system whose classical counterpart displays ``soft'' chaos, i.e., a mixture of regular and chaotic dynamics. Poincar\'{e} surfaces of section for the kicked atom contain a number of stable islands enclosed by KAM tori that are embedded in a chaotic sea. We show how different dynamical behaviors are observed if an initial state that is transiently localized in phase space is placed in different regions of large islands immediately before the train. If the initial state is localized at the center of the island little evolution of the excitedstate distribution is observed during the HCP train. In contrast, placing the initial state in an outer region leads to periodic changes in this distribution that are associated with motion on the KAM tori. This work points to the feasibility of manipulating atomic states by navigating in phase space. Research supported by NSF, DoE, the R. A. Welch Foundation, and the FWF (Austria). [Preview Abstract] 

W1.00044: Probing the momenta of Stark eigenstates J. MurrayKrezan, R. R. Jones Approximate momentum distributions of Rydberg electrons in static electric fields have been obtained using an improved Impulse Momentum Retrieval (IMR)technique. An imaging detector enables the measurement of halfcycle pulse (HCP) ionization probability across the spatial profile of a focused HCP beam. By modulating the HCP amplitude [Zeibel and Jones, Phys. Rev. A \textbf{68}, 023410 (2003)], we directly measure the derivative of the ionization vs. HCP impulse curve, enabling the recovery of momentum distributions with finer resolution than previously attainable. For example, for Stark states with nearly zero dipole moments, we observe a notch in the projection of the momentum distribution along the Stark field axis. We have developed a semiclassical method for simulating the effect that the finite HCP duration has on our measurements. Reasonable agreeement between simulated and measured momentum distributions is obtained. This work has been supported by the AFOSR and the NSF. [Preview Abstract] 

W1.00045: Measurements of rotation wave packets for molecular phase modulation Mark Baertschy, Omid Masihzadeh, Klaus Hartinger, Randy Bartels In recent years molecular phase modulation of light has been vigorously investigated as a method for optical pulse manipulation. We characterize rotational wave packets formed by intense laser pulses using the transient index of refraction. In particular, we are looking to find optimal conditions for spectral modulation of a probe pulse. Maximizing spectral modulation requires exciting wave packets with coherences between high angular momenta. [Preview Abstract] 

W1.00046: Chaotic Escape of Specularly Reflecting Rays From a Vaseshaped Cavity Jaison Novick, John Delos, Kevin Mitchell We study the escape of rays from a two dimensional, specularly reflecting open cavity having the shape of a vase. At the narrowest point of the neck of the vase there is an unstable periodic orbit which defines a dividing surface between rays that escape and rays that are turned back into the cavity. We imagine a point source on the cavity wall emitting rays in all directions and we record the time to reach a detector forming the mouth of the vase. We find that the rays arrive at the detector in pulses. The escape time, as a function of the initial conditions, displays a weak selfsimilarity which is understood upon transformation to a suitable phase space. Here, we find that the selfsimilarity arises from the intersection of the initial conditions with a homoclinic tangle, which is formed by the intersections of stable and unstable manifolds emanating from the unstable periodic orbit. We present a topological theory that partially predicts the selfsimilarity. We conclude with an example comparing the predictions to numerical calculations. [Preview Abstract] 

W1.00047: FUNDAMENTAL SYMMETRIES AND PRECISION MEASUREMENTS 

W1.00048: Laboratory Observability of a Cosmologically Changing Light Speed Felix T. Smith Einstein's axiom of special relativity was not an invariant light speed, but less restrictive: The velocity of light is independent of the motion of the light source. This is compatible with an expanding hyperbolic position space tangent to Minkowski fourspace [1]. In this geometry $c$ decreases as $t^{1/2}$ and a new HubbleLorentz expansion constant appears, $\sigma =c_0 ^2H_0 ^{1}=3.89\times 10^{34}$ m$^2$s^{1}$. The practical choice of $c$ as a defined constant is then not relativistically invariant, and should be modified. The logarithmic rate of change of $c$ is directly connected with the Hubble parameter, $d\ln c/dt=H\left( t \right)/2$, with the present value $3.65\times 10^{11}\mbox{ y}^{1}$. In 1972 $c$ was measured to 3.5 parts in $10^9$. If this precision can now be improved by 10 or 100, the predicted rate of change of $c$ can be tested. The issues involved in converting between cosmological and laboratory time and distance scales will be reported. Ultimately, a laboratory measurement of $H_0 $ may be in prospect. \newline \newline [1] F. T. Smith, Ann. Fond. L. de Broglie, \textbf{30}, 179 (2005); http://www.ensmp.fr/aflb/AFLB302/table302.htm [Preview Abstract] 

W1.00049: The Fundamental Constants if $c$ is Changing: A New Mass Constant and its Connection with the Electron Felix T. Smith When special relativity is extended to expanding hyperbolic position space [1], $c$ decreases as $t^{1/2}$ and there is a new expansion constant, $\sigma =c_0 ^2H_0 ^{1}=3.89\times 10^{34}$ m$^2$s^{1}$. Many fundamental constants become timedependent and must be corrected by a small power of $c$. The corrected electrical permittivity of space is $\bar {\varepsilon }_{o} =\varepsilon_o c$, and $\alpha $ remains constant. The corrected gravitation constant is $\bar {G}=G/c$. A new fundamental mass constant of gravitation and cosmology occurs, $m_\ast =\left( {\hbar ^2/\bar {G}\sigma } \right)^{1/3}=\left( {\hbar ^2H_0 /G_0 c_0 } \right)^{1/3}$, with the value $1.087\left( {\pm 0.010} \right)\times 10^{28}\mbox{ kg}$. Its product $\alpha m_\ast $ with $\alpha $ accounts for 87{\%} of the observed inertial mass $m_e $ of the electron. This establishes a new phenomenological relationship between the constants of electromagnetism and the electron on the one hand and those of gravitation and cosmology on the other. \newline [1] F. T. Smith, Ann. Fond. L. de Broglie, \textbf{30}, 179 (2005); ); http://www.ensmp.fr/aflb/AFLB302/table302.htm [Preview Abstract] 

W1.00050: Atomic structure measurements and tests of fundamental symmetries in a thallium atomic beam Protik Majumder, David Butts, Ralph Uhl Using a thallium atomic beam apparatus, we are undertaking a series of laser spectroscopy measurements with the goal of providing precise, independent crosschecks on the accuracy of new calculations of parity nonconservation in thallium, as well as probing possible new symmetryviolating forces. In our apparatus, a diode laser beam interacts transversely with a dense, thallium beam and reveals roughly tenfold Doppler narrowing of the absorption profile. Having completed a new 0.4\% measurement of the Stark shift in the 378 nm E1 transition in thallium, we are now studying the M1/E2 1283\,nm $6P_{1/2}6P_{3/2}$ transition in the atomic beam. To enhance the detectability of this weak transition, we are utilizing both a twotone frequency modulation method, as well as an entirely new scheme to measure differential optical cavity phase shifts induced by the atoms. In the course of this work, we have developed a new laser stabilization method suitable for locking near this E1forbidden transition. We use lowfield Faraday rotation polarimetry and achieve subMHz frequency stability. Future work includes twostep atomic beam excitation and Stark shift experiments in thallium, as well as a search for longrange Todd, Peven symmetryviolating forces in thallium. Current results will be presented. [Preview Abstract] 

W1.00051: Is the photon recoil equal to the photon momentum? Kurt Gibble It is well known that an isolated atom recoils with the momentum of the photon when it absorbs a photon from an infinite plane wave. When the transverse electromagnetic field has a finite extent, the photon wave vector in the longitudinal direction is smaller. When an isolated atom absorbs a photon from a finite laser beam, is the atomic recoil smaller than that for an infinite plane wave? We show that it is smaller and it has a peculiar dependence on the transverse variation of the field. For atom interferometers that measure the photonrecoil, the difference in the size of the photon recoil is safely below the current measurement accuracy for the laser beams that are used. A related problem is the photonrecoil frequencyshift for microwave atomic clocks. For a cesium clock, the usual photonrecoil frequency shift of h$^{2}$k$^{2}$/2m gives a fractional frequency shift of 1.5$\times $10$^{16}$, which is not far below the accuracy of current clocks. We show that the frequency shift does not have the usual form and has a similar behavior as for the transverse field variations above. It depends in unusual ways on the interrogation time, and the size of the atomic wavefunction at the first interaction. [Preview Abstract] 

W1.00052: Progress toward improved Lorentz symmetry tests with H and noble gas masers Yulia Gurevich, Alex Glenday, David Phillips, Ronald Walsworth Measurements using atomic clocks can be sensitive to violations of Lorentz and CPT symmetry through differential frequency changes as the direction or velocity of the clocks change with respect to an inertial frame. We will present the status of experiments underway utilizing atomic hydrogen masers and the twospecies noble gas masers which will improve constraints on potential Lorentz and CPT violations in the proton and neutron respectively. [Preview Abstract] 

W1.00053: Demonstration of an Electron Electric Dipole Moment Experiment Using ElectricField Quantization in a Cesium Cold Atom Fountain Harvey Gould, Jason M. Amini, Charles T. Munger A Cs fountain electron electric dipole moment (EDM) experiment using electricfield quantization is demonstrated. With magnetic fields reduced to $\le$ 200 pT, the electric field lifts the degeneracy between hyperfine $m_F$ levels and, along with the fountain geometry, suppresses systematics from motional magnetic fields. Transitions are induced and the atoms polarized and analyzed in fieldfree regions. Our results suggest that a fountain experiment can detect (or rule out) an electron EDM far smaller than the present experimental limits. [Preview Abstract] 

W1.00054: Estimation of One and TwoPhoton Rydberg Transition Rates in Helium Driven Directly by an Optical Frequency Comb D.E. Procyk, E.E. Eyler, R.J. Jones, K.D. Moll, M.J. Thorpe, J. Ye Direct frequency comb spectroscopy (DFCS) involves the resonant excitation of atoms or molecules directly with one or multiple components of an optical frequency comb, allowing high resolution spectroscopy and absolute frequency measurements across a wide spectral bandwidth. While DFCS has been proven with alkali atoms, extension of the technique to atomic helium will lead to precision measurements of this important atom. For helium atoms formed in a metastable helium MOT at milliKelvin temperatures we have estimated transition rates for excitation by a frequency comb, using a quantum defect model with scaled oscillator strengths. In the triplet system, Rydberg $n^3D \leftarrow $2$^3S$ and $n^3S \leftarrow $2$^3S$ transitions can be excited by resonant or nearresonant twophoton excitation via the intermediate 3$^3P$ state. The rates are highly favorable, $>10^6$ s$^{1}$ per atom even for $n \approx 40$. The 1$^1S$ ground state could also be studied by ``dumping" metastable atoms from the MOT using an additional laser. Although the twophoton 2$^1S \leftarrow $1$^1S$ transition presently looks unfeasible, rates for onephoton $n^1P \leftarrow $1$^1S$ transitions driven by a farUV comb are reasonable. [Preview Abstract] 

W1.00055: An Overview of the Search for the Electron Electric Dipole Moment Using Trapped Molecular Ions Laura Sinclair, John Bohn, Aaron Leanhardt, Edmund Meyer, Russell Stutz, Eric Cornell The current limit on the electron electric dipole moment ($d_{e} < 1.6 * 10^{27}$ e*cm) was set using an atomic beam of Tl \footnotemark. We have proposed the use of supersonically cooled molecular ions in an RF trap to improve this limit. This experiment should benefit from the large effective electric fields experienced by an electron in polarized molecules and the long spin coherence time of trapped ions. We will outline the motivation behind the two current candidate ions, HfH$^{+}$ and PtH$^{+}$. Recent experimental progress will also be discussed. \footnotetext[1]{B.C. Regan et. al., Phys. Rev. Lett. 88, 718051 (2002).} [Preview Abstract] 

W1.00056: Precision mass measurement using two ions in a Penning trap Matthew Redshaw, Joseph McDaniel, Thomas DeVore, Elizabeth Wingfield, Wei Shi, Edmund Myers We have implemented a technique for precision mass comparison of two ions simultaneously trapped in a Penning trap in which each ion is alternately positioned at the center of the trap  where its cyclotron frequency is measured  or else parked in a large cyclotron orbit. Using the method to compare $^{28}$SiH$_{3}^{+}$/$^{31}$P$^{+}$ we have obtained a new atomic mass for $^{31}$P of 30.973 761 999 7(61) u. We have also used the method to observe shifts in the cyclotron frequency of the molecular ions CO$^{+}$ and PH$^{+}$ due to the interaction between the ion's polarizability and the motional electric field. Progress towards a) implementing \textit{simultaneous} cyclotron frequency comparisons using two ions in a coupled magnetron orbit, b) a precision measurement of the mass difference between $^{3}$T and $^{3}$He, c) the use of polarizability shifts for single ion molecular spectroscopy, and d) a precision mass measurement of $^{40}$Ca will also be reported. [Preview Abstract] 

W1.00057: Progress on single trapped indium and barium ion optical frequency standards using all solidstate light sources Jeff Sherman, William Trimble, Amar Andalkar, Pete Morcos, Warren Nagourney, Norval Fortson Single trapped ions cooled to the LambDicke regime are spectroscopic systems free of many external perturbations and are therefore attractive as optical frequency standards. We report continued development of single indium ion and barium ion rf PaulStraubel traps and laser cooling systems. The forbidden ${^1}S_0 \leftrightarrow {^3}P_0$ transition in In$^+$ at 237 nm has a quality factor of $10^{15}$ and is immune to $\sim 1$ Hz quadratic Stark shifts that can limit other systems. In addition, the extraordinarily long $5D_{3/2}$ lifetime ($\tau \sim 80$~s) in a single trapped barium ion yields an electric dipole forbidden 2051 nm $6S_{1/2} \leftrightarrow 5D_{3/2}$ transition with a quality factor of $10^{16}$. Further, the odd isotope $^{137}$Ba$^+$ (I = 3/2) has an excited state with total angular momentum $F' = 0$ so an optical frequency standard based on this transition also avoids significant quadratic Stark shifts. We present our latest experimental probes of these transitions using new low linewidth diode pumped solid state laser systems (a frequency quadrupled nonplanar ring oscillator Nd:YAG at 946 nm and a diode pumped Tm,Ho:YLF at 2 $\mu$m), new stable reference cavities, and propose a laboratory constraint on fundamental constant drift. [Preview Abstract] 

W1.00058: Development of a compact atomic comagnetometer G. Vasilakis, T.W. Kornack, R.K. Ghosh, S.J. Smullin, M.V. Romalis We have developed a highsensitivity atomic comagnetometer for tests of Lorentz and CPT symmetries. It also may be used as a gyroscope. Optical pumping of a highdensity alkali metal vapor creates a spinexchange relaxation free (SERF) magnetometer. The noble gas atoms in the cell are polarized by the alkali atoms. With an appropriate applied field, the polarized noble gas atoms cancel transverse magnetic fields, leaving the system sensitive only to nonmagnetic spin interactions and rotation. We have performed a test of CPT and Lorentz symmetries by looking for a sidereal signal in the lab frame. To avoid long term drift, we are designing a small version of the magnetometer on a rotary platform. The smaller system will be more sensitive to the Johnson noise generated by thermal currents in the magnetic shields. In order to reduce this noise, we will use ferrite, rather than mumetal, for the innermost layer of magnetic shielding. It is expected that sensitivity will also be increased by enclosing the optics in a vacuum chamber and using $^{21}$Ne instead of $^3$He as the noble gas. [Preview Abstract] 

W1.00059: Progress towards an improved search for a permanent EDM of Hg atoms W. C. Griffith, M. D. Swallows, B. R. Heckel, E. N. Fortson, M. V. Romalis The measurement of a finite permanent electric dipole moment (EDM) on any atom or particle would reveal a new source of CP violation outside of the Standard Model. At present, the tightest bound on any EDM comes from our measurement with $^{199}$Hg atoms, which set an upper limit of $d < 2.1 \times 10^{28} \,e\,{\rm cm}$ [1]. In that work, a comparison was made of the spin precession frequencies in two $^{199}$Hg vapor cells placed in a common magnetic field and oppositely directed electric fields. The signature of an EDM would be a frequency shift correlated with the electric field direction. The present version of the experiment uses a stack of four vapor cells. The two additional cells are at zero electric field and are used as magnetometers to help reduce magnetic field gradient noise and to help diagnose magnetic systematic effects. Initial data taken with the four cell apparatus would often show electric field correlated magnetic field shifts. These effects were possibly due to HV discharges orienting trace ferromagnetic impurities, and the replacement of some materials near the vapor cells and an improved cleaning procedure have greatly reduced their occurrence. We expect to report data with at least a factor of two improvement in statistical sensitivity over our previous result. [1] M.V. Romalis, W.C. Griffith, J.P. Jacobs, and E.N. Fortson, Phys. Rev. Lett. {\bf 86}, 2505 (2001). [Preview Abstract] 

W1.00060: ThreePhoton EITA for Observing the $^{1}$S$_{0} \rightarrow\,^{3}$P$_{0}$ Clock Transition in Atomic Yb Amar Andalkar, Eryn Cook, Tao Hong, Anna Markhotok, Warren Nagourney, Norval Fortson Recent experiments have observed the $^{1}$S$_{0} \rightarrow\,^{3}$P$_{0}$ clock transition in odd isotopes of atomic Yb, where the transition is weakly allowed through internal hyperfine coupling. We report on progress towards an observation of this transition in the even isotopes, which offer the advantage of a narrower clock transition in which the energy interval is not affected by external magnetic fields or light polarization. While the singlephoton transition is strictly forbidden in this case, threephoton electromagnetically induced transparency and absorption (EITA) can be used to produce a sharp resonance line. With this method, the width and rate of the clock transition can, in principle, be continuously adjusted from the MHz level to submHz without loss of signal amplitude by varying the intensities of the three light fields. Doppler and recoil effects can be eliminated by proper alignment of the three optical beams. Theoretical calculations have shown that sharp Dopplerfree EITA features can be expected on the threephoton clock transition and also on a simpler threephoton scheme using the $^{1}$S$_{0} \rightarrow\,^{1}$P$_{1}$ (399~nm) and $^{1}$S$_ {0} \rightarrow\,^{3}$P$_{1}$ (556~nm) transitions. Experimental work is underway to test this arrangement, with eventual application to the clock transition via the 556~nm, 680~nm, and 649~nm transitions involving the $^{1}$S$_{0}$, $^{3}$P$_{1}$, $^{3}$S$_{1}$, and $^{3}$P$_{0}$ states. [Preview Abstract] 

W1.00061: Some Investigations with Fiber Coupled Laser Diode Modules for Use in Precision Spectroscopy Ali Khademian, Koustubh Danekar, Krista Jansen, David Shiner Mass produced commercial fibercoupled pump laser diodes are particularly attractive laser sources because of their relatively high power (200500 mW) and low cost compared to other laser systems. We incorporate narrow bandwidth fiber Bragg gratings (FBG) to form an external cavity using these singlemode fibercoupled pump lasers at 960980 nm and 1420 1500 nm. The lasers normally operate in many longitudinal modes. Under appropriate conditions single frequency operation results with small tuning about the FBG center wavelength. We also discuss our use of a common diode laser model that characterizes the laser operation, along with some simple measurements to help fix the model parameters. In our particular application (1S to 2S transition in the atomic hydrogen isotopes), we need an ultra violet 243 nm laser source. Frequency doubling of a stabilized laser at 972 nm can be achieved using nonlinear crystals. Results of employing PPLN and PPKTP waveguides and PPKTP in a self contained resonant buildup cavity to generate blue laser at 486 nm are presented. [Preview Abstract] 

W1.00062: Novel Scheme to Measure the Electric Dipole Moment of the Electron Using PbO Yong Jiang The unveiling of an electron electric dipole moment (EDM d$_{e})$ within the next few orders of magnitude beyond the current limit of $\vert $d$_{e}\vert <$1.6x10$^{27}$ ecm would be of great interest in the fundamental physics as an evidence for physics beyond the standard model. An experiment to look for EDM of the electron using the metastable a(1) ($^{3}\Sigma )$ state of PbO molecule is being implemented. High level of sensitivity would be achievable because of the extreme polarizability of diatomic molecules with a vapor cell. Here we would explore a novel scheme of signal detection using microwave absorption. Based on the nowadays available technology and experiment setup, we estimated microwave absorption crosssection, signal size and noise feature of the system. We also report the state preparation result using microwave technique as demonstration. [Preview Abstract] 

W1.00063: STRONG LASER FIELD PROCESSES 

W1.00064: Precision calculation of intenselaserfield multiphoton ionization (MPI) rates of {H}$_2^+$ at critical internuclear distances SangKil Son, ShihI Chu We extend the timeindependent nonHermitian Floquet formalism [1] for high precision calculation of the MPI rates of {H}$_2^+$ at internuclear distances ($R$) from 2.0 to 20.0 a.u.\ in intense laser fields with intensity $1 \times 10^{14}$ W/cm$^2$ and wavelength 791 nm. The procedure involves the use of the complexscaling generalized pseudospectral (CSGPS) method for \textit{nonuniform} spatial discretization of the Hamiltonian expressed in prolate spheroidal coordinates. We found that the MPI rates strongly depend upon $R$ and are significantly enhanced at several critical distances ($R \sim $~8, 11, and 15 a.u.) in good agreement with the recent experimental results [2]. [1] S.~I.~Chu and D.~A.~Telnov, Phys.\ Rep.\ \textbf{390}, 1 (2004). [2] D.~Pavi{\v c}i{\'c}, A.~Kiess, T.~W.~H{\"a}nsch, and H.~Figger, Phys.\ Rev.\ Lett.\ \textbf{94}, 163002 (2005). [Preview Abstract] 

W1.00065: Application of Coulomb Wave Function DVR to Atomic Systems in Strong Laser Fields LiangYou Peng, Anthony F. Starace We present an efficient and accurate grid method for solving the timedependent Schr\"odinger equation (TDSE) for atomic systems interacting with short laser pulses. The radial part of the wave function is expanded in a DVR (Discrete Variable Representation) basis constructed from the positive energy Coulomb wave function. The time propagation of the wave function is implemented using the wellknown Arnoldi method. Compared with the usual finite difference (FD) discretization scheme for the radial coordinate, this method requires fewer grid points and handles naturally the Coulomb singularity at the origin. As examples, the method is shown to give accurate ionization rates for both H and H$^$ over a wide range of laser parameters. [Preview Abstract] 

W1.00066: Parametrization of the Transition Amplitude and the TriplyDifferential Cross Section for TwoPhoton Double Ionization E.A. Pronin, Andrei Y. Istomin, Anthony F. Starace, N.L. Manakov, S.I. Marmo We present modelindependent representations for the transition amplitude and the triplydifferential cross section for twophoton double ionization (TPDI) of He, in which the kinematical and dynamical parameters of the process are separated. For the case of DPI by two photons having different polarizations, the transition amplitude is parametrized by {\it five} polarizationindependent amplitudes, which can be expressed in terms of exact twoelectron radial matrix elements. For the case of TPDI by two identical photons, only {\it four} amplitudes are necessary. For this latter case we analyze photon polarization effects and predict the existence of both circular dichroism (CD) and elliptic dichroism (ED) effects in TPDI electron angular distributions. This contrasts with singlephoton double ionization, in which only the CD effect exists. We also analyze the dynamics of the TPDI process within the lowestorder perturbation theory in the interelectron interaction and estimate the magnitudes of these effects. [Preview Abstract] 

W1.00067: Lowfrequency Bremsstrahlung for the Critical Geometry N.L. Manakov, A.A. Krylovetsky, S.I. Marmo, Anthony F. Starace The discrepancy between the experimental [1] and theoretical [2,3] results for the critical geometry, i.e., when $({\bf e} \cdot\Delta{\bf p})=0$ (where ${\bf e}$ and $\Delta{\bf p}$ are the polarization vector and the transferred electron momentum), is analyzed for examples of onephoton and twophoton low frequency Bremsstrahlung (BrS) in a Coulomb field. For this geometry, the wellknown KrollWatson approximation yields a zero BrS cross section while no significant decrease of the BrS radiation intensity is observed in experiments [1]. We present an analytical expression for the lowfrequency cross sections for one and twophoton stimulated BrS for the $({\bf e} \cdot\Delta{\bf p})\approx 0$  region and find them to be small (of the order of $x^2\ln^2{x}$, where $ x=m\hbar\omega/p^2$ for the onephoton case) as compared to the cross section outside the critical geometry region. Thus our results are in accordance with those in Refs. [2,3] and disagree with Ref. [1]. [1] B. Walbank and J.K. Holmes, Phys. Rev. A {\bf 48}, R2515 (1993); [2] K.M. Dunseath and M. TeraoDunseath, J. Phys. B {\bf 37}, 1305 (2004); [3] S. Hokland and L.B. Madsen, Eur. Phys. J. D {\bf 29}, 209 (2004). [Preview Abstract] 

W1.00068: Twophoton abovethreshold ionization of atoms N.L. Manakov, S.I. Marmo, S.A. Sviridov Twophoton ionization of alkali atoms by laser photons with abovethreshold energies $(\hbar\omega > E_0)$ is investigated. We use the Fues model potential (FMP) for an optical electron and Sturmian expansion for the FMP Green function. The convergence of Sturmian series for radial matrix elements of twophoton boundfree transitions is achieved by using the $\epsilon$algorithm (a numerical version of Pade approximation). Such an approach allows one to calculate above threshold ionization crosssections over a wide range of photon energies above the threshold. The accuracy of numerical calculations is controlled by an independent calculation for the amplitude of stepwise transitions to the continuum (which are determined by the imaginary part of the FMP Green function) and by an analytical study of the ``lowfrequency'' (nearthreshold) limit. Similar calculations are performed also for rare gas atoms. [Preview Abstract] 

W1.00069: Negative molecular ion in a strong DC field S. Borzunov, M.V. Frolov, N.L. Manakov, Anthony F. Starace We study the simplest model of a negative molecular ion, i.e., two attractive 3D zerorange potentials (ZRP) separated by a distance $R$, in a static electric (DC) field ${\bf F}$. For this model, both the Green function and the equation for its poles (resonances) are expressed in terms of Airy functions. For a weak field $F$, we obtain simple analytical expressions for the decay rate and polarizability for an arbitrary orientation of ${\bf F}$ with respect to the molecular axis. We also present large scale calculations of the Starkshift and decay rate as functions of $R$ and $F$. Our analyses show that decay rates are largest if the molecular axis is orthogonal to ${\bf F}$. The poles of the Green function as functions of $F$ are found numerically to include not only those for the quasistationary states but also an infinite number of broad resonances which merge to a continuum when $F$ tends to zero (as found previously for 1D [1] and 2D [2] two ZRP models). We also analyze the complex quasienergies of molecular ions in a lowfrequency AC field using an adiabatic approximation [3]. [1] H.J. Korsch and S. Mossmann, J. Phys. A {\bf 36}, 2139 (2003); [2] G. Alvarez and B. Sundaram, Phys. Rev A 68, 013407 (2003); [3] B.Borca et al., J. Phys. B {\bf 34}, L579 (2001). [Preview Abstract] 

W1.00070: Multiphoton resonant effects in strongfield ionization: origin of the dip in experimental longitudinal momentum distributions Igor Litvinyuk, Ali Alnaser, ChakraMan Maharjan, Pengquian Wang, Lew Cocke We studied ionization of neon and argon by intense linearly polarized femtosecond laser pulses of different wavelengths (400 nm, 800 nm and 1800 nm) and peak intensities, by measuring momentum distributions of singly charged positive ions in the direction parallel to laser polarization. For Ne the momentum distributions exhibited a characteristic dip at zero momentum at 800 nm, a complex multipeak structure at 400 nm and no structure at 1800 nm. Similarly, for Ar the momentum distributions evolved from complex multipeak structure (400 nm) to a smooth distribution characteristic of pure tunneling ionization (800 nm high intensities and 1800 nm). In the intermediate regime (800 nm, medium to low intensities), for both molecules we observed recoil ion momentum distributions modulated by quasiperiodic structures usually seen in the photoelectron energy spectra in multiphoton regime (ATI spectra). Ne did show a characteristic ``dip'' at low momentum, while longitudinal momentum distribution for Ar exhibited a spike at zero momentum instead. Based on our results, we conclude that the structures, observed in Ne and Ar momentum distributions, reflect the specifics of atomic structure of the two targets and should not be attributed to effects of electron recollision, as was suggested earlier. Instead, as our results indicate, they are due to effects of multiphoton resonant enhancement of strongfield ionization. [Preview Abstract] 

W1.00071: Ionization and Dissociation of O$_{2}^{+}$ and N$_{2}^{+}$ in Intense Short Pulse Laser Fields A. M. Sayler, R. CabreraTrujillo, P. Q. Wang, B. Gaire, Nora G. Johnson, M. Leonard, E. Parke, K. D. Carnes, B. D. Esry, I. BenItzhak The momentum distributions for ionization and dissociation of O$_{2}^{+}$ and N$_{2}^{+}$ exposed to intense short laser pulses have been studied experimentally using a 3D coincidence momentum imaging method. Both 790nm laser pulses of 8 to 120fs at intensities up to 10$^{15}$ W/cm$^{2}$ and 395nm pulses of 45fs at intensities up to 10$^{13}$ W/cm$^{2}$ have been used. The momentum distributions yield a rich structure in kinetic energy release and angular distribution that is used to deduce the dissociation pathways. The angular distributions for these two molecules, which are theoretically predicted to be significantly different [1], will be presented. [1] X. M. Tong, Z. X. Zhao, A. S. Alnaser, S. Voss, C. L. Cocke and C. D. Lin, J. Phys. B \textbf{38}, 333 (2005) [Preview Abstract] 

W1.00072: Effect of electron correlation on high harmonic generation of helium atoms in intense laser fields Xiaoxu Guan, XiaoMin Tong, ShihI Chu We present a timedependent generalized pseudospectral (TDGPS) approach in {\em hyperspherical coordinates} for fully {\em ab initio} nonperturbative and highprecision treatment of multiphoton electroncorrelated dynamics of atomic systems in intense laser fields [1]. The procedure is applied to the investigation of highorderharmonic generation (HHG) of helium atoms in ultrashort laser pulses at a KrF wavelength of 248.6 nm. The 6D coupled hypersphericaladiabaticchannel equations are discretized and solved efficiently and accurately by means of the TDGPS method. The effects of electron correlation and doubly excited states on HHG are explored in detail. A HHG peak with Fano line profile is identified which can be attributed to a broad resonance of doubly excited states. Comparison of the HHG spectra of the {\em ab initio} twoelectron and the single activeelectron model calculations is also presented. \vspace{1mm} \noindent [1] X. Guan, X.M. Tong, and S. I. Chu, Phys. Rev. A (in press). [Preview Abstract] 

W1.00073: Wavelengthdependence of momentumspace images of lowenergy electrons generated by short, intense laser pulses at high intensities Chakra Maharjan, Ali Alnaser, Predrag Ranitovic, Igor Litvinyuk, Charles Cocke We have measured highly resolved momentumspace images of low energy electrons generated by the interaction of short intense laser pulses with argon atoms at high intensities (tunneling regime). We have done this over a wavelength range from 400 to 800 nm. The spectra show considerable structure in both the energy and angular distributions of the electrons. Some, but not all, energy features can be identified as multiphoton resonances. The angular structure shows a regularity which transcends the resonant structure and may be due instead to diffraction. We have also measured electron momentumspace images for aligned N$_{2}$ and O$_{2}$ molecules at 800nm. Rotational wave packets were used to align the targets. We will preliminary results on the effects of alignment on the energy and angular structure. [Preview Abstract] 

W1.00074: SHORT LASER PULSE PROCESSES 

W1.00075: Creation and control of single attosecond XUV pulse by fewcycle intense laser pulse Juan J. Carrera, X.M. Tong, ShihI Chu We present a theoretical investigation of the mechanisms responsible for the production of single attosecond pulse by using fewcycle intense laser pulses. The attosecond XUV spectral is calculated by accurately integrating the time dependent Schr\"odinger equation. The detailed mechanism for the production of the XUV pulse are also corroborated by analyzing the classical trajectories of the electron. Our study shows that the first return of the rescattering electron is responsible for the high energy attosecond pulse. Furthermore, we can optimize the production of attosecond XUV pulses by modifying the trajectory of the rescattering electron by tuning the laser field envelope. [Preview Abstract] 

W1.00076: AMO Science with fsec xray pulses at the LCLS John Bozek, Louis DiMauro, Nora Berrah The Linac Coherent Light Source (LCLS), a linacdrive xray free electron laser (XFEL), is currently under construction at the Stanford Linear Accelerator Center (SLAC) with funding from the Office of Basic Energy Sciences, U.S. Department of Energy. When completed in 2008, the LCLS will provide $10^{12}  10^{13}$ xray photons at energies from 800$$8000~eV in 230~fsec pulses at 120~Hz with unprecedented flux and brightness. This regime of power and energy is completely unexplored in atomic, molecular and optical sciences (AMOS) and is expected to provide many new discoveries in lightmatter explorations. An AMOS facility at the LCLS is being designed to capitalize on the unique high flux, high field and high temporal resolution of the xray pulses generated by the light source. A brief overview of the LCLS facility will be presented along with a description of the AMO research capabilities envisioned. An AMOS working group comprised of many researchers at several institutions has contributed to the design parameters for the instrumentation under design. [Preview Abstract] 

W1.00077: Ab Initio Electronic Dynamics of H$_{2}$ in Strong Attosecond Laser Field P. S. Krstic, R. J. Harrison Using MultiConfiguration TimeDependent Hartree Fock with adaptive multiresolution methods and selfadaptive time propagation techniques with controlled accuracy we analyze ionization yields, electron spectra and highharmonic radiation of a hydrogen molecule in an attosecond strong laser pulse. We follow single and twoelectron dynamics of the process of ionization during a single field cycle, including rescattering imaging of a molecular orbital and the scattering production of harmonics. [Preview Abstract] 

W1.00078: An analytical description of carrierenvelope phase effects V. Roudnev, B.D. Esry We consider a quantum system interacting with a short intense linearly polarized laser pulse. Using the twodimensional time representation and the Floquet representation, we establish a straightforward connection between the laser carrierenvelope phase (CEP) and the wave function. This connection is simply a unitary transformation in the space of Floquet components. This approach allows us to interpret any CEP effect as an interference between the Floquet components and to put limits on using the CEP in coherent control. In particular, we discuss the dependence of the CEP effect on the pulse duration. We illustrate the theory for a twolevel system as well as for atomic and molecular systems. [Preview Abstract] 

W1.00079: Dissociation and ionization of HD$^{+}$ in intense fewcycle laser pulses P. Q. Wang, A. M. Sayler, V. Roudnev, B. Gaire, Nora G. Johnson, M. Leonard, E. Parke, K.D. Carnes, B. D. Esry, I. BenItzhak All the dissociation and ionization channels of an HD$^{+}$ molecular ion beam exposed to intense laser fields, namely H$^{+}$+D, D$^{+}$+H and H$^{+}$+D$^{+}$, have been studied simultaneously using a 3D coincidence momentum imaging method. These breakup channels are experimentally separated from each other. The laser pulse durations are from about 8 fs up to those comparable to the dissociation time scale of the molecule, with a wavelength of 790 nm and an intensity range of 10$^{13}$10$^{15}$ W/cm$^{2}$. The focus of this study is on the phenomena in fewcycle laser pulses. The 3D momentum of each fragment is retrieved from its position and time signals, which provides angular and kinetic energy release spectra for each breakup channel. The dissociation of HD$^{+}$ is found to be governed by bondsoftening and above threshold dissociation, depending on the laser intensity. The ionization of HD$^{+}$ is strongly aligned along the laser polarization and has a broad kinetic energy distribution which shifts to higher values at higher intensity. [Preview Abstract] 

W1.00080: Signatures of multiphoton and tunneling ionization in the electronmomentum distributions of atoms by intense fewcycle laser pulses Marlene Wickenhauser, Xiao Min Tong, Chii Dong Lin We present angleresolved electron momentum distributions for abovethreshold ionization (ATI) of argon in an intense, linearly polarized laser pulse. Our results were obtained by solving the timedependent Schrodinger equation and by using a model based on the strong field approximation (SFA). Many features of the spectra such as ATI peaks, their substructure in the energy domain and their dominant angular momentum can be understood within the familiar SFA model. [Preview Abstract] 

W1.00081: Interaction of cold atoms with short laser pulses. Karen Chamberlin, Derek Lilla, Kyle Taylor, Kevin Zick, Greg Taft, Hai Nguyen We present a powerful diagnostic system to observe the interaction of ultrafast laser pulses with trapped $^{87}$Rb atoms. The ionization of cold atoms and the formation of cold molecules in an intense laser field in the $\mu $K temperature range open new branches of research in chemistry, metrology, and quantum physics. However, the interaction of cold atoms with short laser pulses and the subsequent ionization or molecule formation are processes which are not well understood and can be easily misinterpreted. In our proposed experimental setup, an existing ultrafast laser system at the University of WisconsinStevens Point will be used in conjunction with Magneto Optical Trap Recoil Ion Momentum Spectroscopy (MOTRIMS) to directly measure the products formed by the interaction of ultrafast laser pulses with the cold trapped $^{87}$Rb atoms. [Preview Abstract] 

W1.00082: Normal mode selectivity in ultrafast Raman excitations in $\rm \bf C_{60}$ Guoping Zhang, Thomas F. George Ultrafast Raman spectra are a powerful tool to probe vibrational excitations, but inherently they are not normalmode specific. For a system as complicated as $\rm C_{60}$, there is no general rule to target a specific mode. A detailed study presented here aims to investigate normal mode selectivity in $\rm C_{60}$ by an ultrafast laser. To accurately measure mode excitation, we formally introduce the kinetic energybased normal mode analysis which overcomes the difficulty with the strong lattice anharmonicity and relaxation. We first investigate the resonant excitation and find that mode selectivity is normally difficult to achieve. However, for offresonant excitations, it is possible to selectively excite a few modes in $\rm C_{60}$ by properly choosing an optimal laser pulse duration, which agrees with previous experimental and theoretical findings. Going beyond the phenomenological explanation, our study shines new light on the origin of the optimal duration: The phase matching between laser field and mode vibration determines which mode is strongly excited or suppressed. This finding is very robust and may be a useful guide for future experimental and theoretical studies in more complicated systems. [Preview Abstract] 

W1.00083: Pumpprobe timedependent interferometry performed using an infrared pump and soft $x$ray probe in a COLTRIMS geometry P. Ranitovic, B. Gramkow, A. Hupach, A. Alnaser, C. Maharjan, I. Bochareva, I. Litvinyuk, L. Cocke, D. Ray, Z. Chang We have developed an apparatus for performing laserpump/$x$rayprobe experiments in a COLTRIMS (Cold Target Recoil Ion Momentum Spectroscopy) geometry. A soft $x$ray beam is produced by focusing an intense (2$^{.}$10$^{14}$ W/cm$^{2 }$ 2$^{.}$10$^{15}$ W/cm$^{2})$ and fast (6 fs  50 fs) laser beam into a thick (5 Torr  80 Torr) gaseous medium using three different techniques: an effusive jet, a gas cell and a hollow fiber. This beam is crossed with a roomtemperature effusive (10$^{3}$ Torr) gaseous target of Ar or Ne. The $x$ray beam is analyzed in terms of its flux, harmonic energies and angular divergence by measuring full three dimensional photoelectron momentum images in coincidence with the recoilions. This apparatus will be used to perform timedependent interferometry of dissociating H$_{2}^{+}$ (D$_{2}^{+})$ ions. Neutral H$_{2}$ (D$_{2})$ will be ionized and excited using an infrared pump pulse and probed after a time delay up to 240 fs with the soft xray pulses. The $x$rays will be focused onto the target, and delayed relative to the pump pulse, using a twocomponent coaxial coated mirror to select a photon energy band in the 3648 eV range. Preliminary results will be presented. *This work was supported by Chemical Sciences, Geosciences and Biosciences Division, Office of Basic Energy Sciences, Office of Science, U. S. Department of Energy. [Preview Abstract] 

W1.00084: Probing Fast Dynamics in N$_{2}$ and H$_{2}$ molecules in strong laser field with ultrashort pulses Irina Bocharova, Chakra Maharjan, Ali Alnaser, Dipanwita Ray, Lewis Cocke, Igor Litvinyuk We used pumpprobe technique with fewcycle pulses and COLTRIMS detection to study dynamics of ionization and dissociation of molecules following ionization/excitation by a strong field of ultrashort laser pulse. We detected in coincidence pairs of H$^{+}$ ions and single and multiple charged ions of nitrogen N$^{q+}$ produced by pump and probe pulses in ionization and dissociation processes. Setting the delay between the two pulses we measured the kinetic energy release dependence on the delay time, which vibrational and dissociative dynamics. We were able to follow the contribution of each separate channel to the total ions yield at each delay. [Preview Abstract] 

W1.00085: PHOTON INTERACTIONS WITH ATOMS, IONS, AND MOLECULES 

W1.00086: The role of plasma oscillations of C60 collectivized electrons in photoionization of 5s subshell of Xe atom in Xe@C60 Miron Amusia, Arkadiy Baltenkov It is demonstrated that the plasma oscillations of collectivized electrons of the fullerene C60, affects dramatically the photoionization cross section of the 5ssubshell of the endohedral Xe. The calculations were performed within the framework of a simple ``orange skin'' model that makes it possible, in spite of its simplicity, to describe the modification of photoionization cross section of encapsulated atom due to the photoelectron's waves reflection by the C60 shell. It is shown that the virtual excitations of collectivized electrons in fullerenes shell become decisively important when the photon frequency is close to the frequencies of plasma oscillations of the C60. These calculations illustrate the role of the intershell interactions in the fullerenelike molecules, qualitatively similar but even stronger than in the isolated atoms. [Preview Abstract] 

W1.00087: Twoelectron photoionization of endohedral atoms Miron Amusia, Evgeny Liverts, Victor Mandelzweig Using $He@C_{60}$ as an example, we demonstrate that static potential of the fullerene core essentially alters the differential in oneelectron energy cross section of the twoelectron ionization $d\sigma ^{++}(\omega,\varepsilon )/d\varepsilon $. We found that at high photon energy prominent oscillations appear in it due to reflection of the second, slow electron wave on the $ C_{60}$ shell, which dies out at relatively high $\varepsilon $ values, of about 2$\div $3 twoelectron ionization potentials. The results were presented for ratios $R_{C_{60}}(\omega ,\varepsilon )\equiv d\sigma ^{++}(\omega ,\varepsilon )/d\sigma ^{a++}(\omega,\varepsilon)$, where $d\sigma^{a++}(\omega,\varepsilon) /d\varepsilon$ is the twoelectron differential photoionization crosssection. We have calculated also the ratio $R_{i,ful}=\sigma_i^{++}(\omega)/\sigma_i^{a++}(\omega)$, that accounts reflection of both photoelectrons by the $C_{60}$ shell. We have calculated also the value of twoelectron photoionization cross section $\sigma ^{++}(\omega )$ and found that this value is close to that of an isolated $He$ atom. [Preview Abstract] 

W1.00088: Laser Threshold Photodetchment Spectroscopy of the P Ion D. Pegg, P. Andersson, C. Alfredsson, C. Diehl, G. Collins, D. Hanstorp, P. Schef, R. Thomas The electron affinity of the P atom and the fine structure splittings of the P$^$($^3$P$_J$) state have been measured in high resolution by use of the Laser Threshold Photodetachment method. In the collinear beams experiment, tunable infrared radiation from an OPO/OPA system was used to detach an electron from the P ion. The relative cross section for the process was monitored by detecting the residual ground state P atom. Three thresholds were observed, corresponding to the opening of the channels: $\gamma$ + P$^$(3s$^2$3p$^4$ $^3$P$_J$) $\rightarrow$ P(3s$^2$3p$^3$ $^4$S$_{3/2}$) + e$^$ with J=2,1,0. The Wigner law was fitted to the threshold data and used to determine the threshold energies. The Doppler shift associated with the moving ions was eliminated by determining their velocity using the measured the red and blueshifted threshold energies associated with coand counterpropagating laser and ion beams [1]. A calibrated wavemeter was used to establish the wavelength scale of the OPO/OPA system. The newly measured values of the electron affinity of the P atom and the fine structure intervals of the P ion represent a significant improvement in precision over the current recommended values [2]. [1]. P.Juncar, et al., Phys. Rev. Lett., 54, 11(1985). [2] T.Andersen, H.K.Haugen and H.Hotop, J. Phys. and Chem. Ref. Data, 28, 1511 (1999). [Preview Abstract] 

W1.00089: Nearthreshold Innershell Photodetachment of Atomic Negative Ions: Postcollision Interactions and the Validity of the Wigner Law R.C. Bilodeau, N. Berrah, I. Dumitriu, J.D. Bozek, G.D. Ackerman, C.W. Walter, N.D. Gibson, A. Aguilar The first studies of innershell photodetachment threshold laws will be presented. Experiments were conducted on the IonPhoton Beamline on Beamline 10.0.1 at the Advanced Light Source. Innershell detachment of negative ions results in a coreexcited neutral atom that quickly emits one or more further electrons (Auger decay) to produce positive ion products that are detected as a function of photon energy. Photodetachment of a 1s electron in He$^{}$ [1] is found to be consistent with the Wigner pwave threshold law despite strong postcollision interaction effects [2]. Photodetachment cross sections near the 2s and 2p thresholds in S$^{}$ are found to closely follow the Wigner p and swave laws respectively over a surprisingly large range, even when a total of 3 or 4 electrons are emitted [1]. Detailed analysis of these threshold law behaviors and high chargestate formation [3] will be presented. [1] R.C. Bilodeau \textit{et al.}, Phys. Rev. Lett. \textbf{95, }083001 (2005). [2] R.C. Bilodeau \textit{et al.}, Phys. Rev. A (in press). [3] R.C. Bilodeau \textit{et al.}, Phys. Rev. A \textbf{72}, 050701(R), (2005). [Preview Abstract] 

W1.00090: Photodetachment Spectroscopy of Ce$^{}$ C.W. Walter, N.D. Gibson, K.A. Starr, C.M. Janczak, D.A. Richardson, P. Andersson Tunable infrared and visible laser photodetachment spectroscopy has been performed on Ce$^{}$ using a crossed laserion beam apparatus. The relative photodetachment cross section for neutral production was measured over the photon energy range 0.5 eV  2.6 eV. The spectrum shows several continuum threshold features and reveals five narrow peaks associated with negative ion resonances. The present measurements will be compared to recent theoretical [1] and experimental [2] results which are in significant disagreement on fundamental physical quantities such as the electron affinity of Ce and the ground state configuration of Ce$^{}$. [1] S.M. O'Malley and D.R. Beck, Phys. Rev. A \textbf{61}, 034501 (2000); X. Cao and M. Dolg, Phys. Rev. A \textbf{69}, 042508 (2004). [2] V.T. Davis and J.S. Thompson, Phys. Rev. Lett. \textbf{88}, 073003 (2002). [Preview Abstract] 

W1.00091: Stabilization of Autoionizing States in Crossed Magnetic and Electric Fields Katarzyna Krajewska, Jerzy Z. Kami\'{n}ski We demonstrate by numerical analysis of a zerorange potential model describing a negative ion in crossed magnetic and electric fields the existence of autoionizing states. We observe that with the increasing electricfield strength the lifetime of those states increases, reaches its maximum value, and then starts decreasing rapidly. Such a stabilization has been observed before for the socalled electricfieldinduced resonances [1] but, to our knowledge, has never been recognized for autoionizing states. [1] K. Krajewska and J. Z. Kami\'{n}ski, {\it Phys. Lett.} A {\bf 301}, 369 (2002). [Preview Abstract] 

W1.00092: DIQUIS observation of n=2$\to$7 He $2pnp~^1D$ autoionizing resonances. N.L.S. Martin, B.A. deHarak, S.H. Southworth, E.P. Kanter, B. Kraessig, L. Young, R. Wehlitz We have applied the technique of DIpoleQUadrupole Interference Spectroscopy (DIQUIS) to make the first observation of an optically forbidden Rydberg series using photoelectron spectroscopy. The He $2pnp~^1D$ autoionizing levels appear as a series of resonances in the nondipole $\gamma$ parameter.\footnote{B. Kr\"assig, E.P. Kanter, S.H. Southworth, R. Guillemin, O. Hemmers, D.W. Lindle, R. Wehlitz, and N.L.S. Martin, Phys. Rev. Lett. {\bf 88}, 203002 (2002).} The experiments were carried out at the Synchrotron Radiation Center, University of WisconsinMadison using an electron spectrometer system, designed and built at Argonne National Laboratory, to efficiently measure nondipole asymmetries in photoelectron angular distributions. We will present measurements of $\gamma$ for photon energies that cover the $n=2\to7$ resonance region. Fits to the data yield values of level positions, widths, and Fano $q$ parameters. [Preview Abstract] 

W1.00093: First Observation of a Quadrupole Cooper Minimum in the Photoionization of Xe 5$p$ P.C. Deshmukh, O. Hemmers, R. Guillemin, A. Wolska, D.W. Lindle, D. Rolles, S.W. Yu, S.T. Manson The nondipole photoelectron angular distribution parameter $\xi $ (= 3$\delta +\gamma )$ for xenon 5$p_{1/2}$ and 5$p_{3/2 }$has been studied experimentally in the 80  200 eV range. In addition, calculations have been performed using the relativisticrandomphase approximation (RRPA) methodology with all relativistic single excitation/ionization channels down to 4$s$ coupled in both the dipole and quadrupole manifolds. The results show significant disagreement between theory and experiment above about 130 eV photon energy, in contradistinction to the Xe 5$s$ case where rather good agreement is found. Since it is known that the dipole amplitudes are wellrepresented by RRPA, the difficulty must be in the quadrupole channels. It was expected that the quadrupole channels should be accurate as well since the fwave is resonant in Xe and the main quadrupole transitions, the 5\textit{p$\to $}k$f$, are included in the calculation. However, we have found that these transitions each have a quadrupole Cooper minimum in the energy region of interest, so that quadrupole satellites, which are not included in the RRPA calculation, become important. This might be the first experimental indication of a quadrupole Cooper minimum. [Preview Abstract] 

W1.00094: Deviation of $\beta$ from 2.0 for the Kr and Xe $4s$ and $5s$ Photoelectrons at the $nd \rightarrow mp$ (n=3 for Kr, n=4 for Xe) Excitations S. B. Whitfield, R. Wehlitz, P. C. Deshmukh, S. T. Manson In the absence of relativistic effects, the angular distributions, $\beta$, of ssubshell electrons in closedshell atoms will be 2.0 independent of the energy of the ionizing photons. When relativistic effects are important, then deviations from this behavior can be expected and are generally more likely in the vicinity of Cooper minima, at high photon energies, or in the region of resonances [1]. We examine the latter case of the Kr $4s$ $\beta$ values in the region of the $3d \rightarrow mp \ (m \ge 5)$ excitations and the Xe $5s$ $\beta$ values in the region of the $4d \rightarrow mp \ (m \ge 6)$ excitations. We observe small but unmistakable variations of $\beta$ from 2.0 at these resonances. To understand these results in more detail we have carried out relativistic random phase calculations (RRPA). Preliminary results clearly indicate deviations of $\beta$ from 2.0 for these photolines, although the degree of variation is predicted to be larger than what is observed. We will present improved RRPA calculations as well relativistic multichannel quantum defect (RMQDT) calculations. [1] S. T. Manson and A. F. Starace, Rev. Mod. Phys. {\bf 54}, 389 (1982). [Preview Abstract] 

W1.00095: Photoionization of the 4$f$ and 6$s$ Subshells of Atomic Thulium in the Region of the 5$p$ Excitations S. B. Whitfield, K. Caspary, R. Wehlitz, M. Martins The relative partial cross sections, $\sigma$, and the angular distribution parameters, $\beta$, of the photoelectrons originating from the $4f$ and $6s$ subshells of atomic thulium have been measured in the region of the $5p$ excitations (23~eV  38~eV). In qualitative agreement with the early absorption work of Tracy [1], our $\sigma$ curves show two regions of strong resonance enhancement, one around a photon energy of 27~eV corresponding to $5p_{3/2}$ excitations and the other near 32~eV corresponding to $5p_{1/2}$ excitations. The $\beta$ curves show considerable variation between the allowed extremes of 1.0 and 2.0 for many of the $4f$ photolines. In addition, the $6s$ photoline shows very marked deviations from $\beta = 2.0$ which is indicative of an openshell atom. We also compare our calculated $4f$ partial cross sections, using a modified version of the Cowan code [2], with experiment. While there is good qualitative agreement between theory and experiment, quantitative details are not reproduced: i) the $5p_{3/2}$ excitations are too narrow and ii) have an intensity larger than what is observed experimentally. [1] D. H. Tracy, Proc. R. Soc. Lond. A {\bf 357}, 485 (1977), [2] M. Martins, J. Phys. B, {\bf 34}, 1321 (2001). [Preview Abstract] 

W1.00096: Resonance Structures in Photoionization of $S^+$ Swaraj Tayal Resonance structures in the photoionization of $S^+$ for the removal of a 3p or 3s electron from the ground 3s$^2$3p$^3$~$^4$S$^o$ and excited metastable $^2D^o$ and $^2P^o$ states have been studied in the Bspline Rmatrix approach. The nonorthogonal orbitals are used for an accurate description of the $S^+$ initial bound states, the final $S^{2+}$ ion plus photoelectron states and $S^{2+}$ ionic thresholds. Calculations have been carried out in 17 and 27state closecoupling approximations. The relativistic effects have been considered in the Breit Pauli Hamiltonian. Photoionization cross sections are dominated by $3s^23p^2(^1D)ns~^2D$, $3s^23p^2(^1D)nd~^2F$, $^2D$, $^2P$ and $3s3p^3(^5$S$^o$,~$^3$S$^o$,~$^3$D$^o$,~$^3$P$^o$)np~$^4$P Rydberg series of resonances. Our results will be compared with merged ionphoton beam experiment. [Preview Abstract] 

W1.00097: Photoionization of \textit{Cl} like \textit{K}$^{2+}$ and \textit{Ca}$^{3+}$ G.A. Alna'washi, M. Lu, M. Habibi, D. Esteves, J. Wang, R.A. Phaneuf, A.L.D. Kilcoyne, A. Schlachter, C. Cisneros, B. McLaughlin Absolute photoionization crosssection measurements have been performed for $K^{2+}$ and\textit{ Ca}$^{3+}$ in the energy range from the ionization thresholds of their metastable state ($^{2}P^{o}_{1/2})$ and ground state ($^{2}P^{o}_{3/2})$ to the series limit of the dominant Rydberg series of resonances. The measurements were performed using the IonPhoton Beam endstation on Beam line 10.0.1 of the Advanced Light Source (ALS) by merging an ion beam with a beam of synchrotron radiation from an undulator magnet. The data are compared to previous measurements for \textit{Cl}like \textit{Ar}$^{+}$ [1]. Most of the resonances have been characterized by multiple Rydberg series of autoionizing states and assigned spectroscopically using quantum defect form of Rydberg formula. The measurements are compared with Rmatrix calculations and with relativistic HartreeFock calculations of the energies and the oscillator strengths of the autoionizing transitions. [1]: A. M. Covington et al, Proc. XX11 ICPEAC, 48 (2001). [Preview Abstract] 

W1.00098: Innershell Photodetachment of Na$^{ }$ H. L. Zhou, S. T. Manson, A. Hibbert, T. W. Gorczyca Calculations of the photodetachment of a 2p core electron in the Na$^{}$ ion over the photon energy range 3041 eV have been performed using Rmatrix theory with a perturbative method in the asymptotic region. Our results show a very strong Feshbach resonance in the Na 1s$^{2}$2s$^{2}$2p$^{5}$2s$^{2 }(^{2}$P) channel at about 34 eV, just below the 1s$^{2}$2s$^{2}$2p$^{5}$3s3p$^{ }(^{2}$D) threshold, the 1s$^{2}$2s$^{2}$2p$^{5}$3s3p$^{2 }(^{1}$P) resonance. Since 3s and 3p orbitals are about the same ``size'', they have a significant attractive exchange interaction; this attraction pulls the resonance below the 1s$^{2}$2s$^{2}$2p$^{5}$3s3p$^{ }(^{2}$D) threshold, making it a Feshbach resonance. The Auger decay 1s$^{2}$2s$^{2}$2p$^{5}$3s$^{2 }\to $1s$^{2}$2s$^{2}$2p$^{6 }$ (Na$^{+ })+e$ leads to the production of Na$^{+}$. Therefore, we expect experiment to find this resonance around 34 eV. But recent experiment explored in this region and found nothing [1]. We are puzzled by this discrepancy. Another resonance in our calculation is located at 36.318 eV, just below the 1s$^{2}$2s$^{2}$2p$^{5}$3s4s ($^{ 2}$P$^{o})$ threshold. This resonance is confirmed by experiment [1] which is found at 36.213 eV and assigned as a 1s$^{2}$2s$^{2}$2p$^{5}$ 3s 4s \textit{nl} resonance. The situation remains under theoretical scrutiny Work was supported by DOE, NASA and NSF. [1] A. M. Covinton \textit{et al}., J. Phys. B \textbf{34}, L735 (2001) and D. J. Pegg, private communication (2005). [Preview Abstract] 

W1.00099: Photoionization and Electronimpact Ionization of Kr$^{3+}$ M. Lu, G. Alna'washi, M. Habibi, R.A. Phaneuf, A.L.D. Kilcoyne, A.S. Schlachter, C. Cisneros, G. Hinojosa Using synchrotron radiation, photoionization cross sections for Kr$^{3+}$ were measured in the energy range 39  143 eV for singleionization and 120  137 eV for doubleionization. For comparison, electronimpact single ionization was measured in the energy range 43  179 eV. The Flexible Atomic Code (FAC) and Cowan atomic structure code were used to calculate energy levels, excitation and ionization energies and oscillator strengths for autoionizing transitions from the ground and metastable states. Ionization thresholds of metastable states ($^{2}$P$^{o}_{3/2}$, $^{2}$D$^{o}_{5/2})$ and ground state ($^{4}$S$^{o}_{3/2})$ were measured to be 46.62, 48.59 and 50.70 eV, 12 eV lower than NISTtabulated values. Shifting the theoretical 3d4p spectra by +1.56 eV for the FAC code and +0.81 eV for the Cowan code brings them into good agreement with experiment. Measured oscillator strengths agree with the calculations within experimental uncertainty. Resonant excitationdoubleautoionization features are evident in the electronimpact ionization spectrum. [Preview Abstract] 

W1.00100: Randomphase approximation with exchange for innershell electron transitions II: Effects of intershell correlations Zhifan Chen, Alfred Z. Msezane A randomphase approximation with exchange (RPAE) method, which allows the inclusion of both the intrashell correlations and the intershell correlations in photoionization calculations, has been developed for openshell atoms (ions), such as I, Xe$^+$, and I$^+$. The equations for all types of matrix elements have been derived and implimented in a computer code. The program has been used to study the effects of intershell correlations on the Xe$^+$ 5$s$, 5$p$ and $4d$ photoionization processes, which are found to increase dramatically the cross sections for the Xe$^+$ $5s$ and $5p$ eletrons. [Preview Abstract] 

W1.00101: Kshell photoionization of Lilike carbon ions: experiment, theory and comparison with timereversed photorecombination A. M{\"u}ller, S. Schippers, R.A. Phaneuf, S.W.J. Scully, A. Aguilar, E.D. Emmons, M.F. Gharaibeh, J.D. Bozek, A.S. Schlachter, G. Hinojosa, C. Cisneros, B.M. McLaughlin Absolute crosssections for the Kshell photoionization of Lilike C$^{3+}$(1s$^2$\,2s\,\,$^2$S) ions were measured by employing the ionphoton mergedbeams technique at the Advanced Light Source. The energy ranges 299.8300.15 eV, 303.29303.58 eV and 335.61337.57 eV of the [1s\,(2s\,2p)$^3$P]$^2$P, [1s\,(2s\,2p)$^1$P]$^2$P and [(1s\,2s)$^3$S\,\,3p]$^2$P resonances, respectively, were covered using resolving powers of up to 6000. The width of the [1s\,(2s\,2p)$^1$P]$^2$P resonance was measured to be $27 \pm 5$~meV and compares favourably with a theoretical result of 25.5 meV obtained from the RMatrix method. The present photoionization results are compared with the outcome of the photorecombination measurements by employing the principle of detailed balance. The agreement between both experimental approaches is within the experimental uncertainties. Further details will be presented at the meeting. [Preview Abstract] 

W1.00102: Asymmetry of the Compton profile Barun K. Chatterjee, Suprakash C. Roy, Tihomir Suri\'{c}, Larry A. Lajohn, Richard H. Pratt Compton scattering of a photon by bound electrons is one of the fundamental processes of interaction of radiation with matter. It is often used to investigate structure of atomic systems, molecules and solids. In studying structure, an approximate theoretical approach is used (impulse approximation, IA) which allows interpretation of the measurements in terms of the structure of the system under investigation. Accurate measurements of the Compton profile (which is an appropriately normalized Compton scattering doubly differential cross section, differential in outgoing photon energy and angle) have revealed discrepancies between measurements and simple IA results. These discrepancies are described as an asymmetry of the Compton profile. We investigate these asymmetries numerically by using Smatrix calculations of the Compton process, and we find that they can largely be understood as a shift of the Compton profile maxima. We compare our results with other theoretical investigations of this issue. [Preview Abstract] 

W1.00103: Double Excitations of Helium in Weak Static Electric Fields T. W. Gorczyca, F. Robicheaux, C. S\aa the, M. Str\"om, J.E. Rubensson, R. Richter, M. Alagia, S. Stranges A dramatic electric field dependence has been observed in the photofluorescence yield spectrum of the doubly excited states in helium, where a rich phenomenology is encountered below the $N=2$ threshold. Fluorescence yields of certain states can be tuned to zero, while other dipoleforbidden states are significantly enhanced, for fields much weaker than 1 kV/cm. Using an Rmatrix multichannel quantum defect theory, sphericaltoparabolic frame transformation method, we are able to reproduce the main features of the observed spectrum, and we explain the qualitative behavior in terms of weak electric field mixing. [Preview Abstract] 

W1.00104: Doubly Excited Resonances in the Photoionization Spectrum of Li$^{+}$: experiment and theory S.W.J. Scully, E.D. Emmons, M.F. Gharaibeh, R.A. Phaneuf, D. Leitner, A.S. Schlachter, A. M\"{u}ller, S. Schippers, R. P\"{u}ttner, M.S. Lubell, I. \'{A}lvarez, C. Cisneros, C.P. Ballance, B.M. McLaughlin Absolute crosssection measurements for resonant double photoexcitation of Li${^+}$ ions followed by subsequent autoionization have been performed in the photon energy range from 148 eV, just below the (2s2p, $_2$(0,1)$_2^+$) resonance to 198 eV (the region of the double ionization threshold) at high resolution. The measurements have been made using the photonion mergedbeam endstation at the Advanced Light Source, Lawrence Berkeley National Laboratory. The absolute cross section measurements when compared with theoretical results from the Rmatrix plus pseudostate (RMPS) method show excellent agreement. Comparisons made between theory and experiment for the Auger resonance energies, autoionization linewidth ($\Gamma$) and the Fano line profile index $q$ for several members of the principal (2snp, $_2$(0,1)$_n^+$) and (3snp, $_3$(1,1)$_n^+$) Rydberg series found in the photoionization spectra for the $\rm ^1P^o$ symmetry show suitable accord. Further details will be presented at the meeting. [Preview Abstract] 

W1.00105: Resonant Double Photoionization of Li Studied with High Energy Resolution R. Wehlitz, P.N. Jurani\'c Employing monochromatized synchrotron radiation of the new VLSPGM beamline at the Synchrotron Radiation Center (SRC), we have measured with high energy resolution the relative photoionization crosssections for the formation of Li$^{+}$ and Li$^{2+}$ ions between 148 and 161 eV photon energy. This energy region is characterized by double and triple excitations that lead to strong enhancements in the cross sections, particularly in the Li$^{2+}$ cross section. In an earlier study performed by Huang {\it et al.} \footnote{M.T.\ Huang, R.\ Wehlitz, Y.\ Azuma, L.\ Pibida, I.A.\ Sellin, J.W.\ Cooper, M.\ Koide, H.\ Ishijima, and T.\ Nagata, Phys.\ Rev.\ A {\bf 59}, 3397 (1999)} only a moderate energy resolution was used. Our highresolution data exhibit a dramatic resonance structure in the doubletosingle ionization ratio not seen before. [Preview Abstract] 

W1.00106: Design and Commissioning of a new Ion Momentum Imaging Spectrometer Daniel Rolles, Mark Perri, Rene Bilodeau, David Kilcoyne, Glenn Ackerman, John Bozek, Nora Berrah We have built a velocity map ion imaging spectrometer designed for valence and coreshell photoionization studies of molecules, ions and clusters. The spectrometer is equipped with 4 electrostatic lenses, which focus the fragment ions on a positionsensitive Roentdek Hex80 anode. It can be employed for electronion coincidence experiments in both multi as well as twobunch mode using static or pulsed ion extraction fields. First results for the photoionization of small molecules and clusters will be presented. [Preview Abstract] 

W1.00107: Dipole and nondipole photoelectron angular distributions of molecular hydrogen S.H. Southworth, E.P. Kanter, B. Kraessig, R. Wehlitz, B. Zimmermann, V. McKoy Molecular hydrogen has long been a prototype system for experimental and theoretical studies of photoionization. Measurements of angleintegrated cross sections and the anisotropy parameter $\beta $ provide experimental tests of molecular photoionization theory and calculational approaches within the dipole approximation. Nondipole interactions distort dipole angulardistribution patterns and can be probed by measurements of forwardbackward asymmetries with respect to the photon propagation vector. Nondipole asymmetries can be calculated to first order in theoretical treatments that include cross terms between electricdipole and electricquadrupole or magneticdipole photoionization amplitudes. In this work we report measurements of the dipole anisotropy parameters $\beta $ and the nondipole asymmetries $\gamma $+3$\delta $ of H$_{2}$ over the 20150 eV photonenergy range. Comparison is made with calculations based on firstorder corrections to the dipole approximation with amplitudes calculated within the singlechannel, staticexchange approximation. [Preview Abstract] 

W1.00108: Doublephotoionization of CO few eV above threshold A. Belkacem, T. Osipov, M. Hertlein, M. Prior, H. Adaniya, B. Feinberg, Th. Weber, T. Jahnke, R. Dorner, L. Schmidt, M. Schoffler, O. Jagutzki, C.L. Cocke, A. Landers We measured double photoionization of CO molecules at 48 eV photon energy. The double ionization of CO produces mostly C$^{+}$ + O$^{+}$ fragments with nonmeasurable amounts of CO$^{2+}$. The formation of C$^{+}$ + O$^{+}$ can proceed through two possible channels: a) Direct ionization of two electron into the continuum  similar to the H2 double ionization  direct channel. b) Ionization of one electron into the continuum followed by autoionization of a second electron  Indirect channel. The electron distribution measured with a COLTRIMS shows a very clear distinction of the direct and indirect channels. The kinetic energy release spectrum shows a series of peaks corresponding to the transient vibrational states of the various electronic states of (CO$^{2+})$*. These states are similar to previous measurements at higher energies (Kshell photoionization). (CO$^{2+})$* is found to predissociate through a $^{3}\Sigma ^{}$ and $^{1}\Delta $ dissociative states leading to considerably faster dissociation times than natural lifetimes of the electronic bound states. [Preview Abstract] 

W1.00109: $N_2^+ $ fluorescence in photoionization of $N_2 $ by 16.3150 eV photons J.R. Machacek, T.J. Gay, J.E. Furst, A.L.D. Kilcoyne, J.D. Bozek, H. Gould, M.S. Lubell, K.W. McLaughlin We have studied the intensity of fluorescence from the $B^2\Sigma _u^+ X^2\Sigma _g^+ $ (${\nu }'=1,{\nu }''=4)$ transition (514.9 nm) in $N_2^+ $ as a function of incident photon energy following the photoionization of $N_2 $ by linearly polarized light with energy between 16.3 and 150 eV. This experiment was conducted at beamline 10.0.1.2 of the ALS. To our knowledge, this measurement represents the first unambiguous observation of a specific molecular transition in such collisions. A broad maximum peaked at $\sim $23 eV is observed in the production cross section for this specific vibrational state. Nonstate specific measurements were taken from 115 to 200 nm which includes multiple $N^+$ ionic fluorescence lines as previously measured from 19.7 to 37.6 eV by Erman \textit{et al.} [1]. Our current measurements extend this observation from 16.3 to 150.0 eV. [1] P. Erman \textit{et al.}, J. Phys. B \textbf{26} (1993) 4483. [Preview Abstract] 

W1.00110: Acetylene/Vinylidene Isomerization after Carbon Kshell PhotoIonization Timut Osipov, T. Weber, T. Jahnke, A. Alnaser, A. Landers, M. Hertlein, O. Jagutzki, L. Schmidt, M. Sch\"offler, M. Prior, B. Feinberg, C. L. Cocke, R. D\"orner, A. Belkacem Comprehensive study of the acetylene/vinylidene isomerization dynamics after the carbon kshell photoionization followed by the Auger decay was performed by means of the COLTRIMS (COLd Target Recoil Ion Momentum Spectroscopy) technique. The Auger electrons, produced in this reaction, were detected in coincidence with the products of the Coulomb explosion of the dication C$_{2}$H$_{2}^{2+}$. Measurement of the 3d vector momenta for all detected particles inferred the Auger electron energies and directions in the body fixed molecular frame along with the KER (Kinetic Energy Release) for different break up channels. This highly differential reaction crosssection study provided very unique information about the fragmentation pathways of the doubly charged acetylene molecule. [Preview Abstract] 

W1.00111: Modulations in the Relative DoublePhotoionization Cross Section P.N. Jurani\'c, K. Barger, D. Luki\'c, R. Wehlitz A modulation in the C$_{60}^{2+}$/C$_{60}^{+}$ photoionization crosssection ratio has been observed by using monochromatized synchrotron radiation between 19 and 280 eV \footnote{P.N.\ Juranic {\it et al.}, Phys.\ Rev.\ Lett. {\bf 96}, 023001 (2006)}. The modulations in the ratio have local maxima at certain excess energies (=photon energy minus doubleionization threshold). Each energy corresponds to an electron's de Broglie wavelength that fits between certain locations of two carbon atoms in the C$_{60}$ molecule. While these modulations are small at nearthreshold energies, they become much more pronounced at higher energies. It seems that in the doublephotoionization process, one of the electron bounces between two carbon atoms if its de Broglie wavelength matches that distance. Eventually, it will transfer some of its energy to the second electron, which is then able to escape together with the first electron. [Preview Abstract] 

W1.00112: Photodetachment of the Terbium Anion Srividya S. Duvvuri, Rick G. Kraus, Erik D. Emmons, Jeffrey S. Thompson, Vern T. Davis, Aaron M. Covington Laser Photodetachment Electron Spectroscopy (LPES) has been used to study the terbium anion. Photoelectron kinetic energy spectra were measured at photon energies ranging from 457.9514.5 nm using a crossed laserion beams apparatus. In addition, photoelectron angular distributions were measured as a function of the angle between the laser polarization vector and the linear momentum vector of the collected photoelectrons. Photoelectron kinetic energy spectra from the photodetachment of Na$^{}$ and C$^{}$ were used to calibrate the energy scale for the Tb$^{}$ photoelectron energy spectra. Preliminary results from the analysis of these data will be presented. [Preview Abstract] 

W1.00113: Improvements in the understanding of the spectrum and photodetachment of Ce$^$ Steven M. O'Malley, Donald R. Beck We have undertaken new relativistic configuration interaction calculations of the electron affinity of the $4f~5d^2~6s^2$ $^4$H$_{7/2}$ Ce$^$ ground state in an effort to resolve the differences among our earlier work\footnote{S. M. O'Malley and D. R. Beck, Phys. Rev. A {\bf 61}, 034501 (2000)} (428 meV), newer calculations\footnote{X. Cao and M. Dolg, Phys. Rev. A {\bf 69}, 042508 (2004)} (530 meV), and the much larger experimental value\footnote{V. T. Davis and J. S. Thompson, Phys. Rev. Lett. {\bf 88}, 073003 (2002)} (955 meV). Inclusion of correlation involving the $4f$ electron brings us in good agreement with the other calculation$^3$ (511 meV), but addition of corevalence effects that would further bind the system is prohibitively difficult: several eV of corevalence correlation disrupts the relative positioning of the valence correlation configurations, resulting in unacceptable (up to $\sim$30\%) losses in their energy contributions. Thus, instead of opening the core, we have made a series of photodetachment cross section calculations. These results, along with a reinterpretation of the experimental data$^4$, lead us to a new value for the Ce$^$ electron affinity of $\sim$660 meV. [Preview Abstract] 

W1.00114: ATOMIC, MOLECULAR AND CHARGED PARTICLE COLLISIONS AND SPECIAL TOPICS 

W1.00115: Efficient Rydberg Excitation of He with STIRAP SH. Lee, K. Choi, J. Kaufman, A. Vernaleken, O. Kritsun, H. Metcalf We have used Stimulated Rapid Adiabatic Passage (STIRAP)\footnote{U. Gaubatz et al., Chem. Phys. Lett., {\bf 149} 463 (1988)} for highly efficient excitation of Rydberg states, and developed an absolute measure of the efficiency. The metastable 2$^3$S$_1$ state (He*) comes from a dc discharge atomic beam source. A blue laser beam ($\lambda$ = 389 nm) excites He* to the 3$^3$P$_2$ state, and a red laser beam ($\lambda$=796 nm) then excites the 26$^3$S$_1$ state. If this intuitive order of excitations is reversed (STIRAP) the theoretical excitation efficiency $\rightarrow$ 100\%. In our experiment, He* atoms cross both blue and red beams whose positions can be shifted to affect the order that the atoms encounter them. We observed a large increase in the Rydberg population as we shift the red beam upstream of the blue one (the counterintuitive order appropriate for STIRAP). We also use 389 nm light to measure the excitation efficiency with blue detuned optical molasses directly downstream of the STIRAP area. It spreads the spatial distribution of remaining He* but Rydberg atoms are unaffected. We present the results of our first measurements. [Preview Abstract] 

W1.00116: AutlerTownes Effect in Rydberg Excitation of Metastable He Atoms SH. Lee, K. Choi, J. Kaufman, A. Vernaleken, O. Kritsun, H. Metcalf We have studied the AutlerTownes (AT) effect in the twostep excitation of He atoms from the metastable 2$^3$S$_1$ state (He*) that serves as an initially populated ground state in an atomic beam (He* is produced in a dc discharge source). A relatively strong blue laser ($\lambda$ = 389 nm) couples this He* state to the 3$^3$P$_2$ state, which in turn can be excited to the 26$^3$S$_1$ Rydberg state by a relatively weak red laser ($\lambda$ = 796 nm) that serves as a probe. Keeping the laser frequencies fixed, we exploit the large Stark shift of the Rydberg state to measure the AT splitting of the 3$^3$P$_2$ state {\it vs.} the intensity of the 389 nm light. We do this by scanning a weak dc electric field (few V/cm) and observing the AT effect through the subsequently ionized Rydberg atoms using an ion detector located just downstream of the field plates (the scan amplitude exceeds the AT splitting). We compare our experimental results with a dressed atom picture of the AT effect. [Preview Abstract] 

W1.00117: POSTDEADLINE 

W1.00118: Collapse in Mixture of Two Component Fermi Gases V.R. Shaginyan, A.Z. Msezane, M.Ya. Amusia Trapped Fermi alkali gases are spin polarized and cannot interact in the swave channel. A two component system realized by mixtures of two Fermi alkali gases, say $^6$Li and $^{40}$K, interacts in an swave channel and can be viewed as a Fermi gas with effective scattering length $a_{LK}$. Our consideration based on the thermodynamic properties gives strong evidence that the compressibility becomes negative as soon as $a_{LK}$ is negative and sufficiently large. As a result, the system collapses when $p_Fa_{LK}\sim1$, where $p_F$ is the Fermi momentum. In the regime of large particle numbers in mixtures such as in traps, the Fermi momentum can be estimated as $p_F\simeq (3\pi^2\rho)^{1/3}$ with $\rho$ the average number density of the mixture. Our prediction [M.Ya. Amusia, A.Z. Msezane, and V.R. Shaginyan, Phys. Lett. A{\bf 293}, 205 (2002)] that two component systems composed of Fermi and Bose gases, which retain the significant features of the considered two component Fermi system, collapse is in good agreement with recent facts [C. Ospelkaus {\it et al.,} Phys. Rev. Lett. {\bf 96}, 020401 (2006)]. Our results suggest that the equation of state of a low density neutron matter has peculiarities at $a_{nn}p_F\sim 1$ ($a_{nn}$ is the neutronneutron scattering length), which can lead to the equilibrium state of neutron matter. [Preview Abstract] 

W1.00119: New Parallel DivideandConquer Algorithm for Computing Full Spectrum of Polyacetylene Yihua Bai, Bob Ward, Guoping Zhang The SuSchriefferHeeger (SSH) model is a simple tightbinding model that includes nearest neighbors and is frequently used to study the fundamental properties of transpolyacetylene (transPA), as well as many other materials. In these studies, the essential and most time consuming step is the computation of the eigendecomposition of the Hamiltonian matrix. In this poster, we present a new scalable parallel algorithm that efficiently computes the full spectrum of Hamiltonian matrices to a prescribed accuracy. Given an accuracy tolerance $\tau$ and Hamiltonian matrix $A$, which is a real symmetric dense matrix, our parallel algorithm fully exploits the structure of the Hamiltonian matrix and computes eigensolutions in two steps: (a) Construct a blocktridiagonal matrix that approximates the original dense matrix; (b) Use the highly efficient blocktridiagonal divideand conquer algorithm to compute approximate eigensolutions. The computed approximate eigensolutions satisfy the following conditions: 1) $ AV\Lambda V^T \le O(\tauA) $; and 2) $ (VV^T  I) \le O(n\epsilon_{mach}) $, where $\epsilon_{mach}$ is the machine precision. Performance tests show that this algorithm is extremely efficient for the computation of electronic spectrum of transPA compared to traditional dense eigensolvers. In many tests, the savings is several orders of magnitude! [Preview Abstract] 

W1.00120: LiouvilleSpace Descriptions for IntenseField Coherent Electromagnetic Interactions Verne Jacobs Liouvillespace (reduceddensityoperator) descriptions are developed for coherent electromagnetic interactions of quantized electronic systems, taking into account environmental decoherence and relaxation phenomena. Applications of interest include manyelectron atomic systems and semiconductor nanostructures. Time domain (equationofmotion) and frequencydomain (resolventoperator) formulations are developed in a unified manner. In a preliminary semiclassical perturbative treatment of the electromagnetic interaction, compact Liouvillespace operator expressions are derived for the linear and the general (n’th order) non linear electromagneticresponse tensors. Intensefield electromagnetic interactions are treated by an alternative reduceddensityoperator approach based on the Liouvillespace FloquetFourier representation. [Preview Abstract] 

W1.00121: Recurrence Tracking Microscope: Atom optics for nanoscience Farhan Saif In order to probe nanostructures on a surface we present a microscope based on atom optics laws. A cloud of atoms bounces off an atomic mirror connected to a cantilever and exhibits quantum recurrences. The times at which the recurrences occur depends on the initial height of the bouncing atoms above the atomic mirror, and varies following the structures on the surface under investigation. The microscope has inherent advantages over existing techniques of scanning tunneling microscope and atomic force microscope. Presently available experimental technology makes it possible to develop the device in the laboratory. [Preview Abstract] 

W1.00122: Measurement of Excited State Lifetime Using TwoPulse Photon Echoes in Rubidium Vapor Eric Rotberg, Scott Beattie, Iain Chan, Brynle Barrett, Eric Paradis, A. Kumarakrishnan We have observed twopulse photon echoes in a Doppler broadened rubidium vapor. The system interacts with traveling wave optical pulses that are $\sim $20 ns in duration. The pulses are on resonance with the F=3  F'=4 transition in $^{85}$Rb and F=2  F'=3 transition in $^{87}$Rb. They are generated from a CW laser using acoustooptic modulators. The first pulse, occurring at t=0, induces a macroscopic dipole moment that dephases due to atomic motion. The second pulse, occurring at t=T, reverses the direction of the dephasing process so that the echo is formed at t=2T. The echo is detected using a heterodyne technique and its intensity decays exponentially as a function of 2T. We report a measurement of the excited state lifetime precise to $\sim $1{\%} that is in agreement with a previous measurement. Our results suggest that the excited state lifetime can be determined to a precision of $\sim $0.25 {\%} by additional data accumulation and by a more comprehensive study of systematic effects. [Preview Abstract] 

W1.00123: Experimental Studies of Decoherence using a Single State Atom Interferometer Scott Beattie, Matthew Weel, Iain Chan, S. Chudasama, A. Kumarakrishnan We have measured the decay time of a ground state grating echo produced by off resonant standing wave pulses tuned to the vicinity of the $F=3 \rightarrow F'=4 $ transition in trapped $^{85}Rb$ atoms. The time scale of the decay $(\sim 20 $ms$)$ is determined primarily by the transit time of the cold atoms through the region of interaction and is sufficiently long to investigate effects of decoherence due to light and velocity changing collisions. We find that the decay rate exhibits an exponential dependance on light intensity and scales inversely as the square of the detuning with respect to the excited state. We have also observed the effect of diffractive collisions on the decay time by varying the pressure of the background rubidium atoms. The data can be used to infer the total cross section for collisions between hot and cold rubidium atoms. These studies allow the time scale of the echo signal to be extended making it feasible to improve the precision of our measurement of $\hbar/M_{Rb}$. [Preview Abstract] 

W1.00124: Effect of a magnetic field gradient and gravitational acceleration on a time domain grating echo interferometer David Gosset, Itay Yavin, Matthew Weel, Iain Chan, Scott Beattie, A. Kumarakrishnan We have observed the effects of magnetic field gradients and gravitational acceleration on grating echoes in a time domain single state atom interferometer that uses laser cooled Rb atoms. These observations are compared to theoretical predictions based on a simplified model. The oscillatory dependence of the echo amplitude due to the magnetic field gradient is in agreement with the predicted quadratic scaling as a function of the time between excitation pulses. We also observe a linear dependence of this oscillation frequency as a function of the magnetic field gradient which is predicted by theory. In the presence of gravity, the calculations predict a quadratic dependence for the echo phase on the time between excitation pulses as well as a change in the shape of the echo envelope. We have observed both of these effects in the experiment, and we find that the change in shape is qualitatively consistent with our prediction. It is necessary to understand these effects in order to carry out high precision studies of the atomic fine structure constant and gravitational acceleration using this interferometric technique. We also present an improved measurement of gravitational acceleration using this technique that is precise to $\sim 15$ppm by exploiting the quadratic phase dependence. [Preview Abstract] 

W1.00125: Measurement of atomic g factor ratios using laser cooled atoms Iain Chan, Scott Beattie, A. Kumarakrishnan We have used pulsed laser excitation to create a spatially periodic coherence grating between adjacent magnetic sublevels of the ground state in a cloud of trapped Rb atoms. The light scattered from the grating exhibits Larmor oscillations in the presence of a magnetic field with the frequency defined by the energy level splitting between magnetic sublevels. We describe the progress in our measurements of the atomic g factor ratio using the F=3 to F’=4 transition in $^{85}$Rb and the F=2 to F’=3 in $^{87}$Rb. The current level of precision is $\sim$25 ppm achieved by acquiring data for about four hours. We describe studies of systematic effects due to fluctuating ambient magnetic fields and AC Stark shifts with the goal of achieving a precision of less than 1 ppm. [Preview Abstract] 

W1.00126: Threebody resonances using slow variable discretization coupled with complex absorbing potential Juan Blandon, Viatcheslav Kokoouline, Francoise MasnouSeeuws We are investigating threebody resonances for a model threeparticle problem using the slow variable discretization method of Tolstikhin \textit{et al.} [1] coupled with a complex absorbing potential. We compare the results with those of Fedorov \textit{et al.} [2]. We will also present preliminary calculations on Efimov resonances using our method. Efimov states are a universal set of bound trimer states which appear when there is a twobody weaklybound or virtual state [3]. Bound states of Efimov trimers have been studied in a number of theoretical treatments. Efimov resonances can be viewed as threebody Feshbach resonances that decay into a twobody bound system and a free third body (diatomic molecule + free atom, for example). Recent experimental evidence for Efimov trimers in an ultracold gas of Cs atoms obtained by Kraemer \textit{et al.} [4] has made the study of their resonances especially relevant. [1] O. I. Tolstikhin \textit{et al.}, \textit{J. Phys. B: At. Mol. Opt. Phys.} \textbf{29}, L389 (1996). [2] D. V. Fedorov \textit{et al.}, \textit{Few Body Systems} \textbf{33}, 153 (2003). [3] B. D. Esry \textit{et al.}, \textit{Phys. Rev.} \textbf{A54}, 394 (1996) and references therein. [4] T. Kraemer \textit{et al.}, \underline {arxiv.org/abs/condmat/0512394} [Preview Abstract] 

W1.00127: Detecting phonons and persistent currents in toroidal BoseEinstein condensates Franco Dalfovo, Michele Modugno, Cesare Tozzo We theoretically investigate the dynamic properties of a BoseEinstein condensate in a toroidal trap. We show that a time periodic modulation of the transverse confinement gives rise to a space periodic density pattern along the torus as a consequence of parametric amplification of pairs of Bogoliubov phonons propagating in opposite directions. This process is analogous to Faraday's instability of classical fluids in annular resonators. If the trap is switched off, the periodicity of both density and momentum distributions produces a peculiar flowerlike density distribution of the freely expanding gas. By imaging the expanded condensate one obtains i) a precise determination of the Bogoliubov spectrum and ii) a sensitive detection of quantized circulation in the torus. The parametric amplification is also sensitive to thermal and quantum fluctuations. [Preview Abstract] 

W1.00128: BEC in a time varying optical dipole trap Dwight Whitaker, Paul Lindemann We have created BECs in a trap produced from a single highpowered (P$\sim$60~W) CO$_2$ laser beam. Atoms are loaded from a vapor cell MOT into a large volume dipole trap. Forced evaporation is performed by lowering the laser beam power while decresing the trap volume. This method enables us to maintian a sufficient elastic collision rate even at low temperatures. We will discuss the effects of trap volume and depth on the initial number of atoms loaded into our dipole trap as well as the limitations of our squeezing process and its effect on evaporation trajectory and condensate number. [Preview Abstract] 

W1.00129: Deterministic Production of Photon Number States via Quantum Feedback Control J.M. Geremia It is wellknown that measurements reduce the state of a quantum system, at least approximately, to an eigenstate of the operator associated with the physical property being measured. Here, we employ a continuous measurement of cavity photon number to achieve a robust, nondestructively verifiable procedure for preparing number states of an optical cavity mode. Such Fock states are highly sought after for the enabling role they play in quantum computing, networking and precision metrology. Furthermore, we demonstrate that the particular Fock state produced in each application of the continuous photon number measurement can be controlled using techniques from realtime quantum feedback control. The result of the feedback stabilized measurement is a deterministic source of (nearly ideal) cavity Fock states. An analysis of feedback stability and the experimental viability of a quantum optical implementation currently underway at the University of New Mexico will be presented. [Preview Abstract] 

W1.00130: Imaging the Mott insulator shells using atomic clock shifts Gretchen K. Campbell, Jongchul Mun, Micah Boyd, Patrick Medley, Luis Marcassa, David E. Pritchard, Wolfgang Ketterle We have used 2photon microwave spectroscopy to probe the Superfluid Mott Insulator transition in a 3D optical lattice. Using the mean field clock shift we were able to distinguish between sites with different filling factor due to their higher interaction energy. This also allowed us to directly image the shell structure of the Mott Insulator. In addition we could measure the onsite interaction and lifetime for individual shells. Filling factors of up to n=5 have been observed. [Preview Abstract] 

W1.00131: A Fermi Mixture of $^{6}Li$ and $^{40}K$ T.G. Tiecke, A. Ludewig, S.D. Gensemer, J.T.M. Walraven We report on our progress in the construction of a new apparatus for the simultaneous cooling of the Fermionic alkali isotopes $^{6}Li$ and $^{40}K$. Our goal is to cool the mixture to degeneracy and search for novel pairing mechanisms involving Fermions of different masses. We have constructed, for the first time, a 2D MOT source of cold Li atoms directly loaded from a thermal source, thereby circumventing the need for a Zeeman slower. The 2D MOT is loaded from an effusive Li oven source and the trapping light is derived from a YAGpumped dye laser. Atoms captured from the 400C thermal beam are clearly visible trapped in two dimensions by the four intersecting MOT beams. Furthermore we have constructed and realized a 2D MOT for $^{40}K$ and a double recapture MOT mixing both species. We plan to soon start loading the mixture into an optically plugged magnetic trap for evaporative cooling. [Preview Abstract] 

W1.00132: TimeDependent Waveforms Associated with Optogalvanic Transitions Excited in CO Gas Xianming Han, Vladimir Pozdin, Prabhakar Misra, Chandran Haridas We will present our experimental studies on the optogalvanic effect (OGE) in a hollow cathode lamp filled with CO gas. Our theoretical model, based on appropriate rate equations, predicts that the observed signals should be described in terms of a sum of exponential functions. We have also developed a leastsquares fitting routine that is based on the Monte Carlo method and used it to fit the optogalvanic waveforms. We were able to fit the observed OG transitions in CO using either three or four exponential functions and the fits proved to be excellent with very small residuals. [Preview Abstract] 

W1.00133: Nonperturbative quantum and classical calculations of multiphoton vibrational excitation and dissociation of Morse molecules$^1$ K.I. Dimitriou$^{2,3}$, Th. Mercouris$^3$, V. Constantoudis$^{2,3}$, Y. Komninos$^3$, C.A. Nicolaides$^{2,3}$ The multiphoton vibrational excitation and dissociation of Morse molecules have been computed nonperturbatively using Hamilton's and Schr$\phi $dinger's timedependent equations, for a range of laser pulse parameters. The timedependent Schr$\phi $dinger equation is solved by the statespecific expansion approach [e.g.,1]. For its solution, emphasis has been given on the inclusion of the continuous spectrum, whose contribution to the multiphoton probabilities for resonance excitation to a number of excited discrete states as well as to dissociation has been examined as a function of laser intensity, frequency and pulse duration. An analysis of possible quantalclassical correspondences for this system is being carried out. We note that distinct features exist from previous classical calculations [2]. For example, the dependence on the laser frequency gives rise to an asymmetry around the redshifted frequency corresponding to the maximum probability. [1] Th. Mercouris, I. D. Petsalakis and C. A. Nicolaides, J. Phys. B\textbf{ 27}, L519 (1994). [2] V. Constantoudis and C. A. Nicolaides, Phys. Rev. E \textbf{64}, 562112 (2001). \newline $^1$This work was supported by the program 'Pythagoras' which is co  funded by the European Social Fund (75\%) and Natl. Resources (25\%). \newline $^2$Physics Department, National Technical University, Athens, Greece.\newline $^3$Theoretical and Physical Chemistry Institute, Hellenic Research Foundation, Athens, Greece. [Preview Abstract] 

W1.00134: Optimal Strategies for Fast Control of Collective States of Atoms in Cavities Bereket Berhane, Mahmut Reyhanoglu The ability to control quantum mechanical states is an essential requirement for the development of reliable quantum information processing systems. We propose strategies that use subpicosecond laser pulses for optimal and fast control of the collective state of trapped neutral atoms in a cavity. We present computer simulation for experimentally feasible parameters and discuss potential applications to quantum computing technologies. [Preview Abstract] 

W1.00135: Life Time of Charge Carriers in Double Walled Carbon Nanotubes. Ioannis Chatzakis, Arifa Habib, Mikhail Zamkov, Igor Lithvinuk, Patrick Richard We investigate the nature of lowenergy excitations in double walled carbon nanotubes, DWNT, by pumping the states using fs IR pulses. The temporal evolution of the population is examined by ionizing the resulting population with delayed fs UV pulses. The electron time of flight of the ionized electrons is recorded for a range of energies above $E_{F }$to investigate the relaxation dynamics of the charge carriers. The initial, fast relaxation is attributed to the internal thermalization of the electronic system, and is primarily driven by electronelectron (ee) scattering processes. After the system returns to a FermiDirac distribution it continues to decay with a slower rate associated with electron gas cooling electronphonon (eph) interactions. We specifically want to see if the (ee) scattering in DWNT follow a Fermiliquid behavior, as observed in our previous study of MWNT$^{1}$. 1. Zamkov, M.; Woody, N.; Shan, B.; Chang, Z.; Richard, P. \textit{Phys. Rev. Lett.} \textbf{2005}, 94, 056803. [Preview Abstract] 

W1.00136: Ground state energy of dilute gas fermion/BoseEintein Condensate mixtures Deborah Santamore, Eddy Timmermans The properties of distinguishable neutral atoms embedded in a
BoseEinstein condensate (BEC) are modified by their interactions
with the surrounding superfluid  the atoms act as polarons. In
addition, when the density of the atoms is high, the atoms have
BECmediated interactions. If these atoms are indistinguishable
fermions, the mediated interactions may be the only
interparticle interactions since the shortrange atomatom
interactions are suppressed by the Pauliexclusion principle. We
have studied the manybody energy of the mixture using
perturbation theory to uncover the effects of the polaron physics
and those of mediated interactions. At low BEC density the
mediated interactions are very weak, and at high density the
interaction range becomes so short that the Pauliexclusion
principle reduces the effect. We try to find the optimal mixtures
for studying correlation physics in cold atom fermion/BEC
mixtures. We calculate the ground state energy as a function of
the ratio of the BECsound velocity, $c$, and the Fermi velocity,
$v_F$. When $c< 

W1.00137: Quantumoptical Spacetime Wave Frames: When light coordinates itself coherently William Harter, Justin Mitchell Careful reexamination of details of quantum and classical optical wave interference leads to a more precise and elegant logic for two of the foundations of modern physics, special relativity and quantum theory. This provides a transparent unified development of both subjects together in a few simple logical steps with improved intuition and fewer ``mysteries.'' The first step is an Occam razor reduction of Einstein's axiom to a spectral form based on linear dispersion or, ``All colors go c.'' Then wave nodal planes of interfering CW beams or optical cavity modes provide their own spacetime coordinate frames with a reciprocal perspacetime lattice.[1] These clearly display LorentzPoincare symmetry and hyperbolic dispersion characteristic of quantum matter with very simple Compton recoil analyses. Accelerated coordinate frames made by cavity chirping are used to relate Compton effects to the relativistic shifts and horizons that are present in an Einstein elevator and shows them to be an elegant result of wave interference. [1] W. G. Harter, J. Mol. Spect. 210, 166 (2001) [Preview Abstract] 

W1.00138: Spinsymmetry conversion and internal rotation in high J molecular systems Justin Mitchell, William Harter Dynamics and spectra of molecules with internal rotation or rovibrational coupling is approximately modeled by rigid or semirigid rotors with attached gyroscopes. Using Rotational Energy (RE)$^{1}$ surfaces, high resolution molecular spectra for high angular momentum show two distinct but related phenomena; spinsymmetry conversion and internal rotation. For both cases the high total angular momentum allows for transitions that would otherwise be forbidden. Molecular bodyframe Jlocalization effects associated with tight energy levelclusters dominate the rovibronic spectra of high symmetry molecules, particularly spherical tops at J$>$10. $^{2}$ The effects include large and widespread spinsymmetry mixing contrary to conventional wisdom$^{3}$ about weak nuclear moments. Such effects are discussed showing how RE surface plots may predict them even at low J. Classical dynamics of axially constrained rotors are approximated by intersecting rotationalenergysurfaces (RES) that have (JS)$\cdot $B$\cdot $(JS) forms in the limit of constraints that do no work. Semiclassical eigensolutions are compared to those found by direct diagonalization. $^{1}$ W.G Hater, in \textit{Handbook of Atomic, Molecular and Optical Physics}, edited by G.W.F Drake (Springer, Germany 2006) $^{2}$\textit{ W. G. Harter, Phys. Rev. A24,192262(1981).} $^{3}$\textit{ G. Herzberg,}\underline {\textit{ Infrared and Raman Spectra}}\textit{ (VanNostrand 1945) pp. 458,463.} [Preview Abstract] 

W1.00139: Resonant electric dipoledipole interactions between cold Rydberg atoms in a magnetic field Kourosh Afrousheh, Parisa BohlouliZanjani, Jeffery Carter, Ashton Mugford, James D. D. Martin Laser cooled Rb atoms were optically excited to 46d$_{5/2}$ Rydberg states. A microwave pulse transferred a fraction of the atoms to the 47p$_{3/2}$ Rydberg state. The resonant electric dipoledipole interactions between atoms in these two states were probed using the linewidth of the twophoton microwave transitions 46d$_{5/2}$  47d$_{5/2}$. The presence of a weak magnetic field (roughly 1 G) reduced the observed line broadening, indicating that the interaction is suppressed by the field. The field removes some of the energy degeneracies responsible foe the resonant interaction, and this is the basis for a quantitative model of the resulting suppression. A technique for the calibration of magnetic field strengths using the 34s$_{1/2}$  34p$_{1/2}$ onephoton transition is also presented. [Preview Abstract] 

W1.00140: Direct femtosecond laser excitation of the 2p state of H by a resonant 8photon transition in $H_{2}^{+}$. George Gibson, Li Fang, Brad Moser We observe Lyman$\alpha$ radiation produced by the direct excitation of thermal $H_{2}$ molecules by 25fs 800nm laser pulses. The excitation proceeds in 4 steps. First the laser pulse ionizes the $H_{2}$ molecule. The $H_{2}^{+}$ molecular ion then begins to dissociate through bond softening. The expanding $H_{2}^{+}$ ion enters a region of strong multiphoton coupling with the laser field in which resonant excitation from the strongly coupled $1s\sigma_{g}$, $2p\sigma_{u}$ states to the $2s\sigma_{g}$, $3p\sigma_{u}$ states can occur. The population in the $2s\sigma_{g}$ and $3p\sigma_{u}$ states finally dissociate into H atoms in the 2s and 2p states. This scenario is supported by several independent experiments. 1) The Lyman$\alpha$ fluorescence has a linear dependence on pressure, which is consistent with direct, but not plasma, excitation. 2) A weak probe pulse delayed by 500 fs can quench the radiation, as the H(2p) state is easily ionized. This shows that the excited state is populated within 500 fs of the first pulse, again ruling out plasma excitation. 3) The radiation is seen with circularly polarized light, ruling out excitation through rescattering. 4) Ion timeofflight coincidence measurements show a new $H^{+} + H^{+}$ channel when a weak probe pulse is applied, as would be expected from the quenching experiment. All of these results are fully consistent with a new theory of highorder strongfield coupling in diatomic molecules. [Preview Abstract] 

W1.00141: Recent Experiments in Ultracold Strontium Sarah Nagel, Yenny Martinez, Pascal Mickelson, Thomas Killian We present recent work toward achieving quantum degeneracy in Strontium. In the first stage of cooling, a MOT operating on the strong ($\Gamma $= (2$\pi )$* 32 MHz), $^{1}$S$_{0}\to ^{1}$P$_{1}$ transition cools 10$^{8}$ atoms to 2 mK. Approximately 50{\%} of these atoms are transferred to a secondstage MOT operating on the weaker ($\Gamma $= (2$\pi )$* 7.5 kHz) $^{1}$S$_{0}\to ^{3}$P$_{1}$ intercombination transition, further cooling the sample to 5 $\mu $K. Here we discuss transferring this sample to an optical dipole trap and using evaporative cooling techniques to reach quantum degeneracy. [Preview Abstract] 

W1.00142: OneDimensional Cooling of an Ultracold Neutral Strontium Plasma Clayton Simien, Priya Gupta, Sampad Laha, Thomas Killian The application of laser cooling to neutral plasmas opens a wide range of experimental possibilities. This would be a new method of plasma confinement. Trapped plasma can be stored for longer times enabling detailed investigations of strong coupling, recombination at ultracold temperatures, and ionion thermalization. Recently, the ultracold plasma group at Rice has developed a high power laser source capable of laser cooling an ultracold neutral strontium plasma. Preliminary results on onedimensional laser cooling of the plasma will be presented. [Preview Abstract] 

W1.00143: Lifetime and Branching Fraction Measurements for P II~ Stephanie Torok, Mike Brown, Richard Irving, Steven Federman, Lorenzo Curtis Lifetime and branching fraction measurements using foil excitation of a fast ion beam are reported for transitions within the 3s$^2$ 3p$^2$  3s$^2$ 3p4s multiplet in P II. The studies were undertaken to test theoretical and semiempirical calculations which suggest that branching fractions within this multiplet can be accurately specified from intermediate coupling amplitudes deduced from measured energy level data. The results and their possible use a muchneeded intensity calibration standard in the vacuum ultraviolet wavelength region will be discussed. [Preview Abstract] 

W1.00144: Electron interferometry with nanofabricated gratings Herman Batelaan, Glen Gronniger, Brett Barwick, Stephanie Gilbert We have realized a three grating electron interferometer. We used free standing, metalcoated gratings with a 100 nm periodicity. Fringes are observed at 10, 8, 6, and 4 keV. Our best observed contrast is about 20 percent. This contrast exceeds our calculated maximum contrast for a Moire deflectometer by a factor of 4 and shows the quantum mechanical nature of this device. Our path integral calculation predicts a maximum contrast of about 40 percent for our experimental configuration. Our contrast does not exceed this value and is possibly limited by interferometer alignment. Our results also confirm our earlier prediction that neither image charge interaction, nor dephasing or decoherence effects prevent the construction of this electron interferometer. [Preview Abstract] 

W1.00145: Progress Toward Buffer Gas Cooling of a 1 $\mu_B$ Species Cort Johnson, Bonna Newman, Nathan Brahms, Robert DeCarvalho, ChihHao Li, Tom Greytak, Dan Kleppner, John Doyle Thermalization with a nonmagnetic $^3$He buffer gas has been demonstrated to be an effective means of removing heat from a sample of hot magnetic atoms held in a magnetic trap[1]. To thermally isolate the atoms, it is necessary to remove the buffer gas without sweeping away the magnetically trapped atoms. The magnetic trap strength is proportional to the magnitude of the atom's moment. This is the primary reason that trapping a 1 $\mu_B$ species has never been realized in a buffer gas cooling experiment. Eventually, we plan to use this technique to trap and cool atomic hydrogen and deuterium. We have built a cryogenic valved cell suspended from a dilution refrigerator along the axis of a 4T quadrupole magnetic field. The cell is maintained at a base temperature of 100mK. The buffer gas is removed by opening the valve. Any remaining buffer gas may be energetic enough to scatter the atoms out of the trapping potential, thus limiting the lifetime. Therefore, we lower the temperature of the cell to decrease the vapor pressure of any $^3He$ remaining on the walls. We can mimic the conditions of a 1 $\mu_B$ species using atomic Mn (5 $\mu_B$) simply by lowering the trapping field strength by a factor of five. Further, we will report on efforts to trap and thermally isolate $^7$Li, a true 1 $\mu_B$ species. \\ \noindent [1]J. D. Weinstein et al., Phys.\ Rev.\ A {\bf57}, R3173 (1998). \\ [Preview Abstract] 

W1.00146: Experimental Analogy to TimeIndependent Solutions to Schr\"{o}dinger's Equation: A Level Splitting Approach to Phononic Band Gaps Shawn Hilbert, Noah Weiss, Herman Batelaan A delta barrier inside an infinite potential well is the usual starting point for discussing level splitting, avoided crossings, and band gaps. These same phenomena are found in physical systems such as electronic conductors/insulators and photonic crystals. Here, we explore another physical systema continuous sound wave propagating through an array of partially reflecting acoustic mirrors. We show, experimentally and by calculation, that for the above system, the following general description holds. When two identical acoustic cavities are brought into each other's vicinity, a weak coupling between the two initially degenerate states (i.e. resonant frequencies) gives rise to level splitting. Adding a third identical cavity results in a triplet of states and so on. For an array of identical cavities, a onedimensional crystal lattice forms where the multiplet merges into a band of states. These bands are separated by phononic band gaps. [Preview Abstract] 

W1.00147: Toward Ultracold Atomic Hydrogen and Deuterium: An Application of Buffer Gas Cooling Bonna Newman, Cort Johnson, Nathan Brahms, Robert DeCarvalho, ChihHao Li, Tom Greytak, Dan Kleppner, John Doyle Ultracold samples of atomic H and D offer unique possibilities for precision spectroscopy and studies of quantum fluids. Current techniques to cool H are limited by the small HH elastic scattering cross section and require a superfluid He film in the initial thermalization. The film limits the optical access to the trapped atoms and precludes trapping of D due to high recombination rates on superfluid He films. We have built an apparatus that will use the technique of buffer gas cooling to thermalize 1 $\mu_B$ atoms. Ablation of a solid LiH(LiD) target will produce atomic Li and H(D). Initial thermalization will be achieved through elastic collisions with a $^3$He buffer gas at $\sim$350mK. The large LiH elastic scattering cross section will enhance evaporative cooling of the H atoms. As a first step in this process, we are currently optimizing the system for trapping and cooling of atomic $^7$Li. [Preview Abstract] 

W1.00148: Spinor dynamicsdriven formation of a twinbeam atom laser Nathan Lundblad, David Aveline, Robert J. Thompson, Lute Maleki We demonstrate a novel twinbeam atom laser formed by outcoupling oppositely polarized components of an $F=1$ spinor BoseEinstein condensate whose Zeeman sublevel populations have been coherently evolved through spin dynamics. The condensate is formed initially through alloptical means using a singlebeam runningwave dipole trap. We initially form a condensate in the fieldinsensitive $m_F=0$ state, and drive coherent spinmixing evolution through adiabatic compression of the initially weak trap. Such twin beams, nominally numbercorrelated through the angular momentumconserving reaction $2m_0\leftrightarrow m_{+1}+m_{1}$ have been proposed as tools to explore entanglement and squeezing in BoseEinstein condensates. The twin beams are outcoupled from the opposite ends of a cigarshaped trap; we compare observed images with the behavior of a singlespecies version outcoupled in the direction of gravity. [Preview Abstract] 

W1.00149: Ionization of Xe using Femtosecond Optical Vortices James Strohaber, Igor Mariyenko, Cornelis Uiterwaal Photons in optical vortices possess optical \textit{orbital} angular momentum$^{2}$. What role this quantity plays in ultrafast intensefield processes is to the best of our knowledge experimentally unexplored territory. Using homemade laseretched line holograms (with about 10 grooves per mm), we have recently created femtosecond optical vortices that are sufficiently intense to ionize Xe atoms. The simplest vortices we create are LaguerreGaussian modes with radial mode number $p$ = 0 and azimuthal mode number $l$ = 1 (a.k.a `donut mode'). In 2005, we were the first to report the generation of a (weaker) pure femtosecond vortex.$^{3}$ Using our timeofflight ion mass spectrometer with confined detection volume we plan to spatially image ion clouds generated by focused vortices. Recent progress will be discussed. Refs: $^{2}$Allen L \textit{et al.} 2003 \textit{Optical Angular Momentum} (Bristol: IoP Publ.); $^{3}$Mariyenko I \textit{et al.} 2005 \textit{Opt. Expr.} \textbf{13} 7599. [Preview Abstract] 

W1.00150: Stark Wave Packets in the Heavy Rydberg System H$^{+}${\ldots}F$^{}$ R.C. Shiell, E. Reinhold, F. Magnus, W. Ubachs Heavy Rydberg systems are unusual molecules that comprise a weaklybound anion and cation orbiting their center of mass. Due to a combination of their size and simple internal structure these molecules represent novel systems with which to study molecular dynamics and lightmolecule interactions. We report the formation and control of the weaklybound H$^{+}$..F$^{}$ system by exciting HF molecules using a 1 XUV + 1 UV excitation scheme in an electric field. By using a narrowband laser pulse for the second step, Stark wave packets are formed that evolve in the DC field. A ramped, zerocrossing electric field pulse applied after a variable time delay results in fragment ions arriving at the detector at two distinct times, corresponding to products from two different dissociation channels. By increasing the delay time, these channels alternate in intensity with a period that agrees perfectly with the expected Stark oscillation frequency.\footnote{R. C. Shiell, E. Reinhold, F. Magnus and W. Ubachs, ``Control of diabatic vs adiabatic field dissociation in a heavy Rydberg system,''\textit{ Phys. Rev. Lett.} \textbf{95}, 213002 (2005)} This study verifies the massscaling of heavy Rydberg systems and the viability of these novel molecular systems for further wave packet studies. [Preview Abstract] 
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