Bulletin of the American Physical Society
50th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics APS Meeting
Volume 64, Number 4
Monday–Friday, May 27–31, 2019; Milwaukee, Wisconsin
Session S01: Poster Session III (4:00pm-6:00pm) |
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Room: Wisconsin Center Hall A |
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S01.00001: COLLISIONS AND SPECTROSCOPY |
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S01.00002: Simultaneous determination of rotational and vibrational temperatures in microwave plasma torch operating in Ar or Air/Ar mixtures using optical emission spectroscopy. Sebastien Rassou, Alain Piquemal, Nofel Merbahi, Frederic Marchal, Mohammed Yousfi A microwave (MW) plasma torch is considered to produce plasma at Non local thermodynamic equilibrium (Non-LTE). When the electronic density is not too high the plasma can be considered optically thin. In these assumptions, optical emission spectroscopy can be performed to determine plasma parameters as the temperatures or the species density. A specific method to determine the rotational (Tr) and vibrational temperatures (Tv) using molecular nitrogen second positive system (SPS) emission spectroscopy is presented. It was tested on experimental emission spectra collected from a MW plasma torch operating in gas conditioning cell at 950 mbar with Argon/Air mixtures under different input MW powers and gas flows. From synthetic spectra generated by the line by line radiation code SPARTAN, two coefficients calculated from emission peaks intensities ratio are tabulated as a function of Tr and Tv. The two coefficients are calculated from experimental spectra to determine simultaneously Tr and Tv from the tabulation. The results are validated with comparisons between experimental spectra and synthetic spectra. The present method can be easily generalized to other molecular emission systems for the temperature measurements of non-thermal plasmas generated in different gas mixtures. [Preview Abstract] |
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S01.00003: Absolute single photoionization cross section measurements of isoelectronic Br$^{\mathrm{3+}}$ and Rb$^{\mathrm{5+}}$ ions Jay Evans, Kyren Bobolub, Allison Mueller, Alejandro Aguilar, A.L. David Kilcoyne, Rene Bilodeau, Manuel Bautista, Austin Kerlin, Nicholas Sterling, David Macaluso Absolute single photoionization cross-section measurements of Br$^{\mathrm{3+}}$ and Rb$^{\mathrm{5+}}$ ions were performed using synchrotron radiation and the photo-ion, merged-beams technique at the Advanced Light Source at Lawrence Berkeley National Laboratory. Measurements of Br$^{\mathrm{3+}}$ were performed at a photon energy resolution of 21 meV $+$/- 3 meV from 44.79 -- 59.54 eV spanning the $^{\mathrm{3}}$P$_{\mathrm{0\thinspace }}$ground state and $^{\mathrm{3}}$P$_{\mathrm{1,2}}$ and $^{\mathrm{1}}$D$_{\mathrm{2\thinspace }}$metastable state ionization thresholds. Analysis of the measured spectrum produced a new empirical determination of the ionization potential of Br$^{\mathrm{3+}}$ of 46.977 $+$/- 0.050 eV, which is 805 meV lower than the most recently published value. Measurements of Rb$^{\mathrm{5+}}$ were made at a nominal photon energy resolution of 25.0 meV from 76.62 to 100.07 eV spanning the $^{\mathrm{3}}$P$_{\mathrm{0\thinspace }}$ground state and $^{\mathrm{3}}$P$_{\mathrm{1,2}}$, $^{\mathrm{1}}$D$_{\mathrm{2\thinspace }}$and $^{\mathrm{1}}$S$_{\mathrm{0\thinspace }}$metastable state ionization thresholds. Autoioniziation resonance series idmtifications and quantum defect behavior are compared between the systems and the results of Br$^{\mathrm{3+}}$ are compared to theory. [Preview Abstract] |
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S01.00004: Semiclassical treatment of high-lying electronic states of H$_2^+$ and an approach for computing electronic spectra of long-range diatomic Rydberg molecules Chris H. Greene, T. J. Price A comparison between quantum mechanical and semiclassical WKB calculations for energies and wave functions of high-lying $^2\Sigma$ states of H$_2^+$ is presented. Some of the states shown lie in an unexplored regime, corresponding asymptotically to H$(n\leq 145)$ plus a proton, with $R\leq 120,000$ $a_0$. For all but the lowest lying states, reasonable agreement with quantum mechanical results is obtained by using a straightforward WKB approximation that neglects some barrier effects; these semiclassical calculations are about two orders of magnitude faster than the quantum calculations. In addition, a method is presented in which electronic states of H$_2^+$ are used as a starting point for calculating long-range potential energy curves of diatomic Rydberg molecules with charged atomic cores. This method utilizes the fact that the Rydberg electron moves in a two center Coulomb potential when it is well outside of both cores. Interactions between the Rydberg and core electrons mix in irregular wave functions of H$_2^+$; these effects are incorporated via the Green's function for H$_2^+$ and the quantum defects associated with each atom. [Preview Abstract] |
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S01.00005: Production and exploration of Rydberg highly charged ions S. J. Bromley, E. Takacs, J. P. Marler Highly Charged Ions (HCIs) may be considered ideal mini-laboratory in which one can study the physics of matter and light in an environment of high internal electric field that can not be recreated with standard lab equipment. Rydberg Highly Charged Ions (RyHCI) in which a single electron occupies a high principle quantum number state, in particular, provide excellent test beds for precision measurements of fundamental constants, quantum electrodynamics, and precision X-ray wavelength standards. Even though these systems are highly desirable, the formation of such extreme electronic states is not straightforward due to excitation energies that are many orders of magnitude higher than that of ordinary laser accessible transitions. We will create HCI beams of different kinetic energies at the Clemson University Electron Beam Ion Trap (CUEBIT) facility and intersect them with different neutral atoms of a gas jet target. High-resolution and broadband X-ray spectrometers will be used to observe transitions directly to the ground state simultaneously with alternative cascade channels. [Preview Abstract] |
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S01.00006: Thermophoretic Levitation of Generic Materials Connor Fieweger, Cheng Chin, Joey He, Michelle Chong We report the stable levitation of novel materials through the use of thermophoresis under vacuum. While previous experiment was limited to mostly point-like, solid particles, we now realize levitation of liquid water and porous paper through the use of two newly constructed levitation vacuum chambers. Water droplet mass is calculated from recorded radii of the droplets through absorption imaging and this mass is compared to theoretical prediction for the mass of a stably levitated particle, where good agreement is found. The behavior of 2-dimensional sheets and 3-dimensional folded structures of porous paper is reported in order to inform future theory describing thermophoretic effects on non-spherical objects, which is yet to be developed. [Preview Abstract] |
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S01.00007: CI- MBPT calculations of the iodine line strengths Dmytro Filin, Igor Savukov, James Colgan Iodine is a promising alternative to expensive xenon as propellant for electric propulsion devices. Iodine optical spectroscopy is a valuable diagnostic tool for optimization of the iodine propellant. Recently, some measurements have been conducted with cells containing iodine plasma, and iodine atomic absorption at several wavelengths (911 nm, 906 nm, 206 nm, 1315 nm) was measured with a Ti:Sa laser. Motivated by these experiments and future applications, we have calculated energy levels and line strengths for the iodine atom using configuration-interaction many-body perturbation theory (CI-MBPT). Since no transition data are available for iodine in the literature, we also performed calculations for Br I atom, which has some data, and found good agreement between our theory and the experiment. In iodine, the CI-MBPT gives energies in good agreement with experiment, and we believe that our predicted transition probabilities are also quite reliable and will be useful for iodine spectroscopy. [Preview Abstract] |
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S01.00008: Time-correlated single-photon counting technique to measure lifetime of the Na$_2$ $6\,^1\Sigma_g^+ (7,31)$ state Dinesh Wagle, Michael Saaranen, Emma Mclaughlin, Amelia Paladino, Seth Ashman, Burcin Bayram We report on the lifetime measurement of the $6\,^1\Sigma_g^+ (7,31)$ state of sodium molecules using a time-resolved spectroscopic technique [1]. The $6\,^1\Sigma_g^+ (7,31)$ state was populated by double-resonance excitation via the intermediate $A\,^1\Sigma_u^+ (8,30)$ state. This was accomplished by two synchronized pulsed lasers pumped by a Nd:YAG laser operating at the second harmonics. The molecular fluorescence emitted from the final state was collected and the lifetime was measured from the $v$=6 doublet using a time-correlated single-photon counting technique, as a function of argon pressure. From this, the radiative lifetime was extracted by extrapolating the plot to collision-free zero pressure. We compared our results with the calculated radiative lifetimes in the range of $v$=0-200 with $J$=1 and $J$=31. The results also reveal the importance of the bound-free transitions and the rotational quantum number dependence on the lifetime calculations. The measured and calculated radiative lifetimes are found to be 39.56~($\pm$ 2.23) ns and 42.8 ns, respectively. Ref.[1] Saaranen $\textit{et al.}$, JCP $\textbf{149}$, 204302 (2018). [Preview Abstract] |
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S01.00009: Lifetime Calculations of Selected Ro-Vibrational Levels of the $6^{1}\Sigma _{g}^{+} $ State of the $Na_{2} $ Dimer and Comparison to Experiment Seth Ashman, S. Burcin Bayram, Emma McLaughlin, Amelia Paladino, Michael Saaranen, Dinesh Wagle Lifetimes of ro-vibrational levels of the $6^{1}\Sigma_{g}^{+} $ state of $Na_{2} $ have been calculated using best available potential energy curves of relevant molecular states and transition dipole moment functions. The Level program by Le Roy has been used to calculate Einstein coefficients of transitions from selected $6^{1}\Sigma_{g}^{+} $ ro-vibrational levels in the range $v=$0-200 with $J=$1 and $J=$31 to all dipole allowed ro-vibrational levels of the $1\left( A \right)^{1}\Sigma_{u}^{+} $, $1\left( B \right)^{1}\Pi_{u} $, $2^{1}\Sigma_{u}^{+} $, $3^{1}\Sigma_{u}^{+} $, $2^{1}\Pi_{u} $, $4^{1}\Sigma_{u}^{+} $, $3^{1}\Pi_{u} $ states. Bound-free transitions have been calculated using the BCont program, and the outputs of these two programs are combined to determine the radiative lifetimes of selected $6^{1}\Sigma_{g}^{+} \left( {v,J} \right)$ levels. Comparison to experimentally measured lifetimes shows favorable agreement. We have applied a similar computational approach to determine radiative lifetimes of ro-vibrational levels of the $2^{1}\Sigma_{u}^{+} $ and $4^{1}\Sigma_{u}^{+} $ states of $Na_{2} $, yielding good agreement with experimentally determined lifetimes, and we note this approach could be applied to other systems for which reliable potential energy curves and transition dipole moment data is available. [Preview Abstract] |
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S01.00010: Precision spectroscopy in neutral beryllium-9 Eryn Cook, Lucy Lin, Esther Kerns, Chelsea Perez, Will Williams We report on spectroscopic measurement progress for a variety of states in neutral beryllium-9. We are exploring resonantly-enhanced two-photon spectroscopy for improved absolute frequency determination of the $2s2p\,^1P_1$ and $2s3d\,^1D_2$ states. Progress toward combination optical / ionization spectroscopy for improved measurement of the absolute frequency of the $2s2p\,^3P_1$ state and the ionization threshold will also be presented. [Preview Abstract] |
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S01.00011: Theoretical study of valence and k shell double photoionization of Magnesium atoms using affective charge approximation. Haripada Saha We plan to report the results of our investigation on theoretical study of electron correlation in the double photoionization of valence and K-shell electrons from Magnesium atoms. We will present the results of triple differential cross sections using our recently extended MCHF method [1]. We will use multiconfiguration Hartree Fock bound state method to calculate the wave functions for the initial state., which includes the electron correlation effect completely ab-initio. The final state continuum wave functions will be calculated using the angle depended Effective Charge approximation [2-4] which accounts for electron correlation between the two final state continuum electrons. We will discuss the effect of core electron correlation on the double valence shell ionization and valence electrons correlation on the double k-shell ionization in the triple differential cross section. The results will be compared with the available accurate theoretical calculations and experimental findings. [1] Hari P. Saha, Phys. Rev. A 87, 042703 (2013); Phys. Rev. A 95, 063423 (2017) [2] M.R.H. Rudge, Rev. Mod. Phys. 40, 564 (1968). [3] D. Proulox and R. Shakeshaft,, Phys. Rev A 48, R875 (1993). [4]; M. Pont and R. Shakeshaft, Phys. Rev. A51, R2676 (1995). [Preview Abstract] |
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S01.00012: Outer-shell photodetachment of Li- in the vicinity of inner-shell thresholds T. W. Gorczyca, S. T. Manson Recent work has shown that the photoionization of outer shells of atoms are profoundly affected by correlation in the form of interchannel coupling in the vicinity of inner-shell thresholds [1,2]. Since negative ions, by their very nature, are much more highly-correlated than atoms, it is expected that these effects should be even more pronounced in negative ion photodetachment. Thus, we have started a program to explore this effect, and we have looked at the photodetachment of the simplest closed-shell negative ion with more than one shell, Li- in the ground 1s22s2 state, using a version of the Belfast R-matrix methodology that has been modified to accommodate photodetachment [3]. The results show that the outer-shell photodetachment cross sections leading to the ground state 1s22s state of Li, along with a number of excited 1s2nl states (detachment plus excitation), are indeed very strongly altered owing to the interchannel coupling with the inner-shell photodetachment channels. Work supported partially by the NASA and DOE. [1] W. Drube, et al, J. Phys. B 46, 245006 (2013); [2] D. A. Keating, et al, Phys. Rev. A 98, 013420 (2018); [3] T. W. Gorczyca, et al, Phys. Rev. A 68, 050703(R) (2003). [Preview Abstract] |
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S01.00013: Photoionization of halogen atoms and singly-charged halogen anions @C$_{\mathrm{240}}$ Ruma De, Dakota Shields, Steven T. Manson, Himadri Chakraborty The ground states of endofullerene molecules comprised of one-vacancy open-shell halogen atoms and closed-shell singly-charged halogen anions confined in the C$_{\mathrm{240}}$ fullerene are modeled in a spherical Kohn-Sham local density approximation (LDA). The framework is augmented by the Leeuwen and Baerends exchange-correlation functional [1]. The core of two hundred and forty C$^{\mathrm{4+}}$ ions is jelliumized [2] to ignore the carbon $K$-shell structures. A time-dependent LDA (TDLDA) method [3] is subsequently applied to calculate the photoionization parameters of the molecules in the dipole interaction frame. The cross sections of various levels of the molecules, in comparison with the results of free atom/anion as well as empty C$_{\mathrm{240}}$, display two general spectral regions: (i) plasmon resonance enhanced low-energy domain and (ii) higher energy region of broad oscillations from the coherence of fullerene cavity and confinement effects. The results show differences in transitioning from neutral to anionic state of the central species in C$_{\mathrm{240}}$. Further comparisons with corresponding calculations of C$_{\mathrm{60}}$ endofullerenes unravel effects of the size and electronic configuration of the fullerene cage. [1] R. van Leeuwen et al, Phys. Rev. A \textbf{49}, 2421 (1994); [2] M. E. Madjet et al., Phys. Rev. A \textbf{81}, 013202 (2010); [3] Choi et al., Phys. Rev. A \textbf{95}, 023404 (2017). [Preview Abstract] |
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S01.00014: Low-Energy Scattering Properties of Ground-State and Excited-State Positronium Collisions Michael D. Higgins, Kevin M. Daily, Chris H. Greene Low-energy elastic and inelastic scattering in the Ps(1s)-Ps(2s) channel is treated in a four-body hyperspherical coordinate calculation. Adiabatic potentials are calculated for triplet-triplet (TT), singlet-singlet (SS), and singlet-triplet (ST) spin symmetries in the spin representation of coupled electrons ($S_-$) and coupled positrons ($S_+$), with total angular momentum $L=0$ and charge conjugation and parity both equal to $+1$. Multichannel scattering calculations were performed to obtain preliminary estimates of the $s$-wave scattering length in the asymptotic Ps(1$s$)-Ps(2$s$) channel for each spin configuration. Spin re-coupling is implemented to obtain scattering lengths and cross-sections for collisions of Ps atoms in different spin configurations through properly symmetrized unitary transformations. Calculations of experimentally relevant scattering lengths and cross-sections are carried-out for collisions with total spin, $S_{\mathrm{tot}}=0$, $1$, and $2$. [Preview Abstract] |
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S01.00015: Engineering long-range interactions between high-$n$, $n \ge $ 300, strontium Rydberg atoms in a beam Robert Fields, Robert Brienza, F.B. Dunning, Shuhei Yoshida, J. Burgdorfer In the present work the control of long-range interactions between strontium atoms in very high-n, n $\ge $ 300, Rydberg states is being examined using an atomic beam. Pairs of Rydberg atoms are initially created, under blockade conditions with well-defined initial separations in localized volumes defined by focused laser beams. Their subsequent interactions are manipulated by using a carefully-tailored series of pulsed electric fields to excite the atoms to selected (more-strongly-interacting) higher-n states, the degree of interaction being controlled through the choice of final state and the initial atom pair separation. Long-range interactions lead both to collisional destruction and to state changing, which are monitored by selective field ionization and by application of further pulsed fields. The results are analyzed using classical trajectory Monte Carlo simulations and demonstrate not only the control of Rydberg-Rydberg interactions but also their long-range. [Preview Abstract] |
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S01.00016: Magnetic-field stability in unshielded Helmholtz coils David P. Morin, Sheng Zou, Chamithri Adikarige, Zahra Armanfard, Trevor Foote, Brian Saam Many table-top AMO experiments require magnetic field stability, {\it e.g.}, for precise measurement of resonance frequencies and shifts. This is often achieved with a very small or nominally zero field, where the entire apparatus is shielded with several layers of expensive mu-metal. Spin-exchange optical pumping (SEOP), by contrast, practically requires a larger (tens of gauss) field that defines a lab quantization axis and mitigates low-field spin-relaxation effects. We routinely stabilize unshielded Helmholtz coils to better than a part in 10$^5$ at 30~G in an $\approx 10$~Hz bandwidth, and achieve a few parts in 10$^6$ late at night with less external interference [1]. In this work, we compare several stabilization techniques based on driving the inductive load with a commercial (CV/CC) power supply, including: using the supply in current-control mode (worst result); and using it in voltage-control mode coupled with one or more of: (1) a stable sensing resistor in series with the coils, (2) an external comparator driving the gate of a FET in series with the coils, and (3) the output voltage generated by a commercial magnetometer fed directly to the power supply sensing inputs. [1] A. Nahlawi {\it et al.}, in prep.; see poster by S. Zou {\it et al.}, at this conference. [Preview Abstract] |
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S01.00017: Co-trapped heteronuclear Rydberg and Collisional Interactions in an Optical Dipole Trap Matthew Ebert, Cody Poole, Xiaoyu Jiang, Genevieve Kearns, Eite Tiesinga, Mark Saffman We present progress in demonstrating Rydberg interactions between a single Rb and a single Cs atom simultaneously trapped in a single 1064 nm optical tweezer. Rydberg levels in heteronuclear systems have different quantum defects, as opposed to homonuclear systems, and can therefore be chosen to minimize the Forster defect and increase the Rydberg interaction strength beyond symmetric Rydberg pairs at comparable energy levels. Additionally, multi-species systems are distinguishable and can be frequency multiplexed in a straightforward manner, enabling crosstalk free ancilla measurements for quantum error correction. To determine the feasibility of co-trapped heteronuclear samples for quantum information and communication applications, we also measure the heteronuclear collision rates between single Rb and single Cs atoms and resolve differences in the hyperfine collision rates. Photoassociation rate of the atoms into a molecular state via the 1064 nm trap laser is also measured. [Preview Abstract] |
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S01.00018: State resolved investigation of F\"orster resonant energy transfer in collisions between polar molecules and Rydberg atoms Martin Zeppenfeld, Ferdinand Jarisch Investigation of collisions between molecules and Rydberg atoms provides access to a wide range of interesting processes, including, e.g., molecule-ion collisions, ionization, and electron capture. A particular fascinating aspect results from coincidences between the energy spacing of molecular rotational states and Rydberg states, leading to F\"orster resonant energy transfer between the two systems.\\ Combining state selective field ionization of Rydberg atoms with millimeter-wave state transfer allows us to perform fully state resolved measurements of Rydberg-atom populations. This allows us to investigate energy transfer between ammonia molecules and rubidium Rydberg atoms in detail~[1]. Varying the Rydberg atom transition frequency by changing the initial Rydberg state and tuning the transition with electric fields allows us to investigate the depence of the resonant energy transfer on the resonance condition. Examining the populations of different Rydberg angular momentum states including different M-sublevels allows us to study angular momentum selection rules for the molecule-Rydberg-atom interactions.\\ \noindent[1] F. Jarisch {\it et al.} NJP {\bf 20}, 113044 (2018) [Preview Abstract] |
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S01.00019: Electron Impact Ionization of W+ S. D. Loch, M. S. Pindzola Electron-impact single and double ionization cross sections for the W+ atomic ion are calculated using a combination of time-dependent close-coupling and time-independent distorted-wave methods. Direct ionization of the 6s and 5d subshells dominates the single ionization cross section, while direct ionization of the 4f and 5p subshells dominates the double ionization cross section. The cross sections for W+ are compared with crossed-beams measurements. [Preview Abstract] |
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S01.00020: A multipass laser system for free-free experiments C.M. Weaver, B.N. Kim, N.L.S. Martin, B.A. deHarak A multipass laser system is being developed for an electron scattering apparatus that will be used for laser-assisted free-free electron scattering experiments. The basic idea is that a gated Pockels cell is used to rotate horizontally polarized light, in an injection mode, to vertically polarized light which is then trapped in a repetitive path using mirrors and a polarizing beam-splitter cube. A test bed has proved the feasibility of this technique: 20 passes have been observed with a 20\% loss per round trip; this would correspond to in an increase of a factor of 5 in data collection. The system is now being installed on the scattering apparatus with similar initial results; we will present a progress report on this multipass system. We hope to increase the efficiency of the system so that there is only 10\% loss per round trip in order to achieve an order of magnitude improvement in data collection compared to that of a single pass set up. [Preview Abstract] |
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S01.00021: Binding energies of ground state negative ion formation in large lanthanide atoms Ho, Er, Tm, Yb and Lu Alfred Z Msezane, Zineb Felfli The robust Regge-pole methodology wherein is fully embedded the essential electron-electron correlation effects and the vital core polarization interaction has been used to explore negative ion formation in the lanthanide atoms Ho, Er, Tm, Yb and Lu through the electron elastic scattering total cross sections (TCSs) calculations. The TCSs are found to be characterized generally by Ramsauer-Townsend (R-T) minima, shape resonances and dramatically sharp resonances manifesting ground and metastable anionic formation during the collisions. The extracted ground state anionic binding energies (BEs) from the TCSs for Ho, Er, Tm, Yb and Lu are 3.51 eV, 3.53 eV, 3.36 eV, 3.49 eV and 4.09 eV, respectively. The novelty and generality of our approach is the extraction of the electron affinities (EAs) of complex heavy atoms from the anionic ground state BEs calculated through the electron TCSs. For Au and Pt atoms as well as C$_{\mathrm{60}}$ fullerene the BEs yielded outstanding match with the measured EAs. The investigation has been motivated by: 1) The experiment [1] searched in vain for the EA of Yb and concluded that it must be less than 3 meV; 2) For the Tm atom the measured EA value of 1.029 eV [2] agrees excellently with our anionic excited state BE of 1.02 eV. In [3] it has been concluded that theoretical calculations incorrectly identified the BEs of the metastable/excited anions with the EAs of the actinide atoms. 1. H. H. Andersen, et al., J. Phys. B \textbf{31}, 2239 (1998); 2. V.T. Davis and J.S. Thompson, Phys. Rev. A \textbf{65}, 010501 (R) (2001); 3. Z. Felfli and A. Z. Msezane, Applied Physics Research Vol. \textbf{11}, No. 1; 2019 ISSN 1916-9639 (2019) [Preview Abstract] |
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S01.00022: Negative ion formation in fullerene molecules C$_{\mathrm{44}}$, C$_{\mathrm{74,\thinspace }}$C$_{\mathrm{100}}$ and C$_{\mathrm{136}}$: determination of their electron affinities Alfred Z Msezane, Zineb Felfli In the context of fullerene negative ion catalysis, fullerenes for organic solar-cells, sensor technology, etc. here we investigate the variation of the electron affinity (EA) with the fullerene size from C$_{\mathrm{44}}$ to C$_{\mathrm{136}}$ and contrast their EAs with that of C$_{\mathrm{60}}$. In fullerene molecule negative ion formation, it has been demonstrated for the first time that the ground state anionic binding energies (BEs) extracted from our Regge-pole calculated electron elastic scattering total cross sections (TCSs) for the C$_{\mathrm{20}}$ through C$_{\mathrm{92}}$ fullerenes matched excellently the measured EAs of these fullerenes [1, 2]. The Regge-pole methodology requires no assistance whatsoever from either experiment or other theory for the remarkable feat. This provides a novel approach to the determination of reliable EAs for complex heavy systems. Here we have used the robust Regge-pole methodology to investigate negative ion formation in the fullerenes C$_{\mathrm{44}}$, C$_{\mathrm{74}}$, C$_{\mathrm{100}}$ and C$_{\mathrm{136}}$ through the low-energy electron elastic TCSs calculations. The TCSs are found to be characterized generally by Ramsauer-Townsend minima, shape resonances and dramatically sharp resonances manifesting ground and metastable anionic formation during the collisions. The extracted ground state anionic binding energies (BEs) from the TCSs for C$_{\mathrm{44}}$, C$_{\mathrm{74}}$, C$_{\mathrm{100}}$ and C$_{\mathrm{136}}$ are 3.25eV, 4.03eV, 3.67eV, 3.75eV, respectively. These correspond to the EAs of the fullerene molecules and demonstrate the wide variation from fullerene to fullerene. The BEs will be contrasted with those of the standard C$_{\mathrm{60}}$ and other fullerenes as well. 1. A. Z. Msezane and Z. Felfli, Chem. Phys. \textbf{503}, 50 (2018); 2. Z. Felfli and A. Z. Msezane, Euro Phys. J. D \textbf{72,} 78 (2018) [Preview Abstract] |
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S01.00023: Charge Transfer in Mg+12 + H Collisions M. S. Pindzola, M. Fogle A time-dependent lattice method is used to calculate state selective charge transfer cross sections in Mg+12 collisions with H atoms. Mg+11 (nl) capture cross sections are obtained for n = 1,9 at incident energies of 1.0, 3.0, and 5.0 keV/amu. Using standard radiative transition rates, Lyman line ratios are calculated in support of Clemson CUEBIT experiments. [Preview Abstract] |
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S01.00024: Towards Velocity Map Imaging from an Ion Trap Elizabeth West, Grant Mitts, Prateek Puri, Eric Hudson Velocity map imaging (VMI) is a versatile tool for studying molecular structure and chemical reaction dynamics by mapping the kinetic energy distributions of charged particles onto position space. In standard ion VMI, experiments (e.g. gas-phase collisions with a reaction partner) are performed on initially neutral species. The species are then ionized in the presence of uniform static electric fields which accelerate them towards an imaging detector. Starting with neutrals provides immunity to fields in the VMI acceleration region during the initial experiment. However, the ability to expand the technique to trapped cations would open up new realms of interesting chemistry and bring to bear the many well established advantages of ion traps, including long interaction times, single-particle addressability, and the possibility of laser and sympathetic cooling to the ultracold regime. We describe progress towards realizing a new type of VMI apparatus, in which the species of interest are initially ionic. These ions are trapped in a linear quadrupole trap before being ejected towards the detector by carefully controlled high-voltage pulses applied to the trap rods. [Preview Abstract] |
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S01.00025: Variational Calculations of the Ps-Ps System Gabriel Medrano, S. J. Ward, P. Van Reeth Knowing the value of the o-Ps--o-Ps scattering length has enabled it to be shown that it is possible to create a Ps Bose-Einstein Condensate [1,2]. We intend to use the Kohn and inverse Kohn variational methods to calculate accurately the scattering length and phase shifts for o-Ps--o-Ps scattering, which is a four-body scattering system made entirely of leptons. These two methods, with flexible trial functions, have provided accurate results for other four-body scattering systems, such as Ps-H scattering [3]. We have determined the ground-state energy and binding energy of Ps$_2$ using the Rayleigh-Ritz variational method with a short-range interaction trial wave function [4]. We plan to investigate the variation of the energies with different trial wave functions. \begin{enumerate} \item E. P. Liang, C. D. Demer, Opt. Commun. {\bf 65}, 419 (1998) \item P. M. Platzman, A. P. Mills, Jr., Phys. Rev. B {\bf 49}, 454 (1994) \item D. Woods, S. J. Ward, P. Van Reeth, Phys. Rev. A {\bf 92}, 022713 (2015) \item Y. K. Ho, Phys. Rev. A {\bf 33}, 3584 (1986) \end{enumerate} [Preview Abstract] |
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S01.00026: New measurements of positron annihilation on molecules using an enhanced energy-resolution trapped based beam. J. R. Danielson, S. Ghosh, C. M. Surko Experiments have shown that low-energy (sub eV) annihilation spectra of positrons on molecules are typically dominated by relatively sharp features that have been identified as vibrational Feshbach resonances (VFR) involving fundamental modes. Further, in most molecules there is a broad spectrum of enhanced annihilation between the fundamentals, in the region of combination and overtone vibrational modes, where the density of modes is typically too high to identify discrete modes. Ultimately, the experimental resolution of the spectrum is dependent on the energy resolution of the positron beam. Over the last several years, we have made a number of advancements in understanding the factors limiting the energy resolution of trapped based positron beams. Experiments demonstrating the effect of increased resolution on the measured annihilation spectra will be presented. Prospects for clarifying the role of combination and overtone modes in the broad background spectrum will also be discussed. [Preview Abstract] |
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S01.00027: Tracing Plasma Produced Atomic and Molecular species from Plasma into the Liquid and Living tissue for various applications Zoran Petrovic, Nikola Skoro, Suzana Zivkovic, Milica Milutinovic, Olivera Jovanovic, Nenad Selakovic, Nevena Puac Significant effects observed in applications of atmospheric pressure non-equilibrium plasmas have been shown to be due to the effect of plasma produced atomic and molecular reactive species. Some of those species are the ones acting as signaling agents initiating response of the living cells. At the same time, albeit in larger numbers, they may be chemical agents that can damage or dissociate unwanted living organisms, human cells or chemical components. We try to follow the trail of atomic and molecular physics starting from their formation, their passage into liquids and then passage into living cells or the reaction of cells that they invoke. Two examples will be the long term changes in enzymes regulating hydrogen peroxide in plant cells and destruction of malathion, a pesticide used in agriculture that may be a model of more lethal weapons of mass destruction. Finally we shall illustrate how presence of those active species in plasma treated water affects the germination of seeds. -/abstract- Authors Zoran Lj Petrovic, Nikola Skoro, Suzana Zivkovi\'{c}, Milica Milutinovic, Olivera Jovanovic, Nenad Selakovic, [Preview Abstract] |
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S01.00028: Some Important Early Physics Formulas, Currently Used, Lack Rotation And Vibration Kinetic Energy Factors Which Must Be Included At This Time To Ensure Formula Accuracy Stewart Brekke Every form of matter, from elementary particles, atoms and molecules to planets, stars and galaxies, have no motion, linear, rotational and/or vibrational motion singly or in some combination. Some early formulas o not include all of these possibilities. In 1905 Einstein derived the total energy of a mass at slow speeds to be: ${E=mc^2 + 1/2mv^2}$. However, the total energy must also include the rotation,and vibration kinetic energies and also potential energies. Thus: ${E =mc^2 +1/2mv^2 + 1/2I(\omega)^2 +1/2kx^2 + Gm_1m_2/r +kq_1q_2/r}$. The Photoelectric Effect formula must also be: ${hf=(1/2mv^2 + 1/2I(\omega)^2 + 1/2kx^2)max +\phi}$.The Virial Theorem must also be: ${1/2mv^2 + 1/2I(\omega)^2 +1/2kx^2 +U =0}$ where U is the gravitational potential energy of the body. The Compton Effect equation should be modified to include the change in rotation and vibration kinetic energy of the particle before and after photon impact: ${hc/(\lambda)_1 +(m_0)c^2 +1/2m(v_1)^2 +1/2I((\omega)_1)^2 +1/2k(x_1)^2 = hc/(\lambda)_2 + (m_0)c^2 + +1/2(m_2)v^2 + 1/2I(\omega)_2)^2 +1/2k_2(x_2)^2}$. Many other early created important physics formulas may need to be updated by adding rotation and vibration kinetic energy factors. [Preview Abstract] |
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S01.00029: PRECISION MEASUREMENTS |
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S01.00030: EDM$^3$: Progress towards a new search for the electron electric dipole moment using molecules in a matrix E.A. Hessels, M. Horbatsch, M.C. George, C.H. Storry, G. Koyanagi, R. Fournier, A. Ragyanszki, A. Marsman, H.M. Yau, Z. Corriveau, N. McCall, J. Perez-Garcia, K. Saltoun, J.T. Singh, F. Fry, E. White, A.C. Vutha Improved measurements of the electron electric dipole moment (eEDM) will strongly constrain the parameter space of new physics theories. Over the last decade, polar molecules have become established as the most promising systems for eEDM searches, due to the large internal electric fields experienced by an eEDM in these molecules. The sensitivity of eEDM searches is determined by the coherence time available for measuring eEDM-induced electron spin precession, as well as the total number of molecules available over the course of a measurement. We present our progress in implementing a new method, which combines long coherence times and large molecule numbers, for an eEDM search experiment with significantly improved precision [1]. Our system, involving polar molecules oriented within a rare-gas matrix, also offers an array of reversals and controls for cleanly suppressing systematic effects to a level commensurate with the improved statistical precision. [1] AC Vutha, M Horbatsch, EA Hessels PRA 98, 03251 [Preview Abstract] |
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S01.00031: Towards spectroscopy of heavy molecular ions, including TaO$^{+}$ and RaOH$^{+}$ Craig A. Holliman, Jared Pagett, Mingyu Fan, Paul Hess, Andrew M. Jayich Heavy molecular ions are promising candidates for probing new physics beyond the standard model, but the spectroscopic information for designing experiments is extremely limited. We are pursuing cavity enhanced velocity modulated spectroscopy (CEVMS) of heavy molecular ions to enable precision measurement experiments with molecular ions containing deformed nuclei. Collective effects in such nuclei promise to enhance sensitivity to charge-parity violation arising in the nucleus. We report on progress towards spectroscopy of TaO$^{+}$ and plans to perform spectroscopy on radium-based molecular ions, such as RaOH$^{+}$ and RaOCH$_{3}^{+}$. [Preview Abstract] |
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S01.00032: ABSTRACT WITHDRAWN |
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S01.00033: Search for Axion Stars Using the Global Network of Optical Magnetometers for Exotic Physics (GNOME) Perrin Segura, Madeline Monroy, Tatum Wilson, Christopher A. Palm, Sunyool Park, Jason Mora, Alexander Penaflor, Ibrahim Sulai, Derek Jackson Kimball, Jason Stalnaker Light scalar fields in the form of axion stars or Q-balls are a possible candidate for dark matter. The Global Network of Optical Magnetometers for Exotic physics (GNOME) is sensitive to such compact objects via a coupling of the fields to the atomic and nuclear spins. We present an analysis method for the GNOME data that is sensitive to axion stars and Q-balls based on the excess power technique. We present preliminary results and discuss the sensitivity of such a network to this form of dark matter. [Preview Abstract] |
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S01.00034: ABSTRACT WITHDRAWN |
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S01.00035: Global Network of Clocks and Magnetometers as Exotic Light Field Telescopes Ibrahim Sulai, Conner Dailey, Geoff Blewitt, Andrei Derevianko, Derek Jackson Kimball Exotic bosonic fields are features of many extensions of the standard Model. These hypothetical fields are typically predicted to feebly interact with standard model particles, and thus can both be generated in astrophysical processes and detected with atomic clocks and magnetometers. We consider the sensitivity of existing global clock and magnetometer networks to bursts of such exotic light fields (ELFs). As a proof-of-principle, we analyze data from the clock network comprising the global positioning system and a worldwide network of shielded atomic magnetometers for signals coincident with recently observed binary black hole mergers, neutron star mergers, and fast radio bursts. [Preview Abstract] |
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S01.00036: Heading error analysis of a pulsed $^{\mathrm{87}}$Rb magnetometer at geomagnetic fields Wonjae Lee, Vito Lucivero, Mark Limes, Elizabeth Foley, Thomas Kornack, Michael Romalis In scalar atomic magnetometer operation at geophysical magnetic fields heading errors cause unwanted dependence of the measured field on the orientation of the sensor. We use a pulsed $^{\mathrm{87}}$Rb magnetometer using a short pumping pulse and monitoring of free spin precession to study the dependence of the heading error on the initial spin polarization and on the field orientation with respect to the pump laser. The heading error due to the orientation dependence can be calculated by a simple analytical expression in the limit of high spin polarization. For the polarization dependence, we predict a nonlinear shift in the spin precession frequency as a function of the field at lower spin polarizations. It is due to the nuclear magnetic moment which splits the center frequencies of the two hyperfine manifolds and generates interference between them. We experimentally confirm both of these predictions by carefully making frequency measurements as a function of magnetic field magnitude and angle and by taking into account hysteresis of the magnetic shielding. [Preview Abstract] |
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S01.00037: An all-optical atomic magnetometer-gradiometer for use in Earth's field. Robert Wyllie, Abigail Perry, Thad Walker, Bob Buckley, Gordon Morrison, Michael Bulatowicz, Robert Griffith, Philip Clark, Dennis Bevan, Bo Halamandaris, James Pavell, Michael Larsen We present the design and initial characterization of an all-optical atomic magnetometer and gradiometer. The magnetometer and gradiometer channels utilize pulsed optical pumping synchronous with the Larmor precession of 87Rb atoms, while a co-propagating probe beam reads out both the magnetometer and gradiometer signals. The magnetometer sensitivity is near 200 fT/Hz\textasciicircum 1/2, while the gradiometer sensitivity is below 100 fT/cm/Hz\textasciicircum 1/2 on a 4 cm baseline. We will also present the characterization of the common mode rejection ratio and our approach to mitigating deadzones in the measurement. [Preview Abstract] |
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S01.00038: An optical clock platform with strontium atoms in tweezers Matthew Norcia, Aaron Young, William Eckner, Benjamin Johnston, Adam Kaufman Arrays of strontium atoms trapped within optical tweezers provide an intriguing new platform for optical frequency metrology, with a unique combination of appealing features including relatively large particle numbers, absence of interatomic collisions, long coherence times, and low dead times through repeated lossless imaging. Further, if Rydberg interactions were introduced between the tweezer-trapped atoms, the microscopic control afforded by this system may enable entanglement-enhanced performance. Here, we demonstrate highly coherent excitation of the ultra narrow $^1S_0$ to $^3P_0$ clock transition in arrays of tweezer-trapped $^{88}$Sr atoms, as well as repeated interrogation of the same ensemble of atoms using high-fidelity, low loss measurements. These results provide the key ingredients for a new form of highly capable optical clocks. [Preview Abstract] |
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S01.00039: Towards Optical Frequency Standard based on Lutetium Ion Ting Rei Tan, Rattakorn Kaewuam, Kyle Arnold, Jaren Gan, Gleb Maslennikov, Ko-Wei Tseng, Dzmitry Matsukevich, Murray Barrett A lutetium ($^{176}$Lu$^+$) ion offers multiple advantageous as a promising candidate as an optical frequency standard, these include (i) multiple optical clock transitions, (ii) long excited state lifetimes (up to $\sim$ 1 week), (iii) low sensitivity to magnetic field, (iv) low blackbody-radiation shift, (v) low second-order Doppler shift. Furthermore, it has the prospect of a multi-ion operation working at a ``magic'' radio-frequency (RF) where the two important shifts (i.e. second-order Doppler shift and AC Stark shift) due to micromotion are exactly canceled. Here, we report progress on establishing clock operation on a small linear Coulomb crystal of $^{176}$Lu$^+$. We also present high-accuracy measurements of the 577 nm $^1S_0$ $\leftrightarrow$ $^1D_2$ clock transition from which we extract hyperfine splittings. Hyperfine structure constants associated with the nuclear magnetic octupole and electric hexadecapole (16) moments are considered. An often-overlooked systematic shift due to a transverse AC Zeeman effect associated with the trapping RF is also discussed; an evaluation method based on Autler-Townes splitting is experimentally demonstrated. [Preview Abstract] |
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S01.00040: Improved stability of a 87 Sr three-dimensional optical lattice clock Lingfeng Yan, William Milner, Ross Hutson, Lindsay Sonderhouse, Christian Sanner, Akihisa Goban, Jun Ye Optical clocks with high accuracy and stability play an essential role in a wide range of technological and scientific applications. A ${}^{87}$Sr three-dimensional optical lattice clock has recently demonstrated record-breaking stability due to its large atom number and long coherence time. This performance can be further improved by decreasing the dead time and realizing a longer coherence time. Through improved loading of the optical trap, we have reduced the duration of our evaporative cooling from 10 s to 3 s while maintaining T/T$_{F}$=0.05. We also describe a new optical lattice clock geometry for improving the atomic coherence time that has previously been limited by Raman scattering induced by optical lattice beams. [Preview Abstract] |
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S01.00041: Atom spin gyroscope based on Rb-Xe vapor cell. Sin Hyuk Yim, Sangkyung Lee, Tae Hyun Kim, Zaeill Kim, Kyu Min Shim We present results of atom spin gyroscope (ASG) using dual species of noble gases. The vapor cell contain Rb, $^{\mathrm{129}}$Xe, $^{\mathrm{131}}$Xe, N$_{\mathrm{2}}$, and H$_{\mathrm{2}}$ gases. The magnetic field fluctuation can be reduced by using two Larmor frequencies of 118 Hz and 35 Hz, respectively. We apply parametric modulation of z-axis of magnetic field to extract the $^{\mathrm{129}}$Xe and $^{\mathrm{131}}$Xe signals. The transverse relaxation time of $^{\mathrm{129}}$Xe and $^{\mathrm{131}}$Xe are 70 s and 10 s, respectively. The Angular Random Walk (ARW) of the ASG is 0.98 deg/h$^{\mathrm{1/2}}$ and Bias instability is 5.46 deg/h. Further developments will be made by enriched Xe vapor cell. [Preview Abstract] |
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S01.00042: Synchronous Spin-Exchange Optically Pumped NMR Gyro Daniel Thrasher, Susan Sorensen, Michael Bulatowicz, Thad Walker We present progress toward a dual-species synchronous spin-exchange optically pumped NMR gyro and discuss the leading systematic errors. Xe131 and Xe129 are simultaneously polarized transverse to a pulsed bias magnetic field through spin exchange collisions with polarized Rb atoms. We further discuss driving the Xe precession by modulating the repetition rate of the bias field pulses as an alternative to optical pumping modulation. This allows for large modulation depths while maintaining the fidelity of the embedded Rb magnetometer. [Preview Abstract] |
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S01.00043: Quantum Diamond Microscope for Geosciences and Electronics Raisa Trubko, Matthew Turner, Nicholas Langellier, Roger Fu, Edlyn Levine, Marko Loncar, Amir Yacoby, Ronald Walsworth We present a 'quantum diamond microscope' (QDM) that uses nitrogen-vacancy (NV) defects in diamond for imaging magnetic fields with micron-scale spatial resolution and mm-scale field-of-view for a range of studies in both geosciences and electronics. For the geosciences, the QDM allows us to spatially resolve different ferromagnetic minerals within a rock sample. This capability enables the paleomagnetic study of samples with complex, heterogeneous magnetization, thereby greatly expanding the range of broader scientific questions that can be addressed. For electronics, we can non-invasively monitor the activity of microwave electronics with higher spatial resolution, which is important for moving towards localizing the current flow down to the individual circuit component level. [Preview Abstract] |
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S01.00044: Raman transitions for atomic gravimetry with opposite momentum transfer. Mario Maldonado, Wanderson Maia, Victor Valenzuela, John Franco, Eduardo Gomez An atomic quantum gravimeter, based on Raman transitions, requires two counter-propagating phase-locked light beams with a frequency difference close to the atomic hyperfine splitting. These beams can be generated using an electro-optical modulator that produces sidebands that are automatically phase-locked with the carrier since they all come from a single laser. One problem with this configuration is a destructive interference that appears between the two Raman pairs generated. Using a highly dispersive birefringent material, a calcite crystal in our case, we convert the above interference into a constructive one. The setup gives Raman pairs with Doppler shifts in opposite directions. We use them to excite counter propagating transitions with momentum transfer in two different directions, something that can prove very useful in atomic gravimetry. [Preview Abstract] |
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S01.00045: Improvements on direct-bonded copper, atom chips used for Cold-Atom Atomic Interferometry. Johnathan White, James Stickney, Rudy Kohn, Brian Kasch, Stacy Schramm, Spencer Olson, Matthew Squires The Air Force Research Laboratory (AFRL) has been developing atom chips for use with cold-atom sensing and atom interferometry. We detail numerous advances in processing and fabrication techniques. Design improvements support tighter traps and rapid prototyping. Development of vias allow atom chips to serve as vacuum-chamber walls, decreasing current demands. Fabrication innovations that improve planarization support the integration of micro-features on single chips and chip-based assemblies. [Preview Abstract] |
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S01.00046: Rotation Sensing with a Trapped Barium Ion Randy Putnam, Adam West, Wes Campbell, Paul Hamilton We present progress toward an experiment using a Zeeman qubit and a modified version of the recently developed spin-dependent kicks technique [1] to create an interferometric matter-wave gyroscope with a single $^{138}$Ba$^+$ ion in a linear Paul trap [2]. A rotation rate, $\Omega$ can be extracted by measuring the Sagnac phase: $\Phi=\frac{4\pi E}{hc^2}(N\vec{A})\cdot \vec{\Omega}$, where $E$ is the particle energy, and $N\vec{A}$ is the effective area of the interferometer. In order to reach sensitivities comparable to commercially available gyroscopes (\sim 1 $\mu$rad s$^{-1}$Hz$^{-1/2}$) we take advantage of the increased energy afforded by using massive particles and allowing the ion to orbit in the trap $N$ times before closing the interferometer. With the ion's long coherence time and a secular trap frequency of 10--100 kHz we hope to achieve $N=100$ orbits in the trap. We have trapped and shown coherent control of a Zeeman qubit using a mode-locked Nd:YAG laser. This includes observing both Rabi oscillations and Ramsey fringes using a Raman transition between the qubit states.\\ \\Reference:\\ \\ $[1]$ J. Mizrahi et al., Phys. Rev. Lett. 110, 203001 (2013)\newline $[2]$ W. C. Campbell and P. Hamilton, J. Phys. B. 50, 064002 (2017) [Preview Abstract] |
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S01.00047: Polyatomic Molecules for Precision Measurements Arian Jadbabaie, Nickolas Pilgram, Nicholas Hutzler Polar molecules are a robust platform for precision measurement searches of Charge-Parity (CP) violating physics beyond the Standard Model (BSM). When aligned in the lab frame, the molecules' large, internal electromagnetic fields serve as sensitive probes for symmetry violating electromagnetic moments of fundamental particles. Recent experiments have excluded BSM CP-violating leptonic physics at TeV energy scales. By performing measurements on laser-cooled and trapped molecules, this sensitivity could be extended by orders of magnitude. However, in diatomic molecules, electronic structures amenable to optical cycling cannot provide strong systematic error rejection via full polarization and internal co-magnetometer states. In contrast, certain polyatomic molecules exhibit both electronic structures favorable to laser-cooling and co-magnetometer states via nearly-degenerate mechanical modes, making them ideal candidates for advanced BSM searches. We report progress on two precision measurement experiments using isotopologues of YbOH: a beam measurement probing hadronic CP violation via the magnetic quadrupole moment of the 173Yb nucleus, and a measurement of laser-cooled and trapped 174YbOH to probe the electron EDM to search for new physics at the PeV scale. [Preview Abstract] |
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S01.00048: Precision Space-Based Atom Interferometry using NASA's Cold Atom Laboratory Jason Williams, David Aveline, Ethan Elliott, Vladimir Schkolnik, Nan Yu, Robert Thompson Precision atom interferometers (AI) in space are expected to become an enabling technology for future fundamental physics research, with proposals including unprecedented tests of the validity of the weak equivalence principle, measurements of the fine structure and gravitational constants, and detection of gravity waves and dark matter/dark energy. We will discuss our efforts at JPL to equip NASA's Cold Atom Lab facility (CAL), already operating as a multi-user facility onboard the International Space Station, to enable precision dual-species AI studies in space. The impact from this work will also be reviewed in the context of future space-based fundamental physics missions. [Preview Abstract] |
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S01.00049: Ultrahigh-Precision Measurement of the n = 2 Triplet P Fine Structure of Atomic Helium Using Frequency-Offset Separated Oscillatory Fields K. Kato, T. D. G. Skinner, E. A. Hessels The 2$^3$P$_1$-to-2$^3$P$_2$ fine structure interval in atomic helium is measured [1] to a precision of 25 Hz using the frequency-offset separated oscillatory fields (FOSOF) technique [2]. A beam of metastable helium atoms is produced in a liquid-nitrogen-cooled DC-discharge source, and is intensified using a two-dimensional magneto-optical trap. Atoms in the 2$^3$S state are optically pumped into m=+1 prior to entering the main experiment region. These atoms are excited to the 2$^3$P$_1$ (m=+1) state by a pulse of linearly polarized 1083-nm laser light. The 2$^3$P$_1$-to-2$^3$P$_2$ transition is driven by two time-separated microwave fields (at slightly offset frequencies). 447-nm and 1532-nm laser pulses excite atoms in the 2$^3$P$_2$ state up to the 18P Rydberg state, and the Rydberg atoms are Stark-ionized and counted. This background-free ion detection method is only sensitive to the atoms that experience a complete FOSOF sequence, eliminating the major systematic effects of previous experiments [3]. The excellent signal-to-noise ratio allowed for thorough investigation of systematic effects. [1] K Kato, TDG Skinner, EA Hessels PRL 121, 143002 (2018) [2] A Vutha, EA Hessels, PRA 92, 052505 (2015) [3] JS Borbely, et al, PRA 79, 060503 (2009) [Preview Abstract] |
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S01.00050: ULTRAFAST AND STRONG FIELD PHYSICS |
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S01.00051: Characterization of the plasmonic response of Au(111) surfaces by attosecond angular streaking. Marcelo Ambrosio, Uwe Thumm The attosecond streaking applies a short XUV pulse followed by a time-delayed IR pulse, to map information on the time-dependent electronic substrate response into a pulse-delay- and energy dependent photoelectron spectrum [1,2]. We calculated streaked photoemission spectra from Au(111) surfaces and investigated the substrate's response to the IR steaking pulse, employing the classical Fresnel's equations to evaluate the surface-reflected IR field [3]. We retrieve the induced plasmonic-phase and -amplitude enhancement from the streaked spectra and are able to distinguish between the plasmonic-IR phase shift and the electronic-transport time-delay contribution to the streaking phases. This indicates that streaking spectroscopy allows the characterization of the substrate dielectric response at the nm length scale. [1] J. Li et al., 2016, Phys. Rev. A 94, 051401(R). [2] E. Saydanzad et al., 2018, Phys. Rev. A 98, 063422. [3] M. J. Ambrosio et al., 2018, Phys. Rev. A 97, 043431. [Preview Abstract] |
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S01.00052: Ionization dynamics of metallo-endohedral fullerenes using hard x-rays from the SACLA Free Electron Laser Razib Obaid, Sven Augustin, Kirsten Schnorr, Nora Kling, Tsukasa Takanashi, Kuno Kooser, Thomas Wolf, Daehyun You, Kiyonobu Nagaya, Shin-ichi Wada, Eleanor Campbell, Li Fang, Claus-Peter Schulz, Thomas Pfeifer, Pascal Lablanquie, Hironobu Fukuzawa, Edwin Kukk, Kiyoshi Ueda, Nora Berrah We have investigated the ionization dynamics of a metallo-endohedral fullerene, Sc$_{\mathrm{3}}$N@C$_{\mathrm{80}}$, subsequent to core shell ionization using x-ray pump x-ray probe from the SACLA FEL. We site-selectively ionize the Sc (1s) with a fs hard x-ray pulse (pump) at 4.55 keV photon energy inducing core-ionization followed by an Auger cascade, to determine how electronic rearrangement affects nuclear motion leading to atomic rearrangement, bond elongation and breaking, fragmentation of the moiety and the cage, and bond (re)-forming. With a well-defined delayed second x-ray pulse (probe) at a photon energy of 5.0 keV, we monitored the transient structural changes by imaging the fragment ions. Results will be presented showing the effect of these two hard x-ray pulses on the fragmentation dynamics of the parent molecule. This work scientifically contributes in opening up new possibilities of studying gas phase ultrafast dynamics using hard x-ray pulses on large molecular targets, such as metallo-endohedral fullerenes. [Preview Abstract] |
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S01.00053: Analysis of multi-orbital contributions in HHG spectra through multiple single active electron simulations Ran Reiff, Tennesse Joyce, Agnieszka Jaron-Becker, Andreas Becker In multielectron atoms, full ab-initio simulation of high harmonic generation (HHG) spectra is not computationally feasible. The single active electron (SAE) approximation considers the dynamics of one electron in a frozen potential from the remaining electrons. Comparisons with multielectron methods (TDDFT, MCTDHF) have shown that SAE simulations (for an electron in the outer valence shell) often accurately reproduce HHG spectra up to the active electron's cut-off ($I_p+3.17U_p$) but fail to reproduce a second or extended plateau attributed to inner-shell electrons. We present inner-shell SAE potentials and simulations which, in conjunction with valence SAE results, display the expected plateau behavior without dynamic multielectron interactions. [Preview Abstract] |
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S01.00054: Substituent Effects on The Mechanisms and Dynamics of H$_{\mathrm{3}}^{\mathrm{+}}$ Formation from Organic Molecules In Strong Fields Marcos Dantus, Nagitha Ekanayake, Muath Nairat, Nicholas Weingartz, Benjamin Farris, Matthew Michie, Travis Severt, Balram Kaderiya, Peyman Feizollah, Bethany Jochim, Farzaneh Ziaee, Kurtis Borne, Pandiri Kanaka Raju, Kevin Carnes, Daniel Rolles, Artem Rudenko, James Jackson, Benjamin Levine, Itzik Ben-Itzhak Recent studies from our groups combining femtosecond time-resolved dynamics, photoion-photoion coincidence measurements, and theory have provided evidence for the existence of two reaction pathways for the formation of H$_{\mathrm{3}}^{\mathrm{+}}$ from methanol under strong-field ionization. Both reaction pathways are initiated by the ultrafast double ionization of the parent molecule and proceed through prompt formation of a roaming neutral H$_{\mathrm{2}}$ molecule. The roaming H$_{\mathrm{2}}$ fragment abstracts a third proton from the methyl carbon or from the hydroxyl oxygen leading to the formation of H$_{\mathrm{3}}^{\mathrm{+}}$. We have extended the study to a series of alcohols presenting an increased number of hydrogen atoms and thus H$_{\mathrm{3}}^{\mathrm{+}}$ formation pathways: methanol (CH$_{\mathrm{3}}$OH), ethanol (CH$_{\mathrm{3}}$CH$_{\mathrm{2}}$OH), 1-propanol (CH$_{\mathrm{3}}$CH$_{\mathrm{2}}$CH$_{\mathrm{2}}$OH), 2-propanol (CH$_{\mathrm{3}}$CH(OH)CH$_{\mathrm{3}})$, and tert-butanol ((CH$_{\mathrm{3}})_{\mathrm{3}}$COH). Similarly, we have studied the substitution of oxygen with sulfur, comparing ethanol and ethanethiol. We will discuss the new pathways found and their relative yields. [Preview Abstract] |
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S01.00055: Exploration of laser-driven electron-multirescattering dynamics in high-order harmonic generation. Peng-Cheng Li, Shih-I Chu We investigate the dynamical origin of multiple rescattering processes in high-order harmonic generation (HHG) associated with the odd and even number of returning times of the electron to the parent ion. We perform fully ab initio quantum calculations and extend the empirical mode decomposition method to extract the individual multiple scattering contributions in HHG. We find that the tunneling ionization regime is responsible for the odd number times of rescattering and the corresponding short trajectories are dominant. On the other hand, the multiphoton ionization regime is responsible for the even number times of rescattering and the corresponding long trajectories are dominant. Moreover, we discover that the multiphoton- and tunneling-ionization regimes in multiple rescattering processes occur alternatively. Our results uncover the dynamical origin of multiple rescattering processes in HHG for the first time. It also provides new insight regarding the control of the multiple rescattering processes for the optimal generation of ultrabroad band supercontinuum spectra and the production of single ultrashort attosecond laser pulse. This work was partially supported by DOE. P.C. Li was partially supported by NSFC (Grands No.11674268). [Preview Abstract] |
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S01.00056: Unambiguous identification of quantum pathways in multiphoton dynamics Norio Takemoto, B.D. Esry Understanding the dynamics of an atom or molecule exposed to ultrashort, intense laser pulses has long been a challenge. Even when the wave function---which, in principle, contains all such information---is available from a calculation, extracting the dynamical pathways can be very difficult. Moreover, there is no general prescription for doing so, requiring a new effort for each new problem. Even then, it is usually difficult to provide more than a qualitative definition. To try to address this situation, we will present a method to analyze both wave functions and observables that unambiguously---and quantitatively---defines quantum pathways labeled by both the total photon number and the net photon number. Our method is completely general in the sense that atoms and molecules of any complexity can be treated. We will examine the extent to which knowing the total and net photon numbers that interfere to produce a specific feature and how they do so enhances our understanding of the dynamics. [Preview Abstract] |
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S01.00057: Photoionization cross section and time-delay of atoms confined in C$_{\mathrm{240}}$ versus C$_{\mathrm{60}}$. Maia Magrakvelidze, Himadri Chakraborty We investigate the effects of confinement and electron correlation on the photoemissions of noble gas atoms sequestered endohedrally in C$_{\mathrm{240}}$ and compared with the corresponding results of C$_{\mathrm{60}}$ confinement. The time-dependent local density approximation (TDLDA) method [1] with Leeuwen and Baerends (LB94) exchange-correlation functional is employed in the calculation. The core of 240 C$^{\mathrm{4+}}$ ions is jelliumized to ignore the carbon $K$-shell structures. We compute subshell cross sections and angle-integrated Wigner-Smith (WS) time-delays [2] for atomic-type as well as atom-fullerene hybrid-type levels. We examine the size effects of the molecular cage on the plasmonically enhanced [3] strength of the atomic ionization. Furthermore, the behavior of photoemission WS time delays in attoseconds, induced by this enhancement as well as by the confinement-modified atomic Cooper minima [4], as a function of fullerene size and electronic structure, is scrutinized in detailed. [1] Choi \textit{et al.,} PRA \textbf{95}, 023404 (2017) [2] Dixit \textit{et al}., PRL \textbf{111}, 203003 (2013) [3] Madjet \textit{et al.}, PRL \textbf{99}, 243003 (2007) [4] Magrakvelidze \textit{et al}., PRA\textbf{ 91}, 053407 (2015). [Preview Abstract] |
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S01.00058: Initial state and polarization dependence of multi-photon ionization of Li Nishshanka DeSilva, Bishnu Acharya, Kevin Romans, Thusitha Arthanayaka, Katrina Compton, Kyle Foster, Sachin Sharma, Daniel Fischer After the development of femto-second intense laser sources, numerous studies of multi-photon or tunnel ionization revealed details of the atomic processes and opened routes to control their dynamics. As far as atoms are concerned, earlier experiments were mostly limited to noble gases because they are easily prepared at low temperatures for ionization studies. Here, we report on experiments performed with lithium. In contrast to noble gases, Li has only a single valence electron whose state can optically be excited before the ionization by the intense laser pulse. We prepare our Li target in an all optical trap (AOT) by laser cooling achieving milli-Kelvin temperatures. The atoms can be excited to a p-state with full control of the magnetic sublevel, i.e. the orientation of the angular momentum vector. After the ionization with 7 fs pulses of an OPCPA with intensities exceeding 10$^{\mathrm{12}}$W/cm$^{\mathrm{2}}$, the momentum vector of the electron is measured in a Reaction Microscope. This enables to address fundamental questions on the initial state dependence of multi-photon ionization. In particular, the influence of relative polarizations of target and laser pulse is studied and the most fundamental conceivable helical systems and their short-time dynamics in intense strong fields is investigated. [Preview Abstract] |
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S01.00059: Wigner Time Delay for Xe 5s photoemission in the Second Cooper Minimum Region using RMCTD Aarthi Ganesan, Pranawa Deshmukh, Steven Manson We have examined the Wigner time delay of Xe 5s photoelectrons in the region of second Cooper minimum using the RRPA [1-3], the RRPA-R [4] and the RMCTD [5] methodologies. Atomic time delay is Wigner-Eisenbud-Smith (WES) [6-9] plus Coulomb laser coupling components. The WES component [9] is studied. Electron correlations and relativity[2-3] influence WES time delay strongly near Cooper minima, resonances, etc. Xe 5s time delay near the first Cooper minimum was studied earlier [2-3], but a second Cooper minimum exists at \textasciitilde 150 eV [10]. The Xe 5s photoelectron angular distribution, using the RMCTD methodology agrees bettert with experiment [11] compared with RRPA or RRPA-R results. Since the angular distribution depends on the phases of matrix elements, this suggests that RMCTD should accurate for WES time delay, which depends on the derivatives of these same phases. The results for the various theoretical models are compared. Work partially supported by SERB (India) and the US DOE. [1] W. R. Johnson and C. D. Lin, Phys. Rev. A \textbf{20}, 964 (1979); [2] A. S. Kheifets, Phys. Rev. A \textbf{87}, 063404 (2013); [3] S. Saha \textit{et al.,} Phys. Rev. A \textbf{90}, 053406 (2014); [4] V. Radojevic, M. Kutzner and H. P. Kelly, Phys. Rev. A \textbf{40 }727 (1989); [5] V.Radojevic and W. R Johnson, Phys. Rev. A \textbf{31, }2991 (1985); [6] E. P. Wigner, Phys. Rev. \textbf{98}, 145 (1955) [7] L. Eisenbud, Ph.D. thesis, Princeton University, 1948; [8] F. T. Smith, Phys. Rev. \textbf{98}, 145 (1955); [9] A. S. Kheifets \textit{et al.,} Phys. Rev. A \textbf{94}, 013423 (2016); [10] S. B. Whitfield \textit{et al., }J Phys. B\textbf{ }\textbf{40}, 3647 (2007); [11] G. Aarthi \textit{et. al.,} 7$^{\mathrm{th}}$ ISAMP TC7, Jan. 2018, Tirupati. [Preview Abstract] |
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S01.00060: Control of Ion Polarization in the Pump-Probe Ionization of Helium Saad Mehmood, Eva Lindroth, Luca Argenti Attosecond pump-probe ionization processes can be used to prepare atomic ions in a coherent superposition of states with opposite parity. The multiphoton shake-up ionization of Helium, in particular, generates ions with a same principal quantum number and a net dipole moment that evolves on a time scale of several picoseconds, due to spin-orbit coupling. In this work we use an ab initio time-dependent close-coupling code [1,2] to study how the coherence between the 3s, 3p, and 3d levels of the Helium ion can be controlled from the parameters of the ionizing-pulse sequence. The observed periodic revival, on a picosecond time scale, of the ion dipole moment gives access to the study of the ionization of oriented targets. [1] L Argenti and E Lindroth, Phys. Rev. Lett. 105, 053002 (2010). [2] T Carette et al., Phys. Rev. A 87, 023420 (2013). [Preview Abstract] |
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S01.00061: Resonant attosecond transient absorption and photoelectron spectra of argon Coleman Cariker, Eva Lindroth, Luca Argenti Technological advances with ultrafast lasers make it possible to probe the dynamics of metastable electronic wavepackets in atoms and molecules with a temporal resolution shorter than the excited states' lifetime. Here, we use an ab initio time-dependent close-coupling method [1] to simulate the electron dynamics in an argon atom excited by weak extreme ultraviolet pump pulses and dressed by weak to moderately strong infrared pulses. We study how electron dynamics manifests itself in the transient absorption and photoelectron spectrum of the atom as a function of the parameters of the pump-probe pulse sequence. From the ab initio calculations, we also extract the radiative couplings between the essential states of the atom, which we use in a finite-pulse multiphoton extension of Fano's formalism [2][3] to simulate the pump-probe spectra analytically. Such model calculations allow us to study how to control the population, phase and lifetime of argon's bright autoionizing states via their radiative coupling to other metastable states, or to the continuum, at a considerably smaller computational cost than with full-fledged ab initio simulations. [1] L Argenti et al, PRA 105, 053002 (2010). [2] A. Jiminez-Galan et al, PRA 93, 023429 (2016). [3] U. Fano, Phys Rev 124, 1866 (1961). [Preview Abstract] |
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S01.00062: Mollow sidebands in macroscopic high-harmonic generation Tennesse Joyce, Agnieszka Jaron-Becker In the high-harmonic spectra of many molecular ions, it was recently predicted that the usual odd harmonics can be accompanied by sidebands at non-integer multiples of the fundamental frequency, analogous to the appearance of Mollow triplets in quantum optics. These sidebands result from competition between two nonperturbative processes, Rabi oscillation and high-harmonic generation, and therefore offer additional insight into the dynamics of the molecule in a strong laser field. However, it is not immediately clear whether the effect is robust enough to appear in a real experiment. To answer this question, we estimate the macroscopic harmonic spectrum by combining many single-molecule calculations at different intensities, obtained with either time-dependent density functional theory or a 1D model potential. Our results suggest that not only do the Mollow sidebands remain around the same order of magnitude as the main harmonics in intensity, but they are also radiated at wider angles, and can therefore be distinguished from the main harmonics, and in principle also isolated as an alternative radiation source. [Preview Abstract] |
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S01.00063: Probing molecular dynamics by Time-resolved Ionization Spectroscopy Yusong Liu, Spencer Horton, Chuan Cheng, Samuel McClung, Thomas Weinacht Ionization can serve as a universal probe of excited state molecular dynamics, such as internal conversion, dissociation, and isomerization. We conduct UV pump VUV probe spectroscopy measurements measuring both ions and electrons with Velocity Map Imaging (VMI) resolution. We have developed a delay-stamped configuration of pump-probe experiments based on a time stamping camera (Timepix3). The camera allows to measure the 3D vector momentum of all species of ions produced by photoionization without gating the detector or performing an inverse Abel transform. Furthermore, by switching the voltages on the VMI plates, we collect both electrons and ions for each delay. [Preview Abstract] |
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S01.00064: Molecular Ionization of Chloromethane in Strong Fields: Nearest Neighbor Gateway to Highly Charged Ions Barry Walker, Pat Grugan, Nagitha Ekanayake, Sam White, Siyu Luo, Panpan Ruan The strong and ultrastrong field-molecule interaction is a complex, many-body process involving multiple ionization processes that evolve during an ultrafast laser pulse. We present ion yields and molecular fragment energies for the ionization of chloromethane (CH$_{3}$Cl) in a laser field with intensities spanning from 10$^{14}$ W/cm$^{2}$ to 10$^{17}$ W/cm$^{2}$. As the laser intensity increases, ionization of CH$_{3}$Cl is observed to pass from molecular tunnelling, to enhanced ionization, to an atomic-like response. The energy spectra of the ions show no dependence on the intensity and have their source in dissociative molecular ionization. A classical model of an aligned C-Cl ion is used to dynamically model the interaction. Following an initial molecular ionization process, our results show enhanced ionization is a driving influence in the formation of low charge states until ionization become atomic-like and involves tightly bound ion states whose ionization is unaffected by nearest neighbor ions of similar ion charge. [Preview Abstract] |
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S01.00065: Strong-field control of H$_3^+$ formation pathways in methanol: Local versus extended H$_2$ roaming Naoki Iwamoto, Charles J. Schwartz, J.L. Napierala, S.N. Tegegn, A. Solomon, S. Zhao, E. Wells, Bethany Jochim, Kanaka Raju P., T. Severt, Peyman Feizollah, H. Lam, Tomthin Nganba Wangjam, V. Kumarappan, K.D. Carnes, I. Ben-Itzhak Using the CD$_3$OH isotopologue of methanol, the ratio of D$_2$H$^+$ to D$_3^+$ formation is manipulated by changing the characteristics of the intense laser pulse. Formation of D$_2$H$^+$ indicates a process involving two hydrogen atoms from the methyl side of the target and a proton from the hydroxyl side, while detection of D$_3^+$ indicates direct formation involving only the methyl group. An adaptive control strategy that employs image-based feedback to guide the learning algorithm results in an enhancement of the D$_2$H$^+$/D$_3^+$ ratio by a factor of approximately two. The optimized pulses have time structures on the order of 100 fs. Systematic changes to the linear chirp and higher order dispersion terms of the laser pulse are compared to the results obtained with the optimized pulse shapes. [Preview Abstract] |
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S01.00066: Time-Resolved Photoion Spectroscopy of a UV-Induced Ring-Opening and Dissociation Reaction Shashank Pathak, Jan Tross, Daniel Rolles, Mike Ashfold, Christopher Hansen, Rebecca Ingle, Rebecca Boll, Carlo Callegari, Michele Di Fraia, Oksana Plekan, Kevin Prince, Benjamin Erk, Raimund Feifel, Richard Squibb, Ruaridh Forbes, David Holland, Robert Mason, Arnaud Rouzee We report the results of an experiment studying the UV-induced ring-opening and subsequent unimolecular dissociation of a heterocyclic ring molecule using time-resolved photoion and photoelectron spectroscopy at a seeded free-electron laser. Photoions and photoelectrons were recorded simultaneously using a covariance magnetic bottle spectrometer. The photoelectrons primarily monitor the ultrafast electronic excitation and de-excitation pathways, while the time-resolved fragment ion yields trace subsequent dissociation dynamics of the excited reaction products. [Preview Abstract] |
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S01.00067: Time-resolved imaging of isolated molecular dynamics with a MHz repetition-rate relativistic electron probe Brandon Griffin, Daniel Slaughter, Daniele Filippetto, Fu-Hao Ji, Xiaojun Wang, Martin Centurion, Joshua Williams Developments in the time-resolved imaging capabilities of isolated molecules at the Advanced Photo-injector Experiment facility at LBNL have been made. We report on progress in ultrafast, 750 keV, electron diffraction measurements from gas-phase molecules (GUED) with sub-{\AA} spatial and 200 fs temporal resolution. Headway towards first direct-observations of photo-driven molecular dynamics via impulsive alignment using the High Repetition-rate Electron Scattering beamline will be discussed. Upgrades to the GUED apparatus will be presented accompanied by recent experimental results. [Preview Abstract] |
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S01.00068: Micro-Focused MHz Pink Beam for Time-Resolved X-Ray Emission Spectroscopy Ming-Feng Tu, Gilles Doumy, Andre Al Haddad, Anne Marie March, Stephen Southworth, Yoshiaki Kumagai, Donald Walko, Linda Young, Christoph Bostedt X-ray emission spectra (XES) in the valence-to-core (vtc) region offer direct information on occupied valence orbitals. They emerge as a powerful tool for the ligand identification, bond length, and structural characterization. However, the vtc feature is typically two orders of magnitude weaker than K$\alpha$ emission lines, making it hard to collect, especially for transient species. To overcome the difficulty, pink beam excitation capability was demonstrated recently at Sector 7 of the Advanced Photon Source. A water-cooled at mirror rejects higher harmonics, and beryllium compound refractive lenses (CRLs) focus the reflected fundamental beam (pink beam) to a 40$\mu m$ x 12$\mu m$ elliptical spot at sample target that matches the laser spot size used for photoexcitation. With an X-ray flux of $10^{15}$ photons per second, non-resonant XES spectra were taken on iron(II) hexacyanide and on photoexcited iron(II) tris(2, 2’-bipyridine). We could reproduce previous measurements with only a fraction of the acquisition time, demonstrating the ability to measure high quality spectra of low concentration species. [Preview Abstract] |
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S01.00069: Multi-channel contributions to High Harmonic Generation (HHG) in solids. Francisco Navarrete, Marcelo Ciappina, Uwe Thumm While HHG from gaseous atoms is well understood [1], HHG from solids is discussed theoretically for decades [2] and still debated [3-5], but scrutinized experimentally only recently [3]. We investigated intra- and inter-band contributions to HHG in ZnO and MgO model solids within a single-active-electron approximation and an adiabatic basis-set approach. We compare HHG spectra after integration over initial states from entire BZ with contributions from the band center ($\Gamma $ point) alone over a range of IR-driver-pulse field strengths. In addition, we use our numerical spectra and intensity-dependent cut-off frequencies for ZnO and MgO crystals to benchmark analytical approximations. [1] Le \textit{et al.}, Phys. Rev. A \textbf{80}, 013401 (2009). [2] Plaja and L. Roso-Franco, \textit{Phys. Rev. B} \textbf{45}, 8334 (1992). [3] Ghimire \textit{et al}., Nat\textit{. Phys,} \textbf{7}, 138 (2011). [4] Wu \textit{et al.,} Phys. Rev. A \textbf{91}, 043839 (2015). [5] Vampa \textit{et al}., \textit{Phys. Rev. Lett,} \textbf{113}, 073901 (2014). [Preview Abstract] |
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S01.00070: QUANTUM INFORMATION AND QUANTUM OPTICS |
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S01.00071: Optical Demonstration of the Zeno Effect Julia Spina, Courtney Krafczyk, Paul Kwiat The quantum Zeno effect occurs when repeated projective measurements are applied to an otherwise evolving quantum state, thereby freezing the state in its current configuration. We investigate an optical implementation of the Zeno effect. Specifically, we induce state evolution by applying perturbative displacements to the transverse spatial mode of a Gaussian light beam. By administering frequent projective measurements to the evolving state using a single mode fiber, we demonstrate that the evolution of the spatial mode from its initial state is, indeed, inhibited. While implementing this experiment with a laser admits a classical explanation, incorporating a true single photon source would demonstrate the quantum nature of the effect. [Preview Abstract] |
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S01.00072: Spectral Hole Burning on an Optical Magnetic Dipole Transition Zachary Buckholtz, Nicholas Brewer, Eli Mueller, Deniz Yavuz Rare-earth doped crystals have gained quite a bit of interest over the last few decades due to their unusual properties. They have very long coherence times for a solid giving them interesting applications in quantum information and quantum memory. Their rich electronic structure contains optical frequency magnetic dipole transitions giving them applications in building metamaterials. Many of the applications of rare-earth doped crystals require precise control of which rare-earth transitions are being addressed. Due to the complex nature of solids, this task can be quite involved, but can be accomplished through a process called spectral hole burning (SHB). We present our results of SHB on an optical magnetic dipole transition in europium doped yttrium orthosilicate (YSO). We also present our progress towards observing EIT on the selected magnetic transition. [Preview Abstract] |
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S01.00073: Optical Angular Momentum manipulations in a Four Wave Mixing process Nikunjkumar Prajapati, Nathan Super, Nicholas Lanning, Jon Dowling, Irina Novikova We investigate the spatial and quantum intensity correlations between the probe and Stokes optical fields produced via four-wave mixing in a double-$\lambda $ configuration. When both fields carry non-zero optical orbital angular momentum (OAM), we observed that the topological charge of the generated Stokes field obeyed the angular momentum conservation law and that the intensity squeezing between the two fields were mostly independent on their OAM value. We also investigated the case of a composite-vortex pump field, containing two closely-positioned optical vortices, and showed that the generated Stokes field carried the OAM corresponding to the total topological charge of the pump field. Our current work focuses on showing squeezing and polarization entanglement using a dual-rail experimental arrangement, for which we are developing a simplified version of a truncated SU (1,1) interferometer. [Preview Abstract] |
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S01.00074: Towards an Experimental Demonstration of Superadditivity through the Dephrasure Channel Spencer Johnson, Nicholas Laracuente, Marius Junge, Eric Chitambar, Paul Kwiat One of the key difficulties in computing channel capacities for quantum communication channels is the superadditivity of coherent information. In stark contrast to classical communication, quantum channels can in principle exhibit ``superadditivity'': the coherent information capacity of multiple uses can exceed - albeit only slightly - the sum of the individual channel's capacities. Superadditivity of coherent information has been established theoretically in the case of the dephrasure channel, which combines erasure and dephasing. The dephrasure channel exhibits superadditivity for as few as two channel uses; this, combined with the channel's simple form, makes it a good candidate for experimental investigation. We report on ongoing progress to construct the dephrasure channel as a testbed for nonadditivity in quantum channels. [Preview Abstract] |
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S01.00075: Saturation and alternate pathways in four-wave mixing in rubidium Erik Brekke, Noah Swan We have examined the frequency spectrum of the blue light generated via four-wave mixing in a rubidium vapor cell inside a ring cavity. At high atomic density and input laser power, two distinct frequency components separated by 116 MHz are observed, indicating alternate four-wave mixing channels through the 6p$_{\mathrm{3/2\thinspace }}$hyperfine states. The dependence of the generated light on excitation intensity and atomic density are explored, and indicate the primary process has saturated. This saturation results when the excitation rate through the 6p state becomes equal to the rate through the 5p state, giving no further gain with atomic density while a quadratic intensity dependence remains. The four-wave mixing process remains a promising source of 420 nm light with careful selection of the excitation parameters. [Preview Abstract] |
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S01.00076: Development of highly nondegenerate polarization entanglement on a waveguide SPDC source Kristina Meier, Fumihiro Kaneda, Paul Kwiat As benchtop quantum information protocols become increasingly more advanced and the distances over which these experiments are performed become significantly longer, integrated optics provides a small, robust, and practical alternative to traditional bulk optics. Specifically, waveguide technology makes it possible to create bright single-photon sources for use on platforms where weight and stability requirements are limiting factors. For our goals, we are working on the characterization of a highly nondegenerate Spontaneous Parametric Down-Conversion waveguide source of polarization-entangled pairs on a PPKTP crystal. Our source uses type-II phase-matching to create collinear signal and idler photons at 1550 nm and 810 nm, respectively. Our past waveguide iterations have produced polarization-entangled pairs with a concurrence of 0.63 and a state purity of 0.72. To improve these numbers, we are experimenting with interleaved periodic poling, in contrast to consecutive poling, to reduce the amount of post-compensation required to achieve high polarization entanglement, as well as various mode filtering methods to reduce instabilities arising from the multiple pump spatial modes supported by the waveguide source. [Preview Abstract] |
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S01.00077: Quantum State Transportation of Rubidium Atoms inside a Photonic Waveguide Mingjie Xin, Zilong Chen, Wui-Seng Leong, Shau-Yu Lan Coherent interactions between electromagnetic and matter waves lie at the heart of quantum science and technology. We optically trap cold 85Rb atoms in a hollow-core photonic crystal fiber and use the waveguide elds as matter-wave beam splitter and mirror pulses to demonstrate a Mach-Zehnder interferometer. The results suggest that the coherence of a quantum superposition state of atoms can be coherently interrogated by the optical guided mode inside the hollow core fiber. We also experimentally study the ground state coherence properties of 85Rb atoms inside the hollow core fiber. We find that, the dephasing of atomic ground states is mainly due to the inhomogeneous broadening of differential ac stark shift between the ground states introduced by the optical dipole beams. We introduce vector light shift to cancel the differential ac stark shift. After the cancellation, we achive a long coherence time of T=250 ms, and able to maintain the coherence of a quantum superposition state over one centimeter distance of transportation along the optical fiber. The integration of phase coherent photonic and quantum systems here shows great promise to the advance capability of atom interferometers, compact atomic clock, quantum memory and optical fiber quantum network. [Preview Abstract] |
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S01.00078: Recent progress on using ultrafast electron microscopy to study fundamental electron-photon interactions Jared Zeman, Ryan Anthony-Ceres, Brett Barwick We report progress on using low energy ultrafast electron microscopy to demonstrate the exchange of quantized amounts of orbital angular momentum (OAM) between electrons and photons. The goal of our project is to demonstrate a new method whereby arbitrary amounts of OAM can be transferred to free electrons using the Kapitza-Dirac effect. This technique would enhance the sensitivity of ultrafast electron microscopes, electron interferometers and provide a new method of shaping the spatial properties of electron beams. In addition, we will discuss our progress on using all-optical techniques to compress free electron pulses from 100's of femtoseconds to tens of femtoseconds or shorter. If these efforts are successful the temporal resolution of ultrafast electron microscopes would be improved by more than an order of magnitude, allowing dynamics of systems that have motions too fast for current technologies. [Preview Abstract] |
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S01.00079: Quadrupole Raman transitions in ultracold $^{87}$Rb driven by optical vortex beams Joseph D. Murphree, Maitreyi Jayaseelan, Zekai Chen, Elisha Haber, Nicholas P. Bigelow Two-photon Raman processes are widely used to coherently manipulate atoms using a pair of laser fields. For dipole transitions, the transfer of angular momentum to the cloud is partitioned into one exchange between the field’s polarization and the electron’s angular momentum and another exchange between the field’s orbital angular momentum (OAM) and the center-of-mass motion of the atom. Quadrupole transitions lift these restrictions, allowing for a richer interplay between polarization, OAM, and the angular momenta of the atom. This opens up the possibility of electronic state control using both the polarization and spatial mode of the applied fields and modified mechanical effects. These transitions are amplified to experimentally relevant magnitudes in the presence of large electric field gradients. This enhancement has been observed in atoms in the evanescent fields generated by light passing through prisms and in trapped ions illuminated by singular beams propagating in free space. We consider an ultracold cloud of Rb-87 atoms undergoing two-photon Raman interactions on the 5S$\rightarrow$4D quadrupole transition. By using combinations of Gaussian and Laguerre--Gaussian beams, we explore the effects of the fields’ polarizations and orbital angular momenta on the atoms. [Preview Abstract] |
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S01.00080: Abstract Withdrawn
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S01.00081: Testing the limit of infinite-range interactions mediated by optical nanofibers Hyun Gyung Lee, Hyok Sang Han, Kanupriya Sinha, F.K. Fatemi, S.L. Rolston Electromagnetic fields confined to waveguides enables effectively infinite-range interactions between macroscopically separated quantum objects. An optical nanofiber(ONF) is an excellent platform to study long-distance quantum interactions between atoms near the fiber. In previous work, an ONF mediated super- and sub-radiance between atoms that were separated by a fraction of 1 mm[1]. Still, the practical limit of infinite-range interactions remains to be tested and interesting crossover is expected around the range corresponding to the atom's optical decay lifetime, where non-Markovian effects become important. In this work, we use a pair of ONFs placed in the same cloud of magneto-optically trapped atoms that are connected via conventional single-mode fiber outside the vacuum chamber. The benefit of this configuration is two-fold: (i) We can vary the interaction range between the two ONF systems by choosing different lengths of the connecting fiber outside the chamber; (ii) The spatial proximity between the two ONFs minimizes the differential perturbation due to the inhomogeneity of both driving and ambient field. We will present details of the experimental implementation as well as current progress. [1] Solano, P. et al, Nat. Commun. 8, 1857 (2017). [Preview Abstract] |
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S01.00082: Dual continuous cold atom beam accelerometer/gyroscope. Michael Manicchia, Jeff Lee, George Welch, Frank Narducci We report on studies completed while constructing a continuous dual atom beam accelerometer/ gyroscope. Two opposing beam atom interferometers can distinguish between linear and rotational motion. Our design uses cold and slow moving atoms that originate from a 2D magneto-optical trap (MOT). The transit time of these atoms through continuous Raman laser fields acts as the `pulse' of light for the interferometer atom optics. We use a lock-in detection method for improved signal-to-noise ratio. We also explore the effects of different hyperfine transitions within the $^{\mathrm{85}}$Rb D2 line for optical pumping effectiveness. We find that the optical pumping beam can also be used as a shutter on the atomic beam. We present the status of the construction of our prototype. We present measurements of narrow velocity profiles from our source and compare the results to a time-of-flight measurement performed on the source when it is pulsed. Finally, we demonstrate Raman spectroscopy and Ramsey interference in the system. This work was funded by the Office of the Secretary of Defense. [Preview Abstract] |
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S01.00083: Table Top Ultrasensitive Gravitational Wave Detector Using Superluminal Ring Lasers Selim Shahriar, Minchuan Zhou, Zifan Zhou, Jacob Scheuer We propose a new scheme of a gravitational wave (GW) detector, composed of a pair of orthogonally oriented superluminal ring lasers (SRLs). Each laser contains a gain medium that is tailored to provide a negative dispersion for producing the superluminal effect in order to enhance the sensitivity of the detector. We evaluate the quantum noise limited sensitivity of the detector, considering shot noise and radiation pressure noise. A gravitational wave modulates the length of the two laser cavities, out of phase with respect to each other, and creates a frequency modulation in the beat signal. In the limit where the response time of the laser cavity to a change in the cavity length is shorter than the period of the GW signal, the beat frequency tracks the evolution of the GW. Using a 10 meter long cavity for each SRL with effective group index of 10$^{\mathrm{-4}}$, and intra-cavity power of 1 kilo-watt, we can achieve a quantum noise limited sensitivity a factor of ten better than the current Advanced LIGO with 4km long arms over the same band: from 50 Hz to 500 Hz. If a 1 meter long cavity is used for each SRL, the optimal sensitivity is nearly a factor of 100 better than that of Advanced LIGO, but for a band from 500 Hz to 10 kHz. [Preview Abstract] |
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S01.00084: Potential roughness suppression in microwave chip traps Shuangli Du, Andrew Rotunno, Kameron Sullivan, Seth Aubin We present the results of a theoretical study comparing trapping potential roughness of DC micromagnetic chip traps and microwave chip traps. The AC Zeeman potential produced by a microwave near-field can be used for spin-specific trapping of ultracold atoms and are an alternative to DC magnetic forces. Notably, magnetic chip traps suffer from potential roughness due to the imperfections in chip wires, which has limited their application in physics experiments, including atom interferometry. Our numerical study finds that AC Zeeman potential can be expected to significantly suppress this roughness with respect to their DC counterpart. In a first approach, we simplify the trace to a thin wire with small current distortions and then compare the AC and DC Zeeman potentials produced by the same magnetic near-field. In a second approach, we investigate the AC skin effect by simulating the near-field of a microstrip transmission line with a localized conductivity defect. In both approaches, we find that the microwave trap suppresses the roughness from wire imperfections significantly. [Preview Abstract] |
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S01.00085: Large time-bandwidth photonic waveguide coupled light storage Wui Seng Leong, Mingjie Xin, Zilong Chen, Shau-Yu Lan Integrating light storage or optical delay line in an optical fibre is an attractive component in connecting long distance optical communication networks. Although silica-core optical fibres are excellent in transmitting broadband optical signals, it is challenging to tailor its dispersive property for long light storage time. Coupling tunable dispersive medium with an optical fibre is promising in supporting high performance optical delay line memory while transmitting the light with small loss. Here, we load cold Rb atomic vapour in an optical trap inside a hollow-core fibre and demonstrate light storage using electromagnetically-induced-transparency (EIT). We achieve over 20 ms of the storage time with 1 MHz bandwidth of the pulse. The storage time-bandwidth product exceeds $10^4$. Our long memory built-in optical fibre could be used for buffering and regulating classical and quantum information flow between remote networks. [Preview Abstract] |
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S01.00086: A fully-integrated single-photon source based on single Rb atoms Garrett Hickman, Cecilia Vollbrecht, Brandon Mehlenbacher, Zhaoning Yu, Yuzhe Xiao, Randall Goldsmith, Mikhail Kats, Mark Saffman We describe recent work towards a fully-integrated single-photon source based on the use of single atoms captured from a grating magneto-optical trap (GMOT). Single Rb atoms from a fiber-coupled GMOT will be loaded into an optical dipole trap formed by light from an integrated polarization-maintaining (PM) fiber. Trapped single atoms will be excited to the $^{2}P_{1/2}$ state using resonant light. The resulting single-photon florescence will be collected through the same PM fiber as is used for trapping, and routed to further experiments. We describe progress towards an intermediate implementation incorporating integrated optical fibers and free space light sources. The completed, fully-integrated single-photon source will have numerous applications in quantum communications and quantum information processing, and particularly in improvement of the performance of quantum key distribution systems. [Preview Abstract] |
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S01.00087: $^{138}$Ba$^+$ and $^{171}$Yb$^+$ Dual Species Modular Quantum Network Allison Carter, Martin Lichtman, Ksenia Sosnova, Clayton Crocker, Sophia Scarano, Christopher Monroe Trapped ions are a leading platform for quantum computing, with long coherence times and high fidelity operations. To address the challenge of scaling such systems, we utilize a modular architecture consisting of separate traps with photonic links for remote entanglement. In our experiment, each of two traps contain a $^{171}\textrm{Yb}^+$ memory qubit and a $^{138}\textrm{Ba}^+$ communication qubit. We report progress in the development of this system, including improvements in light collection, higher purity of the single photons generated for remote entanglement, increased fidelity in our ion-photon entanglement, and the construction of the second module. The outlook toward a three trap system and entanglement protocols for that system are discussed. [Preview Abstract] |
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S01.00088: Nonlinear quantum optics assisted by atomic motion Wanxia Cao, Xingda Lu, Yanhong Xiao, Heng Shen We present an atomic system where quantum nonlinear optics can be realized using linear atom-light interactions, but with effective feedback provided by moving atoms. Two spatially-separated optical fields (channels) can display quantum correlations with each other, with each channel undergoing the normal Electromagnetically Induced Transparency. We present a theoretical model to describe such a system. Atomic dynamics in three different regions of a vapor cell are considered, two within each laser beams and one outside the laser beams, and the coupling between regions, including the Langevin noises, are taken into account. We achieved excellent agreement between the experiment and the theory. Our system demonstrates the possibility of low power nonlinear quantum optics without the need of traditional nonlinear atom-light interaction configuration. [Preview Abstract] |
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S01.00089: Detecting the Macroscopic Quantumness in Atomic Systems Chang-Hau Kuo, Yao-Chun Yu, Guang-Yin Chen, Yueh-Nan Chen, Che-Ming Li, Jung-Jung Su, Chih-Sung Chuu Atomic ensemble interacting with nonclassical light provides an interesting platform for exploring the quantum nature of macroscopic systems. In this paper we study the quantum dynamics of the timed Dicke state in a two-level atomic ensemble induced by the absorption of a single photon. Using the extended Leggett-Garg inequality and quantum coherence witness, we explore the possibilities to identify the macroscopic quantumness in the timed Dicke state with a large number of atoms. As another example, we study the quantum dynamics of three-level atomic system, a popular candidate for storing quantum states in atoms. Our work shows that the extended Leggett-Garg inequality and quantum coherence witness may be exploited to probe the quantumness preserved in atomic quantum memory. [Preview Abstract] |
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S01.00090: Narrow-line cooling and imaging of Ytterbium atoms in an optical tweezer array Samuel Saskin, Jack Wilson, Brandon Grinkemeyer, Jeff Thompson Engineering controllable, strongly interacting many-body quantum systems is at the frontier of quantum simulation and quantum information processing. Arrays of laser-cooled neutral atoms in optical tweezers have emerged as a promising platform, because of their flexibility and the potential for strong interactions via Rydberg states. Existing neutral atom array experiments utilize alkali atoms, but alkaline-earth atoms offer many advantages in terms of coherence and control. We present a technique to trap individual alkaline-earth-like Ytterbium (Yb) atoms in optical tweezer arrays. The narrow $^1$S$_0\,$ - $^3$P$_1\,$ intercombination line is used for both cooling and imaging in a magic-wavelength optical tweezer at 532 nm. The low Doppler temperature allows for imaging near the saturation intensity, resulting in a very high atom detection fidelity. This platform will enable advances in quantum information processing and quantum simulation. We also present work on spectroscopy of Yb Rydberg states, which is incomplete in the literature, and initial exploration of the properties of Yb Rydberg states in optical tweezers. We expect the strong hyperfine coupling in the Yb Rydberg states to possibly enable novel schemes for two-qubit gates and implementing spin Hamiltonians. [Preview Abstract] |
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S01.00091: Toward Rydberg entanglement and optical qubit control in strontium atom arrays Adam Shaw, Alexandre Cooper, Ivaylo Madjarov, Jacob Covey, Ryan White, Vladimir Schkolnik, Jason Williams, Manuel Endres We present recent results in high-fidelity and low-loss imaging of single strontium atoms in optical tweezers, as well as progress toward Rydberg-mediated entanglement in defect-free arrays. The strontium clock state is metastable and optically resolvable, allowing for its use as both a stage for single-photon Rydberg excitation and as a basis state in an optical qubit realized via coherent driving of the clock transition. We discuss progress toward both avenues, as well as the potential for optical qubits interacting via Rydberg dressing. [Preview Abstract] |
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S01.00092: Levitated optomechanics with a Mie particle A Kani, Tushar Biswas, Mishkat Bhattacharya Mie particles are gaining interest in levitated optomechanics as they offer stronger coupling to gravitational forces compared to Rayleigh particles, as well as opportunities for testing quantum mechanics at the macroscale. We present the dynamics of an optically trapped Mie particle in free space as well as in a hollow-core photonic crystal fiber. Light is confined within the trapped particle through coupling into a whispering gallery mode (WGM). We investigate the setup geometry and particle asphericity to maximize coupling into the WGM, radiation pressure, and control over particle dynamics. The proposed model has potential applications in optomechanical cooling, sensing and matter wave interferometry. [Preview Abstract] |
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S01.00093: Ultra-cold strontium atoms in a high finesse optical micro-cavity Lucas Béguin, Mathieu Bertrand, Torben Pöpplau, Jakob Reichel The advent of alkaline-earth-like atoms with ultranarrow optical transitions has opened new avenues both in the fundamental study of quantum gases and for the development of state-of-the-art atomic sensors. In recent years, optical clocks based on Sr or Yb have reached unprecedented stability and accuracy at the 10$^{\mathrm{-18\thinspace }}$level. However, to date, such clocks are ultimately limited by the quantum projection noise due to the absence of correlations between the different atoms. The implementation of quantum metrology schemes using many-body correlated atomic states allows to go around this limitation. A promising path to quantum metrology with neutral atoms is the generation of correlated states using cavity quantum electrodynamics (cQED) methods. In this direction, we present a compact and efficient cQED experiment combining ultracold strontium atoms and high finesse optical micro-cavities. [Preview Abstract] |
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S01.00094: Spin dynamics of single erbium ions Mouktik Raha, Christopher Phenicie, Alan Dibos, Songtao Chen, Jeffrey Thompson Single Er$^{\mathrm{3+\thinspace }}$ions in solid-state hosts are promising single photon sources and quantum memories for quantum repeaters, because of their optical transition at 1.5 $\mu $m in the telecom C-band where fiber transmission losses are minimized. The central challenge of this approach is the low natural photon emission rate resulting from the dipole-forbidden nature of the 1.5 $\mu $m transition. We have demonstrated that this can be overcome by integrating the ions in a low loss, small mode-volume silicon nanophotonic cavity and Purcell enhancing the emission rate by over a factor of 650 [1], enabling the optical observation of single Er$^{\mathrm{3+}}$ ions for the first time. We will also discuss ongoing work to probe the dynamics of the Er$^{\mathrm{3+}}$ ions' spins and generate spin-photon entanglement, as well as studies of the interactions between nearby Er$^{\mathrm{3+}}$ ions in dense clusters. These results will pave the way towards developing scalable, long-distance quantum networks based on silicon nanophotonics and Er$^{\mathrm{3+}}$ ions. \newline [1] A. M. Dibos, M. Raha, C. M. Phenicie, J. D. Thompson, Phys. Rev. Lett. 120, 243601 (2018) [Preview Abstract] |
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S01.00095: \textbf{Convenient fiber laser sources for use in atomic physics} Ronnie Currey, Garnet Cameron, Erin Thornton, Ali Khademian, David Shiner The evolution of rare-earth doped fiber lasers has had an impact on developing convenient laser sources. These sources can provide high power single transverse modes with near Gaussian beam shape from single mode double clad fibers. We have been interested in building Thulium (Tm) doped fiber lasers designed for operation at 2058 nm and Ytterbium (Yb) doped fiber lasers at 1083 nm for studying the helium atom. Fiber lasers can be pumped by very reliable and low-cost high-power fiber coupled solid state lasers operating at 920, 975 and 793 nm. The components of our laser systems are readily available and cost effective, in particular the technology of fiber Bragg gratings (FBG) provides laser cavities inside fiber glass with minimum cavity loss that is a critical factor for efficiency. We will discuss our development and characterization of a 2058 nm Tm doped fiber laser with an output power of over 2 W and our development and characterization of a Yb doped laser at 1083 nm with an output power of over 20 W. Future development includes a 1083 nm single frequency Yb fiber laser. These different laser sources operating in the 1 $\mu $m to 2 $\mu $m regime give reliable cost-effective solutions to driving helium transitions. [Preview Abstract] |
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S01.00096: High-Bandwidth Force Sensing with Optical Cavities Benjamin Reschovsky, Akobuije Chijioke We present two methods for tracking high slew-rate, GHz-amplitude frequency shifts of optical cavities. We are motivated by the use of optical cavities for rapid ($\simeq 10$ kHz bandwidth) sensing of macroscale ($\simeq 100$ N) dynamic forces (e.g. impacts). The first method relies on a Pound-Drever-Hall frequency lock using feedback to a single-sideband modulator to achieve a large dynamic-range with fast locking bandwidth ($> 1$ MHz). The second method uses a dense frequency comb generated by an electro-optic modulator to simultaneously probe a wide ($\simeq 1$ GHz) frequency span. [Preview Abstract] |
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S01.00097: Generalized correlation induced tunneling gate and its application in deterministic Bell-basis measurement Xing Deng, Lushuai Cao, Yaoyao Xu, Xiaochun Duan A new type of quantum gate is designed for qubits encoded in the orbital degree of freedom of ultracold lattice atoms. This quantum gate is based on the so-called correlation induced co-tunneling of two atoms confined in two neighbor sites of an optical lattice and occupying the s- and p-orbital of the site. This gate can generate any of the four Bell states of the two qubits from a component of the corresponding Bell state. Moreover, this gate can also map the four Bell states to different detectable states, and realize deterministic full Bell-basis measurement. [Preview Abstract] |
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S01.00098: Microwave-to-optical transduction and quantum memory in Rb vapors Andrei Tretiakov, Timothy Lee, Clinton Potts, John Davis, Lindsay LeBlanc Quantum memory, which stores quantum information and retrieves it on demand, is an essential part of a quantum computer. Working with signals at microwave frequencies is of particular interest since it is the range of common quantum processors, i.e. superconducting devices and highly-excited atoms. On the other hand, for efficient transfer of a signal, optical wavelengths are preferable. In this project, we study the interaction between a rubidium-87 vapor and an oscillating magnetic field inside a high-Q microwave resonator for quantum memory and wavelength conversion applications. First, we focus on demonstrating microwave-to-optical signal conversion in warm vapor using nonlinear wave-mixing or adiabatic transfer, as well as proof-of-principle storage protocols. Finally, we consider repeating these experiments using an ultracold gas, where the microwave resonator will be placed inside our ultracold quantum gases apparatus under ultra-high vacuum conditions. Working in the ultracold regime increases the time during which the atoms maintain their quantum states, which will increase the efficiency of the transduction protocols. [Preview Abstract] |
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S01.00099: Towards Quantum Simulation of Light-Matter Interfaces with Strontium Atoms in Optical Lattices Neven \v{S}anti\'{c}, Andr\'e Heinz, Annie Jihyun Park, Ettiene Staub, Rudolf Haindl, Stepan Snigirev, Jean Dalibard, Immanuel Bloch, Sebastian Blatt In the last two decades, quantum simulators based on ultracold atoms in optical lattices have successfully emulated strongly correlated condensed matter systems. With the recent development of quantum gas microscopes, these quantum simulators can now control such systems with single-site resolution. Within the same time period, atomic clocks have also started to take advantage of optical lattices by trapping alkaline earth metal atoms such as Sr, and interrogating them with precision and accuracy at the $10^{-18}$ level. Here, we report on progress towards a new quantum simulator that combines quantum gas microscopy with optical lattice clock technology. We aim to trap ultracold Sr atoms in large-mode-volume and state-dependent optical lattices to emulate strongly-coupled light-matter-interfaces in parameter regimes that are unattainable in real photonic systems. We also report on a narrow-line magneto-optical trapping technique that outperforms standard techniques in terms of speed, robustness, and capture fraction. [Preview Abstract] |
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S01.00100: A quantum-classical hybrid variational algorithm using trapped ions Antonios Kyprianidis, Guido Pagano, Patrick Becker, Katherine Collins, Harvey B. Kaplan, Wen-Lin Tan, Aniruddha Bapat, Lucas Brady, Alexey V. Gorshkov, Stephen Jordan, Christopher Monroe Trapped atomic ions are an excellent platform for probing dynamics of many-body systems, allowing the study of quantum magnetism models both in equilibrium and after a quantum quench. We use chains of 171Yb$+$ ions confined in a rf Paul trap to simulate the transverse field Ising model with tunable long-range interactions, generated with spin-dependent optical dipole forces. Experiments are run in two quantum simulators operating at room and cryogenic temperature, respectively. Our platform is used to implement Quantum approximate optimization algorithms [1] and to study confinement of low-energy quasi-particles after a quantum quench [2]. [1] Farhi \textit{et al}, arXiv:1602.07674 [quant-ph] [2] Liu \textit{et al, }arXiv:1810.02365 [cond-mat.quant-gas] [Preview Abstract] |
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S01.00101: Stabilizing a Quantum Photonic Many-Body State Brendan Saxberg, Ruichao Ma, Clai Owens, David Schuster, Jonathan Simon Synthetic photonic systems are a promising platform for new physics in the regime of strongly interacting and highly correlated quantum materials. We build a 1D Bose-Hubbard lattice for photons where capacitively coupled transmon qubits serve as lattice sites and the transmon's anharmonicity mediates strong photon-photon interactions. However, loss present in photonic platforms makes many-body quantum state preparation on large systems problematic. To solve this we use reservoir engineering. We couple our lattice to an autonomous stabilizer -- a lattice site (coupled to a resonator) that is continuously driven into the n$=$1 excited state. This scheme stabilizes the Mott phase, and indeed any many-body target state, so long as the phases are incompressible with respect to photon number. Individual readout resonators allow site-, time-, and occupancy- resolved microscopy of the photonic lattice. Recent improvements to our experiment will allow multi-site correlation measurements - potentially revealing the intricate interplay of correlations, entanglement and thermalization in these driven-dissipative systems. [Preview Abstract] |
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S01.00102: Stern-Gerlach detection of neutral atom qubits in a state dependent optical lattice Felipe Giraldo Mejia, Aishwarya Kumar, Tsung-Yao Wu, David Weiss Using a technique conceptually similar to the Stern-Gerlach experiment [Z. Phys. 9, 349-352 (1922)], we have developed a high-fidelity state measurement for neutral atom qubits that induces no loss. The measurement fidelity of 0.9994 has roughly 20 times lower error than any previous state detection for neutral atom arrays [Phys. Rev. Lett. 119, 180504 (2017), Phys. Rev. Lett. 119, 180503 (2017)], and also significantly exceeds the fidelity of any other qubit array (including ion and superconducting qubit arrays) with more than four qubits [Nature 536, 63-66 (2016), Phys. Rev. Lett. 112, 190504 (2014)]. The measurement is based on coherent spatial splitting of the atoms' wavefunctions, but using state-dependent light traps instead of magnetic fields as in the original Stern-Gerlach experiment. Our measurement causes no loss and the fidelity is basically independent of the number of qubits. We demonstrate here that we can reuse the atoms after detection even when background gas collisions have caused atom losses, by using our 3D atom sorting [Nature 561, 83--87 (2018)]. [Preview Abstract] |
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S01.00103: Progress toward scalable quantum computing at Honeywell Quantum Solutions John Gaebler, Bryce Bjork, Dan Stack, Matthew Swallows, Maya Fabrikant, Adam Reed, Ben Spaun, Juan Pino, Joan Dreiling, Caroline Figgatt Honeywell Quantum Solutions (HQS) is pursuing a scalable quantum computing architecture based on trapped atomic ions. To this end, HQS is developing a broad array of enabling technologies and capabilities, including demonstrations of high-fidelity single- and two-qubit gates, fast ion transport and ion crystal reconfiguration, parallel multi-zone laser addressing of trapped ion qubits, and the design and microfabrication of state-of-the-art multi-zone ion traps. We will report recent progress on these and other fronts. [Preview Abstract] |
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S01.00104: A transportable absolute Quantum Gravimeter employing Bose-Einstein condensates Sven Abend, Nina Heine, Maral Sahelgozin, Jonas Matthias, Waldemar Herr, Ludger Timmen, Juergen Mueller, Ernst M. Rasel The transportable Quantum Gravimeter QG-1 is designed to acquire absolute values for local gravity, while maintaining long-term stability and providing the capability for mobile deployments. The device utilizes atom interferometry with Bose-Einstein condensates (BECs). The BECs act as ideal test masses when released into free fall and can be precisely controlled. In general, all atom gravimeters share the characteristic of not suffering from wear and tear of a corner cube and thereby inherently suppress the need for recalibration of the device. Additionally, employing magnetically lensed BECs in contrast to thermal atoms used in the current generation of atom gravimeters significantly reduces the expansion rate of the ensemble and thereby the systematic uncertainties related to wavefront aberrations and the Coriolis force. In order to apply these advantages for mobile operation a compact atom- chip setup providing a high BEC flux, a fiber based frequency doubled telecom laser system and compact electronics were developed. We focus on the principle of operation including the recent progress and the perspectives to overcome the leading order limitations of state-of-the-art atom gravimeters. [Preview Abstract] |
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S01.00105: Progress towards correlated defect magnetometry with nitrogen vacancy canters in diamond Aedan Gardill, Matthew Cambria, Phillip Flinchum, Wangping Ren, Shimon Kolkowitz Nanosocale metrology has applications in fields ranging from industrial fabrication to biophysics to the study of complex condensed matter systems. Color center defects in diamond enable local measurements of material properties and dynamics at the nanometer scale. We report recent progress towards the use of nitrogen vacancy (NV) centers in diamond as local nanoscale probes, including experimental results from an ongoing study of relaxation and decoherence of individual NV centers in nanodiamonds. We will discuss the prospects for novel subdiffraction limited magnetic microscopy and correlated defect magnetometry techniques. Finally, we will present plans for utilizing NV centers to study the microscopic nature of decoherence in promising qubit platforms as a first step towards a next generation of ``decoherence-free'' quantum technologies. [Preview Abstract] |
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S01.00106: Quantum phase tracking in a truncated SU(1,1) interferometer Prasoon Gupta, Rory W. Speirs, Paul D. Lett, N/A N/A We perform a phase tracking experiment in a truncated SU(1,1) interferometer. Here we track the phase of light inside the interferometer. We show the theoretical analysis of the improvement in the phase tracking error with the truncated SU(1,1) interferometer over what is classically possible using a coherent beam in a truncated version of a Mach-Zehnder interferometer. In our experimental setup, we build a truncated SU(1,1) interferometer by producing a two-mode squeezed light using a 4-wave mixing (4WM) process in a hot Rubidium vapor cell. We perform joint homodyne detection on the two-mode squeezed beams to get the phase information. Theoretically, we look at the improvement in the phase tracking error with the gain of the 4WM process, optical loss and the squeezing measured in the two- mode squeezed light. We use a Kalman filter to process the electrical signal from the joint homodyne detector and obtain the phase information. We feed this phase information back to the joint homodyne detector to track the phase of the two-mode squeezed light inside the truncated SU(1,1) interferometer. [Preview Abstract] |
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S01.00107: Characterization of Trapped Ion Slow Light John Hannegan, James Siverns, Qudsia Quraishi Building future hybrid quantum networks will require interfacing different types of quantum systems. We present our work demonstrating slow light in a rubidium vapor using photons from a single trapped barium ion [1]. Using a simplified single beam path approach [2] we obtain tunable single photon delays. Using quantum frequency conversion we bridge the spectral gap between barium ion photons and neutral rubidium [3]. We discuss the signal-to-noise, tunability of conversion, vapor cell coating, and current limitations. This work constitutes the first demonstration of an interaction between photons emitted from a single trapped ion and neutral atoms, laying the groundwork for future ion-neutral hybrid photonic interactions. [1] J. D. Siverns, J. Hannegan and Q. Quraishi, arXiv:1808.07928 (2018). [2] R. M. Camacho, M. V. Pack and J. C. Howell, Phys. Rev. A, 73:063812 (2006). [3] J. D. Siverns, J. Hannegan and Q. Quraishi, Phys. Rev. Applied 11, 014044 (2019). [Preview Abstract] |
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S01.00108: Molecules Functionalized with Optical Cycling Centers Changling Zhao, Seejia Yu, Ashley Shin, Xueping Long, Timothy Atallah, Justin Caram, Wesley Campbell Repeatable, state-selective optical transitions are widely used for state preparation and measurement of qubits hosted by trapped atoms. Due to the vibrational structure that is introduced when trying to apply this technique to molecules, optical cycling is typically unavailable. Inspired by the recent experimental demonstrations on laser cooling of polyatomic molecules that contain an Optical Cycling Center (OCC) in the form of a bonded alkaline earth atom \cite{Kozyryev2017, Kozyryev2016b, Kozyryev2016c}, we propose building a candidate quantum system consisting of assembled monovalent molecules of alkaline-earth (AE)-oxide that are bond to a surface. These surface-bond molecules will be functionalized with alkaline earth OCCs to endow them with the ability for fast and high-fidelity qubit operations and \textit{in-situ} coherent transport of quantum information. We report our current progress on synthesizing molecules with OCCs, and observing and characterizing their spectroscopic properties. [Preview Abstract] |
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S01.00109: DEGENERATE GASES AND MANY-BODY PHYSICS |
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S01.00110: Bose Fireworks Trilogy Zhendong Zhang, Kai-Xuan Yao, Lei Feng, Jiazhong Hu, Cheng Chin Since the first observation of Bose Fireworks from atomic condensates with modulated interactions, many intriguing features have been identified. Our recent investigation on their phase coherence, temporal reversibility and the density wave order offer new insight into the origin and evolution of firework emission. We study the phase coherence by a two-stage modulation that emits and interferes two sets of fireworks. By a sudden quench of the modulation phase, we show that the firework emission can be partially reversed. Moreover, we find a density wave order that appears prior to the emission due to the interference of matterwaves with the condensate. From the above works, we present our latest picture of the firework dynamics in three chronological steps: density wave formation, near-field interference, and far-field thermal radiation. [Preview Abstract] |
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S01.00111: Photoassociation and Isotope shift spectroscopy with ultracold Strontium Ananya Sitaram, Benjamin Reschovsky, Neal Pisenti, Hirokazu Miyake, Peter Elgee, Nicholas Mennona, Gretchen Campbell Strontium makes an excellent candidate for studies in precision measurement and quantum simulation because of its ultra-narrow line used in atomic clocks and its many stable isotopes. We will present our recent measurement of photoassociation resonances near the $^1$S$_0$-$^3$P$_1$ intercombination line, as well as a recent measurement of the isotope shifts for both the $^1$S$_0$-$^3$P$_1$ and $^1$S$_0$-$^3$P$_0$ lines. For the photoassociation measurement, we have investigated the mass-scaling behavior of resonances relative to the $^3$P$_1$ state in bosonic strontium and measured a number of bound states for $^{84}$Sr and $^{86}$Sr. Isotope shifts were measured between all stable isotopes of strontium relative to $^{88}$Sr, allowing for a King Plot analysis. Finally, we will report on progress made in building a new ultracold strontium experiment. Improvements include implementing a Bitter coil design for the MOT, allowing us to achieve moderately high magnetic fields with easy and effective water cooling, and a newly designed vacuum chamber. [Preview Abstract] |
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S01.00112: A Numerical Study of Many-Body Localization using LOBPCG Gregory D. Meyer, Roel Van Beeumen, Chao Yang, Norman Y. Yao Many-body localization (MBL) has generated excitement in the past decade as a fundamentally out-of-equilibrium state of quantum matter. Numerical studies have been a crucial tool for exploring MBL. For example, computing the so-called level statistics of eigenenergies by exactly diagonalizing the Hamiltonian is a common way of identifying localization. However, such exact diagonalization of an exponentially large Hamiltonian is tremendously challenging. Iterative solvers like Lanczos help with this problem by reducing memory and computation costs, but to find interior eigenvalues they must operate on a transformed matrix which is costly to compute. To avoid these costs, we apply the LOBPCG eigensolver to only the matrices $H$ and $H^2$, reducing memory costs significantly. In this scenario we are able to run all computations without ever explicitly storing the Hamiltonian in memory (matrix-free), allowing the solver to run on a single compute node for system sizes up to $L=28$ spins. By using MPI for inter-node communication, we are able to push even further. Our new solver has the potential to yield insight into new MBL systems, including localization in two dimensions. [Preview Abstract] |
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S01.00113: Improved FPGA-Controlled Microwave Source for Cold Atom Experiments Isaiah Morgenstern, Shan Zhong, Qimin Zhang, Arne Schwettmann We present our updated FPGA-controlled microwave source for controlling the time-dependent microwave-dressing of the ground state hyperfine levels of a Bose-Einstein condensate. The updated design utilizes commercial FPGA, DDS, and LCD boards for easy setup of the system. The FPGA control allows versatile programming of fast, arbitrary, time-dependent changes of amplitudes, phases, and frequencies. A 20 W amplifier increases the signal strength to the amplitudes necessary for microwave dressing of cold atoms. A simple homebuilt antenna inside the vacuum chamber irradiates the atoms. The microwave source is modular, so it can be easily reprogrammed and adjusted to fit a wide variety of experimental setups. [Preview Abstract] |
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S01.00114: A new apparatus for quantum simulation with ultracold dipolar erbium atoms Bojeong Seo, Ziting Chen, Yeeming Tso, Weijun Yuan, Peng Chen, Shenwang Du, Gyu-boong Jo Recently Lanthanide atoms such as dysprosium and erbium have attracted significant attention in quantum simulation with ultracold atoms due to their large magnetic moment and meta-stable excited states. Here, we present our on-going efforts for developing a versatile erbium apparatus in which various exotic states of matter, such as quantum droplets, can be emulated. Slow erbium atoms generated by a spin-flip Zeeman slower are trapped by a magneto-optical trap (MOT). We implement a bi-chromatic MOT, consisting of singlet ($4f^{12}6s^2$ $^3H_6\to$ $4f^{12} (^3H_6)6s6p(^1P_1)$) and triplet ($4f^{12}6s^2$ $^3H_6\to$ $4f^{12} (^3H_6)6s6p(^3P_1)$) transitions, which increases the repetition rate of experiment. We will discuss experimental details that produce a degenerate quantum gas of erbium atoms in the apparatus. [Preview Abstract] |
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S01.00115: Dissipative dynamics of interacting Bosons Jian Jiang, Christian Baals, Jens Benary, Herwig Ott We study the non-equilibrium dynamics of ultracold Bose gases using a scanning electron microscope. In the first part of this poster, we report an experiment that demonstrates coherent perfect absorption (CPA) for nonlinear matter waves using an atomic Bose-Einstein condensate (BEC) of Rb-87 in a one-dimensional optical lattice with an absorbing lattice site. [1] This absorption is tailored via an electron beam which locally induces losses. In the second part, we introduce our updated experimental setup in which an objective with high numerical aperture is embedded. In this setup, an arbitrary optical potential can be projected onto a BEC through the objective such that interesting topics, e.g. dark solitons generated by phase imprinting and stabilized by local dissipation, quantum transport in ultracold atoms [2], can be studied. References [1] Sci. Adv. 4, eaat6539 (2018) [2] Nature Phys. 11, 998-1004 (2015) [Preview Abstract] |
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S01.00116: Neural Network Solver for Multi-Component Bose Einstein Condensates John Heropoulos, Seth Rittenhouse We present an approach to using neural networks in order to find the ground state of a multi-component Bose-Einstein condensate. The variational theorem in quantum mechanics states that the energy of a trial wavefunction cannot be less than the energy of the true ground state wavefunction. We use a feed-forward neural network with a numerical grid input layer, multiple hidden layers, an output layer which is our trial wave function, and a loss function equal to the energy of the system. After iterative training, the neural network outputs the ground state wave function with an energy equal to the ground state energy of the system. We then use the Neural Network architecture to describe a 2D Bose-Einstein condensate with state dependent contact and long-range interactions. [Preview Abstract] |
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S01.00117: Dissipation effects to the disintegration of a multiply-charged quantum vortex Yucong Cai, Ikaika McKeague-McFadden, E. Carlo Samson Using 2D numerical simulations based on the Gross-Pitaevskii equation (GPE), we study the quantum vortices created by a blue-detuned optical beam that is dragged across a highly oblate Bose-Einstein condensate (BEC) in a spiral trajectory. The dependence of the generated vorticity to the beam's optical power and to the trajectory parameters was analyzed. Dissipation was introduced to the simulations by adding a phenomenological damping term to the GPE. We explored how dissipation affects the vortex dynamics after ramping off the optical beam, wherein we observed spatial clustering of vortices and co-rotating vortices. The break up dynamics of the giant vortex exhibited a transition from a symmetric configuration of single vortices to a disordered arrangement. The observed dissipation effects may help understand the role of thermal/background atoms to the onset of turbulence in BECs. [Preview Abstract] |
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S01.00118: Probing non-equilibrium dynamics with homogeneous two-dimensional atomic quantum gases Cheng-An Chen, Chen-Lung Hung Probing non-equilibrium dynamics in a trapped, inhomogeneous atomic quantum gas can be a challenging task because coexisting mass transport and spreading of quantum correlations often make the problem intractable. By removing density inhomogeneity in an atomic quantum gas and employing local control of chemical potential as well as interaction parameters, it is possible to perform quasi-particle control, initiate and probe collective quantum dynamics without or with a controlled mass flow. We report progress toward quasi-particle control and non-equilibrium dynamics study in a homogeneous two-dimensional quantum gas. We initiate the experiment by loading ultracold cesium atoms into a quasi two-dimensional (2D) box trap formed by an all blue-detuned optical potential. We employ the control of quasi-particles, or more precisely phonons, in a 2D superfluid by spatiotemporal modulation of the atomic interaction, via an optical Feshbach addressing technique. We discuss our scheme of engineering phonon transport, manipulating a phononic band gap crystal in a quantum gas, as well as phonon-pair generation and entanglement detection. [Preview Abstract] |
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S01.00119: Many-Body Dynamical Phase Separation and Pattern Formation in Ultracold Fermionic Mixtures Simeon Mistakidis, Jennifer Erdmann, Peter Schmelcher We explore the correlated quench dynamics of ultracold fermionic mixtures consisting of a majority and an impurity atom being confined in a double-well. It is shown that quenching the interspecies repulsion towards the strongly interacting regime the two species phase separate within the Hartree-Fock approximation, while remaining miscible in the many-body treatment. Despite their miscible character on the one-body level the two species are found to be strongly correlated and exhibit a phase separation on the two-body level that suggests the anti-ferromagnetic behavior of the mixture. On the other hand, ramping down the barrier of the double-well induces a counterflow dynamics of the species which form strongly correlated dark-bright soliton like entities. By increasing the concentration of the impurities we showcase signatures of the induced interactions in several observables and the dynamical formation of bound states. Finally, we simulate in-situ single-shot measurements and showcase how our findings can be retrieved by averaging over a sample of single-shot images. [Preview Abstract] |
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S01.00120: Manipulating fermionic superfluids with arbitrary optical potentials Giulia Del Pace, Woojin Kwon, Riccardo Panza, Massimo Inguscio, Francesco Scazza, Giacomo Roati We report on our recent experimental results on manipulating fermionic superfluids with arbitrary optical potentials, realized by the combination of a high-resolution imaging and a Digital Micromirror Device (DMD). In particular, we demonstrate a new fully DMD-based technique that allows us to manipulate the phase of fermionic superfluids prepared in a Josephson-like geometry. We can dynamically control the relative phase between the two superfluid reservoirs by illuminating one of them with an appropriate homogeneous pattern of light. The imprinted phase is characterized by studying the interference fringes after a time of flight expansion and we find a monotonic behavior of the imprinted phase as a function of the pulse parameter. Moreover, we studied DC Josephson effect when a constant and homogeneous light shift is imprinted to one of the two reservoirs, finding that the oscillation frequency of the system is proportional to the applied light shift. [Preview Abstract] |
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S01.00121: Non-equilibrium dynamics of a superfluid Fermi gas with time-periodic modulation: Higgs mode and higher-order harmonic excitation Kui-Tian Xi, Qijin Chen, Gentaro Watanabe Motivated by the recent experiment on observation of the Higgs mode in a strongly interacting superfluid Fermi gas [A. Behrle \textit{et al}., Nat. Phys. \textbf{14}, 781 (2018)], we study the non-equilibrium dynamics of a superfluid Fermi gas with a time-periodic modulation in the BCS-BEC crossover by solving the time-dependent Bogoliubov-de Gennes (BdG) equations. By tuning the modulation amplitude and frequency of the coupling constant, we have demonstrated that the Higgs mode can be excited with the time-periodic modulation. For a small modulation amplitude, the long-lived Higgs mode comparing to the current experimental result exists when the modulation frequency is slightly red-detuned. When the modulation frequency is blue-detuned, the single-particle excitation appears along with the Higgs mode. For a large modulation amplitude, the higher-order harmonic excitation is generated due to the nonlinearity. The exploration of other optimal ways of exciting the Higgs mode in a superfluid Fermi gas is also discussed. [Preview Abstract] |
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S01.00122: Suppression of Inelastic Loss Near a P-Wave Resonance for Fermions in 1D Andrew Marcum, Arif Mawardi Ismail, Francisco Fonta, Kenneth O'Hara Degenerate Fermi gases with p-wave interactions hold many exciting prospects for observing novel quantum phases of matter. Unfortunately, the enhancement of the p-wave interaction strength near a Feshbach resonance has typically been accompanied by a corresponding strong enhancement of two-body and three-body inelastic collision rates which leads to significant atom loss on short time scales. Here we study two-body relaxation and three-body recombination in the vicinity of a p-wave Feshbach resonance when the fermionic atoms are confined to one dimension. In both cases we find that inelastic loss is significantly suppressed but by two quite distinct mechanisms. In the case of two-body relaxation, we find that the two-body decay rate constant for an uncorrelated gas is relatively unaffected by the 1D confinement. However, after an initial rapid decay, correlations in the gas develop that inhibit further loss from the 1D gas. In the case of three-body recombination, the inelastic decay rate constant itself is suppressed by over an order of magnitude when comparing the rate constant in 3D to that in 1D. Understanding and leveraging these mechanisms for suppression of inelastic loss may open the possibility of realizing odd-wave superfluid pairing in a dilute Fermi gas. [Preview Abstract] |
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S01.00123: Universal dynamical scaling of two-dimensional vortices in a strongly interacting fermionic superfluid Xiang-Pei Liu, Xing-Can Yao, Youjin Deng, Xiao-Qiong Wang, Yu-Xuan Wang, Chun-Jiong Huang, Xiaopeng Li, Yu-Ao Chen, Jian-Wei Pan Dynamical formation and annihilation of vortices and antivortices play a key role in the celebrated Berezinskii-Kosterlitz-Thouless (BKT) theory, a universal topological mechanism describing exotic states of matter in low dimensions. Here we study the annihilation dynamics of a large number of vortices and antivortices generated by thermally quenching a fermionic superfluid of Li6 atoms in an oblate optical geometry. Universal algebraic scaling laws in both time and space are experimentally revealed over a wide interaction range, from the attractive to the repulsive side across the Feshbach resonance, and further found to agree with a Glauber dynamics in Monte Carlo simulation of the classical XY model and with field-theoretical calculations. Our work provides a direct demonstration of the universal vortex dynamics underlying the BKT theory. [Preview Abstract] |
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S01.00124: Spin-flip dynamics of a radiofrequency-dressed ultracold Fermi gas Yun Long, Feng Xiong, Colin Parker Ultracold fermionic spin mixtures serve as a basic model for itinerant material systems with magnetic and superfluid properties. In such systems, a comparison of basic properties such as magnetic susceptibility may help elucidate the connection with more complex systems such as cuprate superconductors. Towards this end, we investigate methods to generate equilibrium spin imbalances using radiofrequency dressing in an ultracold lithium-6 gas. We apply a magnetic gradient in the presence of radiofrequency dressing to create a spatially-varying matrix element coupling the two dressed states. The second lowest, rather than the absolute lowest, pair of spin states are chosen for their greater magnetic sensitivity. We emply a phase-contrast imaging system to directly measure the spin difference. [Preview Abstract] |
(Author Not Attending)
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S01.00125: Induced transitions in the attractive Bose-Hubbard model Lev Khaykovich, Fatema Hamodi We study induced transitions between different energy levels in the one-dimensional attractive Bose-Hubbard model with periodic boundary conditions. The initial eigenstates of the model are found by the exact diagonalization of the Bose-Hubbard Hamiltonian in the limit of small systems. Then, we drive transitions between the eigenstates by inducing a weak modulation of the tunnelling rate. The knowledge of exact eigenstates allows us to identify the selection rules for transitions between the different eigenstates. One obvious selection rule is related to the translation symmetry of the system. In addition, we identify a subspace in the total Hilbert space where parity symmetry dictates another and less obvious selection rule. We then show that in the strongly interacting limit this selection rule has implications on the entire Hilbert space. We discuss its signatures on the system's dynamics and consider how it can be observed experimentally with ultracold atoms. [Preview Abstract] |
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S01.00126: Quantum gas microscopy of tailored few-body systems Andreas Kerkmann, Michael Hagemann, Mathis Fischer, Christof Weitenberg We are setting up a new quantum gas microscope for the detection of degenerate samples of \textsuperscript{6}Li/\textsuperscript{7}Li atoms to study strong correlations in small quantum systems.\\ Our design consists of a compact 2D-/ 3D-MOT loading scheme, a lambda-enhanced gray molasses and an all-optical approach for the preparation of degenerate samples. A red-detuned accordion lattice brings these samples into the two-dimensional regime. We then investigate the possibility of different cooling schemes in a phase-stabilized triangular pinning lattice to collect sufficient fluorescence for single-site imaging.\\ In the future, we will look at few-body systems in specifically tailored optical potentials to study new regimes, e.g., ionization dynamics in artificial atoms or fractional Quantum Hall physics in rotating microtraps. In this poster, we provide information about the details of the design, the current status of the experiment and our future plans. [Preview Abstract] |
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S01.00127: Quantum Collective Spin Dynamics of Strontium in Cavity QED Diego Barberena, Robert Lewis-Swan, James Thompson, Ana Maria Rey Recently, a new regime of cavity QED has become amenable to experimental explorations, enabled by the recent developments in implementations with alkaline earth atoms that take advantage of the long lifetimes of their clock transitions and their rich internal structure. In this regime, the atoms are subject to strong exchange interactions and collective superradiant decay, both of them mediated by a single optical cavity mode. Here we report results when the clock transition is also coherently driven by an external field. By computing the time evolution of different spin observables, we show that, in the limit of a large number of particles, the system shows three markedly different dynamical behaviors as a function of the drive strength. We also compute the time evolution of spin squeezing to assess the metrological usefulness of the system. We then report new investigations when a shorter lived but stronger transition is used. Here we analyze the new effects that arise because the cavity photons cannot be adiabatically eliminated and play a dynamically important role. We study how those effects can be used for sensing. [Preview Abstract] |
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S01.00128: Universal defect formation dynamics in a strongly interacting Fermi gas Bumsuk Ko, Jee Woo Park, Kyuhwan Lee, Yong-il Shin Systems of different microscopic origins exhibit universal properties near a continuous phase transition if they share generic features such as their symmetries and dimensionality. Here, we report the observation of the Kibble-Zurek (KZ) universality in a strongly interacting Fermi gas. In the KZ mechanism, when a system is linearly quenched across the critical point, the universal nature of the dynamics is manifested in a power-law exponent that governs the dependence of the density of spontaneously created defects on the quench rate. By linearly quenching the temperature of an oblate sample of $^{6}$Li atoms near a Feshbach resonance, we create as many as 50 vortices in the sample and demonstrate the characteristic KZ scaling. When the nature of superfluidity is tuned from bosonic to fermionic, the scaling exponent remains constant at a value that is consistent with the prediction of the inhomogeneous KZ mechanism for a harmonically trapped BEC, revealing the underlying $U(1)$ gauge symmetry of the system. However, as the quench rate is increased, the destructive collisions among vortices with opposite sign limit the vortex density to a value that is inversely proportional to the square of the interaction-dependent healing length of the superfluid. [Preview Abstract] |
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S01.00129: Feedback stabilization of a cavity-coupled spin oscillator Jonathan Kohler, Julian Wolf, Johannes Zeiher, Dan Stamper-Kurn Ultracold atoms coupled to optical cavities are an ideal system for studying quantum measurement and control. Through sensitivity to the atomic state, the cavity field can apply coherent backaction, modifying the dynamics of the ensemble. In addition, photons leaking out of the cavity provide real-time information about these dynamics. In this work, we report out-of-equilibrium stabilization of the collective spin of an atomic ensemble, through continuous measurement and autonomous feedback by an optical cavity. For a magnetic field applied at an angle to the cavity axis, dispersive coupling to the cavity provides sensitivity to a combination of the longitudinal and transverse spin. Coherent backaction from this measurement, conditioned by the optical cavity susceptibility, is used to stabilize the collective spin state at an arbitrary energy. We observe real-time energy exchange between the light and spin, recorded in the Stokes and anti-Stokes sidebands of photons leaving the cavity, which reveals stabilization of the spin to an energy controlled by the frequency of the cavity drive. Our results demonstrate the intriguing interplay of measurement and feedback for ultracold atoms in optical cavities and pave the way for future studies of feedback-stabilized spin states. [Preview Abstract] |
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S01.00130: ABSTRACT WITHDRAWN |
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S01.00131: Search For The FFLO Phase In The Dimensional Crossover Of An Imbalanced Fermi Gas Yi Jin, Jacob A. Fry, Eduardo Ibarra G. P., Randall G. Hulet The Fulde--Ferrell--Larkin--Ovchinnikov (FFLO) magnetized superconductor has never been conclusively observed. Theory predicts that FFLO occupies a large region of the one-dimensional (1D) phase diagram and only a small region, if any, in 3D. Long range superfluid order is not supported in 1D and consequently, the FFLO superfluid should be more robust against thermal and quantum fluctuations in 3D. These considerations suggest that the 1D--3D dimensional crossover is a promising region to search for FFLO\footnote{M. M. Parish et al. Phys. Rev. Lett. 99, 250403 (2007).}$^{,}$\footnote{M. C. Revelle et al., Phys. Rev, Lett. 117, 235301 (2016).}. Using a 2D optical lattice, we confine a spin-imbalanced Fermi gas of $^6$Li to 1D tubes. We bring the system to the dimensional crossover by increasing the inter-tube tunneling rate and the interaction strength in the BEC-BCS crossover regime. Observation of spatially periodic domain walls formed by the excess unpaired spins would constitute direct evidence for the FFLO phase. [Preview Abstract] |
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S01.00132: Microscopy of many-body localization in one dimension Joyce Kwan, Matthew Rispoli, Robert Schittko, Sooshin Kim, Alexander Lukin, Julian Leonard, Markus Greiner An interacting quantum system that is subject to disorder may cease to thermalize due to localization of its constituents, thereby marking the breakdown of thermodynamics. We realize such a many-body-localized system in a disordered Bose-Hubbard chain and present studies of its microscopic properties. At strong disorder, we observe that the particles become localized, suppressing transport and preventing the thermalization of subsystems. We measure the development of non-local quantum correlations, whose evolution is consistent with a logarithmic growth of entanglement entropy [1]. At intermediate disorder, we find that the system exhibits critical properties, such as sub-diffusive transport and system-size dependent thermalization. We provide evidence that these dynamics are driven by a network-like structure, which persists in multi-point correlations of high order, and thereby identify the many-body nature of the critical regime [2]. Finally, we study the influence of a thermal bath on many-body localization by connecting the system to a disorder-free region. [1] A. Lukin et al., arXiv: 1805.09819 [2] M. Rispoli et al., arXiv: 1812.06959 [Preview Abstract] |
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S01.00133: Spin- and atom-interactions in multimode cavity QED Ronen Kroeze, Yudan Guo, Jonathan Keeling, Benjamin Lev Optical cavity QED provides a versatile platform with which to explore quantum many-body physics in driven-dissipative systems. Multimode cavities are particularly apt for exploring beyond mean-field physics. After previously having demonstrated strong, tunable range, photon-mediated, atom-atom interactions, we now present three other recent experimental advances. Firstly, we have endowed these interactions with a sign-changing feature. In a confocal cavity, Gouy phase effects result in non-local, sign-changing interactions, and enriched symmetries. We demonstrate this using holographic detection of the cavity emission, after crossing a superradiant, self-organization phase transition. In the same context of a non-equilibrium Dicke-like phase transition, we realize joint spin-spatial (spinor) organization of a two-component Bose-Einstein condensate, as driven by spinor-spinor interactions. Lastly, we present results on dynamical spin-orbit coupling, where a chiral spin spiral emerges. Uniquely, it is quantum fluctuations that drive this spin-orbit coupling, enabling studies of dynamical gauge fields. Together, these advances enable us to explore exotic, strongly correlated systems such as quantum liquid crystals, driven-dissipative spin glasses, and quantum neural networks. [Preview Abstract] |
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S01.00134: ABSTRACT WITHDRAWN |
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S01.00135: AC synthetic gauge potentials in ultracold atoms. Benjamin Smith, Logan Cooke, Taras Hrushevskyi, Lindsay LeBlanc We explore a periodically driven artificial gauge potential in an ultracold quantum gas, and the character of the resulting synthetic electric and magnetic fields. This is done by numerically simulating the Gross-Pitaevskii equation for a Raman-coupled F$=$1 system subject to a modulated two-photon detuning. We consider the effects of driving frequency and amplitude, interactions, and a spatial detuning gradient. This poster will also highlight some of our recent experimental progress and outlook. [Preview Abstract] |
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S01.00136: COLD ATOMS, IONS, MOLECULES, AND PLASMAS |
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S01.00137: Laser induced fluorescence detection of cold formaldehyde on the $\tilde{A}^1A_2\leftarrow\tilde{X}^1A_1\,4_0^1$ electronic transition Martin Ibr\"{u}gger, Maximilian L\"{o}w, Martin Zeppenfeld, Gerhard Rempe Laser induced fluorescence (LIF) is a diverse and powerful tool used in many areas of research. Here, we present a LIF-based detection scheme for our experiments on cold and ultracold formaldehyde~[1]. Molecules are excited via the $\tilde{A}^1A_2\leftarrow\tilde{X}^1A_1\,4_0^1$ electronic transition and the emitted fluorescence photons are focused by a pair of mirrors (covering a solid angle of $\sim$70\%) onto a photomultiplier. The lack of a cycling transition as well as the need for continuous wave operation make stray light suppression a major challenge. This is overcome by extensive beam cleaning and an intricate aperture configuration, thereby reducing stray light by over 6 orders of magnitude. The scheme allows state selective detection of the molecules with discrimination of individual M-sublevels. In combination with a double-pass saturation spectroscopy setup, this enables us to perform precise Stark spectroscopy on the electronic transition, allowing us to determine molecule parameters for the excited electronic state. Furthermore, we are able to measure lifetimes of individual excited rotational states, showing a strong dependence on the rotational quantum numbers.\newline[1] A. Prehn {\sl et al.}, {\sl Phys. Rev. Lett.} {\bf 116}, 063005 (2016) [Preview Abstract] |
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S01.00138: Towards Quantum Gas Microscope for 87Rb-85Rb Mixture Cheng Chen, Chuyang Shen, Xiaoling Wu, Yue Cui, Shen Dong, Meng Khoon Tey, Li You The development of quantum gas microscope has opened the door to study and answer fundamental questions of modern condensed matter physics with ultracold atom experiment. When loaded into a periodic potential, ultracold atomic quantum gases can emulate Hamiltonians of a variety of condensed matter model, such as the bosonic or fermionic Hubbard models, and simulate their equilibrium and dynamical properties. We will report our ongoing experiment aimed at achieving single-site resolved quantum gas microscope using a 87Rb-85Rb mixture in a 2D/3D optical lattice. Our microscope features an off-the-shelf aspherical lens placed inside the vacuum chamber. [Preview Abstract] |
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S01.00139: A Mode Cleaner Cavity for Improved Stability of an Optical Dipole Trap Patrick Bagge, De Luo, Jason H. V. Nguyen, Randall G. Hulet The use of optical dipole traps has become a standard technique to trap ultracold atoms. Generated by a focused, far-detuned laser beam, our single-beam optical dipole trap is intended to be a strictly TEM$_{00}$ mode, as the presence of higher order modes can introduce instabilities in the trap. In particular, the location of the laser beam focus can vary over time when higher-order modes are present. We implement a monolithic mode cleaner cavity designed to pass the TEM$_{00}$ mode and suppress higher-order transverse modes. The cavity consists of four mirrors in a bow-tie configuration and is locked on resonance by using the tilt locking method\footnote{D. Shaddock, M. Gray, and D. McClelland, Opt. Lett. 24, 1499-1501 (1999).}. We characterize the performance of the cavity and its effect in improving the stability of an optical dipole trap used in experiments with bright matter-wave solitons. [Preview Abstract] |
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S01.00140: A reconfigurable blue-detuned lattice for neutral atom quantum computing Trent Graham, Cody Poole, Xiaoyu Jiang, Alphonse Marra, Brandon Grinkemeyer, Garrett Hickman, Josh Cherek, Matthew Ebert, Mark Saffman We present recent progress towards building a neutral atom quantum computer. We use a new design for a blue-detuned optical lattice to trap single Cs atoms. The lattice is created using a combination of diffractive elements and acousto-optic deflectors (AODs) which give a reconfigurable set of cross-hatched lines. By using AODs, we can vary the number of traps and size of the trapping regions as well as eliminate extraneous traps in Talbot planes. Since this trap uses blue-detuned light, it traps both ground state atoms and atoms excited to the Rydberg state; moreover, by tuning the size of the trapping region, we can make the traps ``magic'' for a selected Rydberg state. We use an optical tweezer beam for atom rearrangement. When loading atoms into the array, trap sites randomly contain zero or one atoms. Atoms are then moved between different trapping sites using a red-detuned optical tweezer. Optimal atom rearrangement is calculated using the ``Hungarian Method''. These rearrangement techniques can be used to create defect-free sub-lattices. Lattice atoms can also be used as a reservoir for a set of selected sites. This allows quick replacement of atoms, and increased data rate, without reloading from a MOT. [Preview Abstract] |
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S01.00141: A Laser Cooling Scheme for Ti-like Elements Scott Eustice, Kayleigh Cassella, Dan Stamper-Kurn While immense progress has been made by cooling simple atoms to quantum degeneracy, such as the alkalis, cooling atoms with more internal degrees of freedom will allow the realization of more complicated states of quantum matter. We have identified Ti, Zr, Fe, and Ru as atoms with distinct internal structure compared to already cooled species, that are accessible with standard cooling methods. All have ground states with $L\neq0$, leading to large vector and tensor polarizabilities and thus anisotropic atom-light interactions. They also have low magnetic moments ($\mu=4/3\mu_B$), which limits the dipole-dipole interactions that reduces coherence and the lifetime of spin mixtures in magnetic atoms, Rydberg atoms, and dipolar molecules. We focus on Ti as the target of our initial cooling efforts. While a closed transition does not exist out of the Ti ground state [Ar] $3d^24s^2$ $a^3F_2$, a metastable $3d^34s$ $a^5F_5$ state has a closed and broad transition at 498.1713 nm to the excited $3d^34p$ $y^5G_6$ state. The linewidth of $\Gamma= 2\pi\times 10.51$ MHz will allow us to create a Ti gas at $250$ $\mu$K by using a spin-flip Zeeman slower and a MOT. We report on experimental progress towards a trapped, cold gas of bosonic $^{48}$Ti and future plans to achieve quantum degeneracy. [Preview Abstract] |
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S01.00142: Quantum technology enabled by metalens-trapped single atoms and hot vapor cells Ting-Wei Hsu, Tobias Thiele, Wenqi Zhang, Amit Agrawal, Mark Brown, Chris Kiehl, Cindy Regal We present two recent experiments in the control of single atoms and quantum sensing technology. First, we present advances on generating high NA optical tweezers with dielectric metasurfaces and on trapping of single atom in associated tightly focused traps. With this new technique we are creating a high NA 0.9 optical tweezer with a working distance of 0.7 mm. In contrast to traditional optics, metasurfaces modify the wavefront of the light through a resonance condition of the surface nanostructure. This enables UHV compatible and high NA optics that have essentially zero thickness. In addition, we present experimental results and progress toward creating a sensitive absolute vector magnetometer with atoms. We first determine the polarization ellipse of a microwave field in a self-calibrated way, and then reference an unknown magnetic probe field to this three-dimensional object. Combining this with atoms in hot-vapor cell in a microwave cavity we can create a versatile high sensitivity vector magnetometer. [Preview Abstract] |
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S01.00143: Local spin excitations to probe strongly correlated Fermi gases N. Fredman, W. Morong, B. DeMarco Ultracold Fermi gases trapped in optical lattices are a useful platform for investigating paradigms of strongly correlated electronic solids, such as the Fermi-Hubbard model. We propose probing local transport in a cubic $^{40}$K optical lattice via direct measurements of spin diffusion and relaxation rates. Using tightly focused Raman beams, we will create a spatially localized minority spin component. Diffusion through the majority gas will be observed in real time using spin-resolved imaging. This technique will allow us to study transport in strongly correlated phases and will complement time-of-flight and Fermi gas microscope techniques. We discuss progress towards implementing this technique. [Preview Abstract] |
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S01.00144: Investigating Floquet dynamics in driven Fermi-Hubbard systems Frederik Goerg, Michael Messer, Kilian Sandholzer, Joaquin Minguzzi, Konrad Viebahn, Anne-Sophie Walter, Remi Desbuquois, Tilman Esslinger Strong periodic driving can be used to coherently control the properties of interacting quantum systems and to engineer novel effective Floquet-Hamiltonians, which feature for example topological band structures. We realize a strongly interacting Fermi gas in a periodically driven hexagonal optical lattice and investigate its charge and magnetic properties. When driving at a frequency close to the interaction energy, we show that anti-ferromagnetic correlations can be enhanced or even switched to ferromagnetic ordering. Furthermore, we investigate the Floquet dynamics of the underlying many-body state in the high-frequency and near-resonant driving regimes. We compare the evolution of the double occupation to an equivalent realization in a static lattice as well as to non-equilibrium ab-initio DMFT calculations. This allows to identify timescales on which the system is well described by an effective static Hamiltonian. Moreover, we find that heating and atom loss due to the drive can be strongly suppressed by minimizing the dispersion of higher bands of the underlying hexagonal lattice. With our near-resonant driving scheme, density-dependent dynamical gauge fields can be realized which lead to exotic interacting topological phases. [Preview Abstract] |
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S01.00145: Enhancing Weak Field Atomic Excitation Using an Atomic Array Taylor Patti, Dominik Wild, Mikhail Lukin, Susanne Yelin We examine a mechanism by which the steady-state excitation likelihood of a single target atom in a weak driving field can be enhanced by many orders of magnitude via interaction with a proximal atomic square lattice. This enhancement is highly sensitive to relative atomic linewidth, polarization, and detuning between the impurity atom of interest and those of the array, and can be conceptualized as impurity interaction with array band structure and collective decay modes. Moreover, it is closely correlated with enhanced scattering in the system. In the case of an infinite lattice, we introduce these interactions in terms of the impurity's self-induced energy and Rabi drive, which stem from its interaction with lattice normal modes. In the case of few atoms, we examine the system in the framework of an optical dark state with properties stemming from geometrical symmetry. [Preview Abstract] |
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S01.00146: Numerical simulations of Brownian ratchets in dissipative optical lattices Anthony Rapp, David Cubero, Alex Staron, Ajitha Mithra, Samir Bali Brownian ratchets are promising systems that allow work to be done on nanoscopic level without the need for directed forces. Remarkably, an increase in the noise actually enhances the efficiency of extracting useful work. Dissipative optical lattices are ideal candidates for studying Brownian ratchets because of the flexibility afforded to the experimenter in tuning the noise coupling the system to the environment. We propose to create semi-classical Monte-Carlo simulations to explore parameter space in order to predict conditions which yield efficient ratcheting action, specifically high Peclet numbers. This information is of vital importance for our ongoing experimental efforts to realize high-efficiency Brownian ratchets in cold atoms. [Preview Abstract] |
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S01.00147: Preparation of Atom Transfer to 2D Pinhole Diffraction Trap Array for Quantum Information Applications Justin Jee, Sebastian Pardo, Elliot Lehman, Sergio Aguayo, Glen Gillen, Katharina Gillen-Christandl Quantum computing requires a system of qubits with two distinguishable quantum states. Conditions for successful quantum computer implementation are system scalability, the ability to initialize qubit states, long decoherence times, execution of universal quantum gates, and read out of these states. Neutral atom quantum computers use light patterns to trap neutral atoms and meet all of the above criteria, save scalability, though much progress has recently been made. Our experiment aims to fill and characterize novel atomic dipole traps in the diffraction pattern of a pinhole [1]. The traps will be projected via a lens into the chamber of a magneto-optical trap containing laser cooled atoms [2]. A two-dimensional array of pinholes would create a two-dimensional qubit array that would be suitable for quantum computing [3]. We will present an experiment schematic and progress toward experimentally verifying our simulations of these traps. [1] G. D. Gillen, et al., Phys. Rev. A 73, 013409 (2006), [2] K. Gillen-Christandl, et al., Phys. Rev. A 82, 063420 (2010), [3] K. Gillen-Christandl, et al., Phys. Rev. A 83, 023408 (2011). [Preview Abstract] |
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S01.00148: Quantum emulation with ultracold strontium in dynamically tunable optical potentials Toshihiko Shimasaki, Peter Dotti, Shankari Rajagopal, Ruwan Senaratne, Alec Cao, Roshan Sajjad, David Weld We present the results of experiments using degenerate strontium atoms in various dynamic optical potentials. First, we discuss quantum emulation of ultrafast phenomena [1]. Atoms trapped in a tightly-focused dipole trap are subjected to a time-varying force field to emulate the ultrafast response of bound electrons or nuclei exposed to the electric field of a pulsed laser. This constitutes an unexplored application of quantum simulation techniques, and one which can potentially unite two largely disjoint communities within DAMOP (ultrafast and ultracold). Second, we report results of experiments on strontium atoms in a tunable quasiperiodic optical lattice. Access to a phasonic degree of freedom enables demonstration of a new spectroscopic probe of quantum quasicrystals. Finally, we discuss the future prospect of implementing a Kitaev chain in a quantum gas. [1] R. Senaratne, S. Rajagopal, et al., Nat. Comm. 9, 2065 (2018) [Preview Abstract] |
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S01.00149: Applications of the deformed nucleus of 173Yb+ Conrad Roman, Anthony Ransford, Wesley C. Campbell Trapped $^{173}Yb^+$ ions provide a unique and intriguing opportunity for exploring fundamental atomic physics and quantum information. This $I = 5/2$ isotope of ytterbium has a highly deformed nucleus that has been predicted to lead to dramatic hyperfine induced quenching of certain hyperfine levels in the metastable $^2F_{7/2}$ state. The corresponding decrease in requisite probe laser power that this furnishes may allow for improved operation as an optical atomic clock. Additionally, the $^2F_{7/2}$ state contains 6 magnetic field insensitive “clock states” that can be used as a basis for an SU(6) qudit, with individual state preparation, manipulation, and readout. Precision measurement of hyperfine splittings in the $^2F_{7/2}$ state should be possible at the same level as the ground state, which allows the ion to act as an electron microscope for nuclear electromagnetic moments, in principle containing structure information up to the magnetic 32-pole moment. [Preview Abstract] |
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S01.00150: A versatile platform for segmented blade trap Quanxin Mei, Minglei Cai, Bowen Li, Jun Wang, Yuzi Xu, Xiang Zhang, Zichao Zhou, Luming Duan Trapped ion system is an excellent platform for quantum simulation and quantum computation which enables us to effciently solve certain problems that are not practically feasible using classical computer system. Several setups of segmented blade trap system have been deployed in our lab, focusing on different applications including universal quantum computation and quantum simulation. In our systems, many techniques are utilized to make them more reliable and robust, including the frequency stabilization of 369nm diode laser with nonlinear spectroscopy of Ytterbium ions in a discharge lamp, an integrated control system for automatic ion loading and real-time feedback based on ions status, an efficient simulation program for accurate predictions of our trap potential, and a reliable procedure to design helical resonator accurately with high quality factor over 300. As our system is able to trap tens of ions, multiple ion detection with EMCCD has also been implemented, requiring about 1ms exposition time, and we are testing multiple ion detection with multi-channel PMT. [Preview Abstract] |
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S01.00151: Progress Towards AlH+ Photon Recoil Spectroscopy with Improved Motional State Readout of Barium Ion Qiming Wu, James Dragan, Gregorio Rabelo, Brian Odom With rotational-vibrational ground state cooling of aluminium monohydrate (AlH+) and robust control over Ba+ internal and motional degrees of freedom,\footnote{Lien, et al., \textbf{Nat. Commun.} 5:4783 (2014)} \footnote{Seck, et al., \textbf{Phys. Rev. A} 93, 053415 (2016)} we can perform Photon Recoil Readout (PRR) of AlH+ en route to precision spectroscopy of single-molecule. Taking advantage of the fast cycling molecular electronic transition, repeated photon recoil events will set the ions in a motion dependent on the spectroscopic transition to a long-lived vibrational excited state. Here we present our progress of sympathetic cooling of a single AlH+ to the ground state of motion with a co-trapped Ba+. In addition, we report our improvements on motional-state detection of Ba+. Coherent manipulation is implemented by a far-off-resonant Raman laser driving a red sideband $\pi$ pulse between the two Zeeman sublevels of the $S_{1/2}$ in Ba+. This is followed by a carrier $\pi$ pulse to selectively shelve one spin state from $S_{1/2}$ to $D_{5/2}$, utilizing a narrow-linewidth 1762 nm laser. This new shelving approach is favourable and will improve our detection efficiency to near 100$\%$. [Preview Abstract] |
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S01.00152: Coherent control of angular momentum states in a two-ion Coulomb crystal Neil Glikin, Erik Urban, Sara Mouradian, Hartmut Haeffner Coherent control of the motional modes of trapped-ion Coulomb crystals is fundamental to their versatility as a platform for quantum control. Typically, these modes are well-modeled as harmonic oscillators. We demonstrate the preparation and coherent control of a mode of motion which instead can be described as a 2D rotor. Such control could provide access to rich previously-unexplored dynamics in trapped ions. We realize this system using a surface-electrode Paul trap with annular electrodes to trap two $^{40}$Ca$^+$ ions in a cylindrically symmetric trapping potential, forming a Hamiltonian that is well-modeled as a confined two-dimensional semirigid rotor. The ions are prepared in a high angular momentum state at rotational frequencies on the order of 100 kHz, allowing us to address individual rotational sidebands. Coherent Rabi oscillations on these sidebands demonstrate the creation of superpositions of states separated by up to four angular momentum quanta, with oscillation contrasts exceeding 90\%. Dynamically decoupled Ramsey experiments show coherence times of a few milliseconds, inversely correlated with the size of the angular momentum superposition. [Preview Abstract] |
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S01.00153: Observations and Identification of Extreme Ultraviolet Spectra from Highly-Charged Neodymium Yang Yang, Amy Gall, Samuel Sanders, Chihiro Suzuki, Roshani Silwal, Dipti Goyal, Joseph Tan, Aung Naing, Sean Buechele, Yuri Ralchenko, Endre Takacs We have measured extreme ultraviolet N-, M- and L-shell transitions from highly charged neodymium at the electron beam ion trap facility at the National Institute of Standards and Technology. The electron beam energies were varied between 0.26 keV - 12.02 keV to produce ionization states ranging from Nd$^{\mathrm{22+\thinspace }}$to Nd$^{\mathrm{56+}}$. The spectra were recorded with a flat-field grazing-incidence spectrometer in the wavelength range of 2.5 nm - 23.3 nm. The spectra were recorded with high count rates, leading to accurate line identification measurements for the wide range of Nd charge states. Calibration was performed by using well known lines of ionized Ne, Xe, Fe, O and Ar produced in the EBIT. Our total uncertainties ranged from 0.0007 nm - 0.003 nm and included contributions from estimated systematic uncertainties, statistical uncertainties, and calibration uncertainties. Detailed collisional-radiative (CR) modeling of the non-Maxwellian EBIT plasma was used to create synthetic spectra and help identify lines. We present the Nd spectra with the associated line identifications, including previously observed features, which agree with the existing experimental values. [Preview Abstract] |
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S01.00154: Controlling Feshbach-optimized photoassociation of ultracold atoms with non-resonant laser field Hu Xue-Jin, Hu Zhong-Kun We investigate theoretically the formation of ultracold $^{\mathrm{40}}$K$^{\mathrm{87}}$Rb molecules using Feshbach-optimized photoassociation controlled by non-resonant laser field. A scattering resonance can greatly enhance the photoassociation rate via increasing the number of atom pairs at short interatomic separations. Here a non-resonant laser field is employed to induce the coupling between different partial waves and modify the scattering resonance in their position and width. By tuning the intensity of the non-resonant laser field, the photoassociation rate is enhanced by several orders of magnitude with a fixed magnetic field. The employment of a non-resonant laser field gives an additional approach of photoassociation rate control and is much more feasible for the experiment than a dc electric field. [Preview Abstract] |
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S01.00155: Full quantum-state control of two different atoms in an optical tweezer Kenneth Wang, Lee R. Liu, Yichao Yu, Lewis R. B. Picard, Jonathan D. Hood, Till Rosenband, Kang-Kuen Ni Ultracold polar molecules trapped in optical tweezers have emerged as a candidate for a scalable quantum computer. To controllably create a molecule in an optical tweezer, we will assemble it from single atoms. We demonstrate full quantum state control of individual Na and Cs atoms trapped in optical tweezers. We cool both atoms in their respective tweezers to the three-dimensional motional ground state and then merge them adiabatically into a single tweezer. After merging the atoms, we will perform fully coherent, all optical transfer to the ground molecular bound state. To this end, we first demonstrate fully coherent manipulation of the single atoms. We perform spectroscopy of the NaCs molecular states, and study collisional properties of the single atoms extracting scattering lengths from interaction shifts. [Preview Abstract] |
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S01.00156: Characteristics of atom-molecule elastic scattering Ningyi Du, Bo Gao Through numerical calculations for some typical systems, we explore the general characteristics of low-energy atom-molecule interaction for a molecule in its ground rovibrational state and over a range of energies in which only elastic collision can occur. In particular, we explore the role of the anisotropic part of the atom-molecule potential on both the background and the resonances of their elastic scattering. This work is a part of an exploration related to the application and the further development of multichannel quantum defect theory (MQDT) for atom-molecule interactions. [Preview Abstract] |
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S01.00157: Progress Towards a Magneto-Optical Trap of Polyatomic Molecules Nathaniel Vilas, Louis Baum, Christian Hallas, Debayan Mitra, John Doyle Recent advances in laser cooling and quantum state control of diatomic molecules have made available new experimental platforms for the study of topics ranging from ultra-cold chemistry to quantum simulation of strongly correlated systems. In polyatomic molecules, the complex vibrational and rotational structure generically gives rise to closely spaced opposite parity levels in excited rotational states (for symmetric top molecules) or vibrational bending modes (for linear triatomic molecules). These parity doublets allow full polarization at low electric fields, a significant advantage for precision measurement [1], quantum computation [2], and quantum simulation [3]. Motivated by the promise of these novel systems, we report on progress towards a magneto-optical trap (MOT) of triatomic CaOH molecules. Our apparatus includes a buffer-gas cooling stage followed by 2D magneto-optical compression, laser slowing, and ultimately, trapping in a 3D MOT. The cloud of sub-milliKelvin CaOH molecules achievable in such a MOT will represent a good starting point for loading optical lattices or tweezer arrays for applications in quantum simulation and computation. [1] Kozyryev and Hutzler, PRL 119, 133002 (2017). [2] Yu et. al, in preparation. [3] Wall et. al, New J. Phys. 17, 025001 (2015). [Preview Abstract] |
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S01.00158: Ultracold CaF molecules and Rb atoms in the same trap Hannah Williams, Luke Caldwell, Sarunas Jurgilas, Noah Fitch, Jonas Rodewald, Thomas Wall, Kyle Jarvis, Ben Sauer, Ed Hinds, Michael Tarbutt Several species of ultracold molecules have now been produced. Understanding collisions between ultracold molecules and atoms is an area of great interest. For example, if their properties are favourable, these collisions can be used to sympathetically cool the molecules towards quantum degeneracy. We have built a dual-species magneto-optical trap for CaF molecules and Rb atoms. We will present a study of the collisions between these species, both in the MOT and in a magnetic trap. We will also present our methods for selecting the initial state of the molecular sample and coherently transferring it between different rotational, hyperfine and Zeeman states. [Preview Abstract] |
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S01.00159: Towards two-dimensional quantum gases of ultracold NaCs molecules Niccolo Bigagli, Claire Warner, Aden Lam, Ian Stevenson, Sebastian Will Ultracold gases of dipolar ground state molecules open up the opportunity to study many-body quantum systems with strong long-range interactions and promise to become a novel platform for quantum simulation. We are constructing a new experimental apparatus that is geared towards creating novel quantum phases in two-dimensional gases of ultracold dipolar sodium-cesium molecules. We will use static electric and microwave fields to control the dipolar interactions and engineer optical potentials with a digital micromirror device. In addition, we will implement a high-resolution imaging system to identify 2D quantum phases. In a regime where repulsive dipolar interactions dominate, the emergence of a self-organized crystalline phase is predicted. Upon reducing the interaction strength, a quantum phase transition into a dipolar superfluid is expected, as well as the possible appearance of a supersolid. [Preview Abstract] |
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S01.00160: Co-trapping Ca$^+$ and BH$^+$ Lu Qi, Evan Reed, Nikita Zemlevskiy, Jimmy Shackford, Jyothi Saraladevi, Kenneth Brown BH$^+$ is a candidate molecule for ion direct laser-cooling\footnote{J. H. V. Nguyen, C. R. Viteri, E. G. Hohenstein, C. D. Sherrill, K. R. Brown, and B. Odom, \textbf{New Journal of Physics} 13, 063023 (2011)}. We describe our apparatus for generating BH by ablation of a B target in a hydrogen jet. The BH molecules are then photoionized in a trap containing laser-cooled Ca$^+$. Finally plans and progress on the spectroscopy of sympathetically cooled BH$^+$ are presented. [Preview Abstract] |
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S01.00161: Optical Pumping of $^{\mathrm{27}}$AlD$^{\mathrm{+}}$ Molecules to their Rovibrational Hyperfine Ground State Panpan Huang, Schuyler Kain, Brian Odom Control of the internal degrees of freedom of molecules has important applications in quantum computing, precision spectroscopy, and ultracold chemistry. Molecules can have large electric dipoles compared to atoms. These dipoles can enable the coherent transfer of information within and between molecules, operations relevant to quantum computing. In addition, molecular quantum state control in precision spectroscopy offers one approach to measuring variations of m$_{\mathrm{p}}$/m$_{\mathrm{e}}$ and intrinsic moments of fundamental particles. Molecular state control also offers the potential for insights into chemical phenomena such as the interplay between molecular structure and reaction dynamics. The aforementioned applications require the precise preparation and manipulation of quantum states. Building on previous work on the rovibrational cooling of $^{\mathrm{27}}$AlH$^{\mathrm{+}}$, we propose a method to drive $^{\mathrm{27}}$AlD$^{\mathrm{+}}$ to a specific hyperfine state within the rovibrational ground state using circularly-polarized pulse-shaped UV light. After driving the molecules to the targeted state, the rotational spectrum of the molecule will be acquired and accurate values of its rotational and hyperfine coupling constants will be measured. [Preview Abstract] |
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S01.00162: Ultracold Chemical Reactions of KRb Molecules David Grimes, Yu Liu, Ming-Guang Hu, Andrei Gheorghe, Kang-Kuen Ni Our goal is to understand the details of the quantum dynamics of chemical reactions that take place at ultracold ($< 1$ $\mu$K) temperatures. These dynamics take place on the potential energy surface (PES) of the reaction and fundamentally determine both the products of the chemical reaction and their quantum states. Our experimental approach combines techniques from AOM physics and physical chemistry in order to prepare reactant molecules in a single quantum state and detect product molecule quantum state distributions. We apply this approach to the chemical reaction KRb + KRb $\rightarrow$ K$_2$ + Rb$_2$ in the ultracold regime. [Preview Abstract] |
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S01.00163: Progress toward quantum simulation experiments with a high-performance dysprosium machine William Lunden, Pierre Barral, Michael Cantara, Li Du, Alan O. Jamison, Wolfgang Ketterle We report on progress toward quantum simulation experiments in a new, high-performance dysprosium experiment. We have implemented a number of novel solutions during the construction of this machine which we anticipate will mitigate certain technical barriers in future experiments: a titanium vacuum chamber and non-magnetic surrounding optomechanics to minimize stray magnetic fields; a combination of near-resonant and far-off-resonant slowing light to optimally load our magneto-optical trap; a networked set of laboratory sensors (e.g., temperature, humidity, laser power) whose readings can be stored and investigated for correlations; and custom analog voltage sources with state-of-the-art stability and noise characteristics. [Preview Abstract] |
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S01.00164: Using Rydberg atoms to increase electron coupling strength in ultracold neutral plasmas Duncan Tate, Yin Li, Ethan Crockett, Ryan Newell We have experimentally demonstrated heating and cooling of electrons in an ultracold neutral plasma (UNP) with an initial electron temperature $T_{e,i}$ (determined by the frequency of the ionizing laser) by embedding Rydberg atoms in them in the first 20 ns of their evolution \footnote{Crockett {\it et al.}, {\it Phys. Rev. A}, {\bf 98}, 043431 (2018)}. We have quantified the crossover initial electron temperature, $T_{e,i} = T_{CO}$, for a plasma that is neither heated nor cooled when $N_R$ Rydberg atoms with binding energy $E_b$ are added to a plasma with initial ion number $N_{ion}$. This condition is $k_B T_{CO} \approx 2.7 \times |E_b|$ when $N_R \approx 0.2 \times N_{ion}$. Additionally, we have measured the change in the plasma expansion velocity when $E_b$ does not satisfy the crossover condition for a range of $N_R/N_{ion}$ values. These results are in good agreement with Monte-Carlo calculations. We are also pursuing similar studies, both experimental and numerical, in the regime where $N_R \gg N_{ion}$ to see if the plasma electrons can be cooled sufficiently to increase their coupling to $\Gamma_e \sim 0.5$ in the first 5 $\mu$s of plasma evolution, as predicted by by Pohl {\it et al.} \footnote{T. Pohl {\it et al.}, {\it Eur. Phys. J. D}, {\bf 40}, 45 (2006)}. [Preview Abstract] |
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S01.00165: ABSTRACT WITHDRAWN |
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S01.00166: Equivalence of Many-Mode Floquet Theory to Floquet Theory Adam Poertner, James Martin Many Mode Floquet Theory (MMFT) [T.-S. Ho, S.-I. Chu, and J. V. Tietz, Chem. Phys. Lett. \textbf{96}, 464 (1983)] is an extension of Floquet Theory suitable for solving the time-dependent Schr\"{o}dinger equation when an atom is exposed to multiple time-periodic fields, each with a different periodicity. Despite its success, the conditions for the applicability of MMFT are not well-established, particularly in the case where the frequencies of the applied fields are all low multiples of a common frequency. In this situation, questions arise regarding an over-complete basis. We clarify the applicability of MMFT by demonstrating its equivalence to Floquet Theory through a comparison of time evolution operators in the two approaches. These results are considered in the context of non-resonant dressing of Rydberg atoms with the purpose of reducing their sensitivity to low-frequency electric fields. [D. W. Booth, J. Isaacs, and M. Saffman, Phys. Rev. A \textbf{97}, 012515 (2018)] [Preview Abstract] |
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S01.00167: Towards Quantifying the Impact of State-Mixing on the Rydberg Excitation Blockade Milo Eder, Andrew Lesak, Abby Plone, Aaron Reinhard The Rydberg excitation blockade, a process in which interactions among highly-excited atoms suppress laser excitation, has been at the heart of an impressive array of recent achievements in quantum information and simulation. It has been shown that state-mixing interactions, which result from couplings among multi-particle Rydberg states near Forster resonance, may compromise the effectiveness of the blockade under otherwise favorable conditions$^{\mathrm{\thinspace }}$[1]. We present progress on an experiment in which we seek to quantify the negative impact of state-mixing on the blockade. We use state-selective field ionization spectroscopy to measure, on a shot-by-shot basis, the distribution of Rydberg states populated during narrowband laser excitation of ultracold rubidium atoms. Our method allows us to quantify both the ``mixing-free'' blockade effectiveness, as well as the number of additional Rydberg excitations added by each mixing event. [1] A. Reinhard et al, PRL, 100, 123007 (2008) [Preview Abstract] |
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S01.00168: Driving millimeter-wave transitions in ultracold Sr Rydberg atoms S.K. Kanungo, Y. Lu, R. Ding, J.D. Whalen, H.Y. Rathore, F.B. Dunning, T.C. Killian Transitions between Rydberg states can be driven very efficiently with millimeter-wave radiation. This has been used for coherent control of electronic Rydberg states and for precision measurements. In this poster we will describe progress towards driving millimeter-wave transitions in ultracold Sr Rydberg atoms. We focus on millimeter-wave excitation of 5$sns$ ${}^3S_1$ Rydberg states to nearby ${}^3P_j$ states and ${}^3S_1$/${}^3D_j$ states with one and two-photon excitation respectively. A major motivation of the development of this technique is the study of vibrational wave-packet dynamics in ultralong-range Rydberg molecules. [Preview Abstract] |
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S01.00169: Many-body correlations in a one-dimensional spin chain with simplified dipole-dipole interactions Andre Cidrim, Tommaso Macri, Ana Maria Rey, Romain Bachelard We address the possibility of generating many-body quantum correlations in cold atomic ensembles scattering light. In particular, we consider an ordered 1D chain of two-level spins under the influence of a magnetic field that orients their dipole moments along the magic angle, thus simplifying the dipolar interactions solely to terms $\propto 1/r$. For the subwavelength limit where the lattice spacing $a < \lambda$, implying that dipole-dipole interactions are dominant and can induce stronger correlations, we observe an anti-ferromagnetic steady-state solution of the coherent dipole master equation. We thus analyze this state's tomography, measuring the pair-wise spin concurrence and other quantum-correlation quantifiers. We extend our analysis to a more complex system of multi-level atoms. Current experiments with atoms trapped by optical tweezers are particularly interesting platforms to implement this limit, due to the high degree of control they offer. [Preview Abstract] |
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S01.00170: Calculations of long-range three-body interactions for Li($2\,^2S$)-Li($2\,^2S$)-Li$^{+}$($1\,^{1}S$) Pei-Gen Yan, Li-Yan Tang, Zong-Chao Yan, James F Babb Using perturbation theory for energies, we evaluate the additive and nonadditive interaction coefficients $C_4$, $C_6$, $C_7$, $C_8$ and $C_9$ for the Li($2\,^2S$)-Li($2\,^2S$)-Li$^{+}$($1\,^{1}S$) system. The obtained coefficients $C_n$ are evaluated with highly accurate variationally-generated nonrelativistic wave functions in Hylleraas coordinates. The nonadditive interaction coefficients depend on the geometrical configurations of this three-body system and on the different positions of the ion for each configuration. Our calculations may be of interest for the study of three-body recombination and for constructing precise potential energy surfaces. [Preview Abstract] |
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S01.00171: New species and new techniques for molecular laser cooling experiments Jamie Shaw, Lucas Railing, Daniel McCarron The extension of laser cooling and trapping techniques to molecules promises access to new research directions from ultracold chemistry and quantum simulation to improved precision measurements. Recent progress laser cooling molecules has produced multiple diatomic species in the ultracold regime. To-date all of these laser-cooled species have an unpaired electronic spin and occupy $^{\mathrm{2}}\Sigma^{\mathrm{+}}$ ground states. Here we present a new experiment to laser-cool and trap molecules with closed electronic shells that occupy $^{\mathrm{1}}\Sigma^{\mathrm{+}}$ ground states. These molecules offer favorable properties for laser cooling including a lack of spin-rotation structure and the presence of both strong and weak optical transitions. These properties will support simplified laser-cooling schemes, increased optical forces for efficient trap loading and the ability to laser cool towards 1 $\mu $K. We project that these advances will allow the direct production of large, dense samples of ultracold molecules for studies that manipulate molecule-molecule interactions. Our results will include a new cryogenic source capable of producing bright, quasi-continuous beams of cold and slow molecules and a fluorescence detection scheme that is immune to the scattered light background that limits current sensitivities. [Preview Abstract] |
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S01.00172: Combining STIRAP and Feshbach resonances for ultracold molecule creation Phillip Price, Susanne Yelin We are studying methods for creating ultracold molecules from ultracold atoms. Ultracold molecules have many potential uses in quantum computation, few-body collision physics, and control of chemical reactions. We will study this problem using numerical simulations and genetic algorithms. [Preview Abstract] |
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S01.00173: Collisions between cold molecules in a superconducting magnetic trap Michael Karpov, Yair Segev, Martin Pitzer, Nitzan Akerman, Julia Narevicius, Edvardas Narevicius We observe the first directly measured collisions between cold, trapped molecules, achieved without the need of laser cooling. Following deceleration using time-dependent magnetic fields, we capture molecular oxygen in a 0.8K\textbullet kB deep superconducting magnetic trap. The density-dependent, non-exponential decay in particle number provides a clear proof of molecule-molecule collisions within the trapped ensemble. Our detection scheme allows probing the density at different locations in the trap. The spatial distribution of the trapped molecules is found to change over time, allowing to set bounds on the ratio between the elastic and inelastic scattering rates, the key parameter determining the feasibility of evaporative cooling. We further co-trap lithium atoms together with molecular oxygen and identify collisions between atoms and molecules, paving the way to studies of cold interspecies collisions in a magnetic trap. [Preview Abstract] |
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S01.00174: Long-range interaction between Rydberg atoms and alkali-metal dimers Vanessa Olaya Agudelo, Felipe Herrera, Jes\'us P\'erez-R\'ios Rydberg atoms have been proposed for non-destructive detection of cold molecules in beams and optical traps and also for sympathetic cooling of cold molecules to the ultracold regime. In order to assess the experimental feasibility of these applications, an accurate understanding of the long-range Rydberg-molecule interactions is needed. We obtain accurate $C_5$ and $C_6$ coefficients that characterize the long-range interaction between an alkali metal atom A with $n > 15$ [A $=$ Cs, Rb] and a heteronuclear alkali-metal dimer B in the electronic and vibrational ground state [B $=$ LiCs, RbCs, LiRb with $J < 3$]. Possible applications for the photoassociation of alkali-metal trimers are discussed. [Preview Abstract] |
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