Bulletin of the American Physical Society
49th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics APS Meeting
Volume 63, Number 5
Monday–Friday, May 28–June 1 2018; Ft. Lauderdale, Florida
Session T01: Poster Session III 
Hide Abstracts 
Room: Floridian Ballroom 

T01.00001: Fitting an Experimental Potential Energy Curve for the 4$^3\Pi$ Electronic State of NaCs Andrew Steely, Rachel L. Myers, R. F. Malenda, Carl Faust We present results from experimental studies of the 4$^3\Pi$ electronic state of the NaCs molecule. This electronic state is interesting in that its potential energy curve exhibits a double minimum. As a result, interference effects are observed in the resolved boundfree fluorescence spectra. The opticaloptical double resonance method was used to obtain Dopplerfree excitation spectra for the 4$^3\Pi$ state. To aid in level assignments, simulations of resolved boundfree fluorescence spectra were calculated using the BCONT program (LeRoy). Spectroscopic constants were determined to summarize data belonging to inner well, outer well, and above barrier regions of the electronic state. Several approaches are under consideration to construct a potential energy curve. The RKR and IPA methods were used to determine a pointwise potential energy curve to reproduce experimental level energies. Theoretical calculations are also underway to determine an analytic form of the potential energy curve for comparison with experimental data and results of the IPA fitting. Initial forms under investigation include a sum of two Morse potentials combined with a switching function and a Spline ExponentMorse/Long Range (SEMLR) form calculated using the betaFIT program (LeRoy). [Preview Abstract] 

T01.00002: Study of highorder effects in atomsurface interactions FangFei Wu, LiYan Tang, F. Babb James, ZongChao Yan Atomsurface interactions have attracted much attention in connection with, for example, experiments on quantum reflection and BoseEinstein condensed or ultracold atoms confined near surfaces or in atomicphotonic devices. So far, most work has been focused on the leading term of the longrange interaction coefficient C3 between an atom and a perfectly conducting surface. In this work, using existing dielectric response functions of realistic materials, the highorder dispersion coefficients C5, C7, C9, and C11 between one of the H, He, or Li atoms and a dielectric macroscopic surface are calculated, including finite nuclear mass corrections, using Gaussian quadrature. Our results may be used to construct accurate atomsurface potential energy curves. [Preview Abstract] 

T01.00003: Electronic Transition Dipole Moment and Radiative Lifetime Calculations of Lithium Dimer IonPair States Ergin Ahmed, Aydin Sanli, Xinhua Pan, David Beecher, Phillip Arndt, Jeng Tsai, Sylvie Magnier, Marjatta Lyyra The higher lying $^{1}\Sigma_{g}^{+} $ symmetry states of lithium dimer are known to exhibit multiple minima and shoulders in their potential energy curves (PECs) due to the interactions with the Li$^{\mathrm{+}}+$Li$^{\mathrm{}}$ ionpair Coulomb potential. The ionpair character of these potential energy curves makes their lifetimes interesting because of the unusual behavior of their transition dipole moments which exhibits rapid changes in regions of internuclear distance corresponding to potential energy curve shoulders and double wells. We present here a computational study of the lifetimes of the ionpair $(n^{1}\Sigma_{g}^{+} ,n=3\sim 6)$ states of Lithium dimer$_{\mathrm{.}}$ The lifetimes are calculated using \textit{abinitio} electronic transition dipole moment functions. The calculations include the radiative contributions of all the allowed boundbound and boundfree transitions to lower electronic states. [Preview Abstract] 

T01.00004: Probing the Lymanalpha transition in antihydrogen Alexander Khramov, Robert Collister, Andrew Evans, Makoto Fujiwara, Joseph McKenna, Takamasa Momose The 1s2p transition in antihydrogen is of importance from both a fundamental and technical perspective. Fundamentally, it provides an additional avenue for antihydrogen spectroscopy including a possibility of calculating the fine structure splitting and Lamb shift measurement. From a technical standpoint, the transition may be used for laser cooling of antihydrogen atoms to achieve cold trapped samples which are needed for increased precision tests of CPT symmetry and antimatter gravitational behaviour. The ALPHA collaboration at CERN employs a pulsed laser system consisting of a 365 nm beam followed by triple harmonic generation in a KrAr cell to generate pulses which can access this transition. We report on technical upgrades to the system and discuss ongoing attempts to measure the 1s2p transition in antihydrogen. We give new results of pulsed spectroscopy experiments in the 1s2p manifold from he 2017 ALPHA run at CERN. [Preview Abstract] 

T01.00005: TimeResolved Spectroscopy to investigate the radiative lifetimes of Na$_2$ $6^1\Sigma^+_g $(8,31) Michael Saaranen, Dinesh Wagle, Burcin Bayram In recent years, there has been an increased interest in the determination of the lifetime values as a result of growing demand for accurate knowledge of the transition dipole matrix elements of alkali molecules. Here we present our experimental study of the lifetime of the $6^1\Sigma^+_g$ (8,31) electronic state of sodium dimers. In this experiment the second harmonic of a Nd:YAG laser is used to pump two pulsed dye lasers that are used to make the X$^1\Sigma^+_g$ (v=0,31) $\rightarrow$ A$^1\Sigma^+_u$ (7,30) $\rightarrow 6 ^1\Sigma^+_g$ (8,31) transition. We observed the fluorescence resulting from this molecular transition to measure its radiative properties using a SternVolmer plot. We will present results of the measurement, as well as improvements made to the measurements, and provide comparison with the recent theoretical calculations. \\ [Preview Abstract] 

T01.00006: Highprecision spectroscopy in neutral beryllium9 Eryn Cook, Alisha Vira, Emma Livernois, Carson Patterson, Will Williams We report on spectroscopic measurement progress for a variety of states in neutral beryllium9.~ Measurements include the absolute transition frequencies and hyperfine constants for the 2s2p 1P1, 2s2p 3P1, and 2s3d 1D2 states.~ Our experimental result for the absolute frequency from the ground state to the 2s2p 1P1 state is in agreement with recent theoretical predictions that include the effects of quantum electrodynamics[1].~ We also present the first hyperfine spectra for the 2s2p 1P1 and the 2s3d 1D2 states. [1]Puchalski et al. PRA 87, 030502(R) (2013) [Preview Abstract] 

T01.00007: Interference between two resonant transitions with distinct initial and final states connected by radiative decay Eric A. Hessels, Marko Horbatsch, Alain Marsman The resonant line shape from driving a transition between two states, $ {\rm a} \rangle$ and $ {\rm b} \rangle$, can be distorted due to a quantummechanical interference effect involving a resonance between two different states, $ {\rm c} \rangle$ and $ {\rm d} \rangle$, if $ {\rm c} \rangle$ has a decay path to $ {\rm a} \rangle$ and $ {\rm d} \rangle$ has a decay path to $ {\rm b} \rangle$. This interference can cause a shift of the measured resonance, despite the fact that the two resonances do not have a common initial or final state. As an example, we demonstrate that such a shift affects measurements of the atomic hydrogen $\textrm{2S}_{1/2}$to$\textrm{2P}_{1/2}$ Lambshift transition due to $\textrm{3S}$to$\textrm{3P}$ transitions if the $\rm 3S_{1/2} $ state has some initial population. Link: https://doi.org/10.1103/PhysRevA.96.062111 [Preview Abstract] 

T01.00008: Strong Quantum Level Dependence of Na$_{\mathrm{2}}$ (4$^{\mathrm{1}}\Sigma_{\mathrm{g}}^{\mathrm{+}})$ Lifetimes. Nadeepa Jayasundara, Lutz Huwel, Seth Ashman, Emma Burgess Radiative lifetimes of Na$_{\mathrm{2\thinspace }}$rovibrational levels of the 4$\Sigma_{\mathrm{g}}^{\mathrm{+}}$ shelf state have been calculated in a continuation of our previous work [R. Anunciado \textit{et al.}, J. Chem. Phys. \textbf{145}, 174306 (2016)] to investigate the importance of boundfree transitions for radiative lifetimes. The lifetime calculations are performed for selected vibrational levels from 0 to 75 and rotational levels, J$=$1, 20, 40, 60, and 80 and for rotational levels from 0 to 90 in vibrational levels v $=$ 49, 50 and 51. We find that radiative lifetimes vary significantly with vibrational level, particularly around the shelf. In addition, we observe a strong, unusual, oscillatory radiative lifetime dependence on rotational quantum number. Another aspect we want to emphasize is the significance of including the boundfree transitions into the calculation which reduces the lifetime noticeably compared to the results of recent work that did not include this channel [A. Sanli \textit{et al}., J. Chem. Phys. \textbf{143}, 104304 (2015)]. The lifetimes of individual rovibrational levels of the 4$^{\mathrm{1}}\Sigma_{\mathrm{g}}^{\mathrm{+}}$ shelf state were calculated using the LEVEL 8.2 and BCONT programs by Robert Le Roy, the latter in a version modified by Brett McGeehan. [Preview Abstract] 

T01.00009: Measurement of the ratio of the 6P$_{\mathrm{j}}\to $ 7S $_{\mathrm{\raise.5ex\hbox{$\scriptstyle 1$}\kern.1em/ \kern.15em\lower.25ex\hbox{$\scriptstyle 2$} }}$ matrix elements in atomic cesium Amy Damitz, George Toh, Nathan Glotzbach, Jonah Quirk, Ian C. Stevenson, J. Choi, D.S. Elliott We report progress on a measurement of the ratio of transition matrix elements of the 6P$_{\mathrm{j}}\to $ 7S $_{\mathrm{\raise.5ex\hbox{$\scriptstyle 1$}\kern.1em/ \kern.15em\lower.25ex\hbox{$\scriptstyle 2$} \thinspace }}$ transition in atomic cesium. We use a 1.47 um diode laser and a Ti: Sapphire laser at 850 nm to drive the two photon 6S $\to $ 7S transition. We measure the ratio of the polarizationdependent intensities of the transition by changing the polarization of the diode laser. Since the 6S$\to $6P matrix elements are well known, the ratio of the 6P$_{\mathrm{j}}\to $ 7S $_{\mathrm{\raise.5ex\hbox{$\scriptstyle 1$}\kern.1em/ \kern.15em\lower.25ex\hbox{$\scriptstyle 2$} \thinspace }}$ matrix elements can be precisely determined. Combined with our recent measurement of the cesium 7S lifetime, a new measurement of this ratio allows us to determine the 6P$_{\mathrm{j}}\to $7S $_{\mathrm{\raise.5ex\hbox{$\scriptstyle 1$}\kern.1em/ \kern.15em\lower.25ex\hbox{$\scriptstyle 2$} \thinspace }}$ matrix elements. [Preview Abstract] 

T01.00010: Measurement of the Land\'e gfactor ratio of Rb87 and Rb85 Dominic Fuentes, Aracely Cobos, Jason Mora, Derek Jackson Kimball We report on a measurement of the ratio of the Rb87 and Rb85 Land\'e gfactors, $g_F(87)/g_F(85)$, based on the data from the experiment of Jackson Kimball et al., Phys. Rev. D {\textbf{96}}, 075004 (2017). The experiment simultaneously measured the spinprecession frequencies of overlapping ensembles of Rb87 and Rb85 atoms contained within an evacuated, antirelaxationcoated vapor cell. The accuracy of this measurement of $g_F(87)/g_F(85)$ exceeds that of previous measurements by over an orderofmagnitude. [Preview Abstract] 

T01.00011: Nonstatistical Branching Ratios in the Photoionization of SpinOrbit Doublets Far Above Threshold David Keating, Steven Manson, Pranawa Deshmukh Relativistic interactions are very important contributors to atomic properties. Of particular interest is the alterations made to the wave functions, i.e., the dynamics. These dynamical changes can greatly affect the photoionization cross section of heavy (high Z) atoms. To explore the extent of these dynamic effects a theoretical study of the photoionization cross section branching ratios of various spinorbit split subshells in various atoms have been performed using the relativistic random phase approximation (RRPA) methodology [1]. In the absence of relativistic effects, the branching ratios of the spinorbit split subshells should be the respective statistical ratio. Interchannel coupling can obscure these dynamic effects by affecting each of the spinorbit doublet subshells differently. Therefore, it is also necessary to perform calculations without coupling included. This is possible thanks to the RRPA model being able to calculate truncated cross sections. Comparisons are presented between calculations with and without various levels of interchannel coupling. The results show significant deviations from the statistical ratio even very far above threshold. [1] W. R. Johnson and C. D. Lin, Phys. Rev. A 20, 964 (1979). [Preview Abstract] 

T01.00012: Photoionization and Structure of the Superheavy Atom Cn (Z$=$\textbf{112)} A. K. Razavi, D. A. Keating, S. T. Manson, P. C. Deshmukh Calculations of the structure and photoionization of the closedshell superheavy Copernicium (Cn) atom have been performed using DiracFock (DF) and relativisticrandomphase approximation (RRPA) methods. Although Cn is Hglike, the ordering of the outer and nearouter subshells is rather peculiar owing to the strength of relativistic interactions at such high Z, e.g, the valence subshell is 6d$_{\mathrm{3/2\thinspace }}$and the 5f thresholds are found to lie between 6p$_{\mathrm{3/2}}$ and 6p$_{\mathrm{1/2}}$. Specifically, the ordering of the levels is hydrogenic from the 1s up to the 6s subshell. But interlopers are found between the levels of spinorbit doublets; the ordering of the outer subshells is found to be 6p$_{\mathrm{1/2}}$, 5f$_{\mathrm{5/2}}$, 5f$_{\mathrm{7/2}}$, 6p$_{\mathrm{3/2}}$, 6d$_{\mathrm{3/2}}$, 7s, 6d$_{\mathrm{3/2}}$. The binding energies of last three subshells are quite close to each other, but this result confirms a previous calculation [1]. Photoionization cross sections and angular distributions have been obtained for each subshell from threshold to about 1,400 eV and the results show that interchannel coupling dominates the photoionization process over much of the energy region. [1] J. Li \textit{et al}, Science in China: Ser. GPhys. Mech. Astr. \textbf{50}, 707 (2007). [Preview Abstract] 

T01.00013: Nondipole effects in the vicinity of coreexcited dipole and nondipole resonances at low photon energy: experiment and theory B. Kraessig, E. P. Kanter, S. H. Southworth, R. Wehlitz, V. K. Dolmatov, S. T. Manson Nearly two decades ago, calculation predicted that the firstorder nondipole photoelectron angular distribution parameters for the Ne 2p cross section show significant variation in the vicinity of both the nondipole 2s$\to $3d resonance, as well as near the dipole 2s$\to $4p resonances [1]. In order to test the accuracy of these theoretical predictions, measurements of the firstorder nondipole parameters have been performed. The comparison shows quite good agreement between theory and experiment and theory convoluted with the experimental width for the structure of the of the nondipole parameters in the neighborhoods of the resonances. However, there is some experimental difficulty ascertaining the background, nonresonant values of the nondipole parameters. This problem is still being investigated. The physics of why the parameters vary at both nondipole and dipole resonances will be discussed. [1] V. K. Dolmatov and S. T. Manson, Phys. Rev. Lett. \textbf{83}, 939 (1999). [Preview Abstract] 

T01.00014: THE IRON PROJECT \& Opacity Project: Photoionization of iron ions for Opacities and collisional excitations of P III W. Eissner, L. Zhao, R. Naghma, S. Nahar, A. Pradhan Fe~XVIII is the 2nd most abundant iron ion and probably the most contributing ion to opacity near the boundary between radiative and convection zones in the sun. The current poor agreement of the higher opacity from the 3D astrophysical model as well as and measurement at Zpinch with the predicted opacity is considered to be due to lower estimation in photoionization cross sections ($\sigma_{PI}$) of Fe XVII  XIX in the existing data. In order to obtain high accuracy $\sigma_{PI}$ with high energy resonant features, a largescale computation has been started for $\sigma_{PI}$ of Fe!XVIII in the relativistic BreitPauli Rmatrix (BPRM) method and using a large wavefunction expansion. Work is in progress to resolve all the computational challenges and preliminary results will be presented. Collision strengths for P III is also under investigation using BPRM method and a wavefunction expansion of 18 levels as the lines of this basic element of life have been detected recently. Features in collision strengths and selected line ratios for low lying levels for diagnostics of plasmas obtained from preliminary results will be presented. [Preview Abstract] 

T01.00015: Time delay in photoionization from confined atoms: A contrasting study of hard Vs smooth jellum model potential. Hari Varma Ravi, Subhashish Saha, Afsal Thuppilakkadan, Jobin Jose In recent years, time delay studies have gained prominence in the photoionization studies of atomic systems [1]. Phtoionization from the confined systems has gained wide interest due to the confinement induced modifications in the structure and dynamics [2]. A number of works related to the photoionization time delay from atoms confined byChas been reported.Conventionally annular square well potential (ASW) has been used to simulate the confinement environment. However, this model has unrealistic discontinuity at the shell boundaries. Here we explore the possibility of jellium model potential, termed as Gaussian annular square well potential (GASW), to investigate cross section, phase shift and time delay in the photoionization of confined H and Ar [3, 4]. We provide a comparison of the numerical and analytical results of the photoionization dynamics obtained from these two models. \textbf{References }[1] Pazourek et al. 2015 Rev.mod.phy. 87 765 [2] P. C. Deshmukh et al. 2014 Phys. Rev. A 89 053424 [3] AnhThu Le et al. 2009 Phys. Rev. A 80 013401 [4] M. J. Puska et al. 1993 Phys. Rev. A 47 1181 [Preview Abstract] 

T01.00016: A simple algorithm for Velocity Map Imaging systems Geoffrey Harrison, John Vaughan, Brock Hidle, Guillaume Marc Laurent 

T01.00017: Abstract Withdrawn Interatomic Coulombic decay (ICD) in HeF$^{}$ after absorption of a high energy Xray or XUV photon is investigated. In this process, the high energy photon ionizes HeF$^{}$, transforming the He$(1\mathrm{s}^2)$ state into He$^+(n=2)$ plus an escaping photoelectron, at which point the molecule begins to implode. As the molecule begins to implode, the loosely bound electron of the F$^{}$ anion can deexcite the electron in He$^{+}$, whereby the energy released causes the single or double ionization of F$^{}$ and leads to one or two ejected ICD electrons. We perform highlevel {\it ab initio} calculations for the different molecular states involved in this ICD process, and for the ICD decay rates, using the Rmatrix method as implemented by the UKRmol suite for diatomic molecules. With the calculated wave functions we will be able to determine the kinetic energy distribution of the atomic fragments, which is how such an ICD process would be identified experimentally. 

T01.00018: Phaseamplitude formalism for shape resonances in singlechannel scattering. Accurate computation of ultralong tunneling lifetimes I. Simbotin, D. Shu, R. Cote We formulate a novel approach for computing phase shifts and resonance widths for the case of a potential barrier separating two classically allowed regions. Specifically, we extend the phaseamplitude framework pioneered by Milne such that it becomes possible to compute resonance widths (lifetimes) without any restriction; indeed, no matter how narrow a resonance is, we can compute its width accurately and easily. The success of our new method is ensured by two key ingredients; namely, we establish formal relationships between different solutions of the envelope equation and also for their corresponding phase functions, and we devise an optimization procedure for finding the smooth envelope inside each of the classically allowed region. We also make a connection with the Jost function formalism, which allows us to perform a strong test for the selfconsistency and accuracy of our new approach. [Preview Abstract] 

T01.00019: Integral representation for scattering phase shifts via the phaseamplitude approach D. Shu, I. Simbotin, R. Cote We obtain a novel integral representation for scattering phase shifts, which is based on a modified version of Milne's phaseamplitude approach [W.~E.~Milne, Phys.~Rev.~\textbf{35}, 863 (1930)]. We replace Milne's nonlinear differential equation for the amplitude function $y$ with an equivalent linear equation for the envelope $\rho=y^2$, which renders our integral representation highly amenable to numerical implementations. The phase shift is obtained directly from Milne's phase function, which is computed as an integral involving the envelope function; the latter is found as the optimal solution of the envelope equation. We illustrate the advantages of the new representation with two scattering potentials. The integral representation presented in this work is fully general and it can be used for any type of scattering potential, including the Coulomb potential. [Preview Abstract] 

T01.00020: Rate constants for the formation of SiO and CS by radiative association Robert Forrey, James Babb, Phillip Stancil, Brendan McLaughlin Rate constants for the formation of SiO and CS by radiative association are calculated using accurate molecular data. The rate constants include both direct and indirect formation processes. The indirect processes (inverse rotational and electronic predissociation) are evaluated for conditions of local thermodynamic equilibrium (LTE) and also in the nonLTE limit of zero radiation temperature and atomic density. Phenomenological rate constants for SiO and CS formation in realistic astrophysical environments are expected to lie inbetween these limiting cases. An analytic formula is used to fit the rate constants for convenient use in astrophysical applications. [Preview Abstract] 

T01.00021: Cross dimensional relaxation in Lithium7 and Rubidium87 mixtures in spherical quadruple trap Fang Fang, Shun Wu, Aaron Smull, Josh Isaacs, Dan StamperKurn We report measurements of interspecies interaction strength between Lithium7 and Rubidium87, both are spin polarized in \textbar F$=$1, m $=$ 1\textgreater state in a magnetic spherical quadrupole trap. Measurements of equilibration rates for Li7 in Rb87 reservoir undergoing crossdimensional relaxation are done in three different trapping strengths. To relate the experimentally measured relaxation times to interspecies interaction strength, we perform Monte Carlo simulation assuming an energy independent isotropic scattering cross section, called "thermalization relaxation cross section", using the experimental parameters. In addition, a cross dimensional relaxation measurement is done on single bosonic species Rb87. The measured relaxation time matches the Monte Carlo simulated value using the theoretically predicted differential cross section. In the end, we will present our progress towards a new apparatus for Li7 and Rb87$_{\mathrm{\thinspace }}$ultracold molecule. [Preview Abstract] 

T01.00022: Collisional Processes in AlkaliMethane Gas Mixtures for Alkali Laser Development Alina Gearba, Philip Rich, Lucy Zimmerman, Jeremiah Wells, Jared Wesemann, Brian Patterson, Randy Knize, Jerry Sell, Stephen Spicklemire A diode pumped alkali laser is a new class of optically pumped lasers whose active medium is an alkali vapor such as potassium, rubidium or cesium. An alkali vapor laser has the capability to produce highly coherent beams in a very efficient manner, and the possibility of scaling to high powers makes these lasers of interest in a variety of applications. The operation of an alkali laser relies on efficient excitation transfer between finestructure levels of the alkali in the presence of a buffer gas. Quenching from these levels is also important as this causes unwanted heating in the laser medium which leads to a reduction in laser efficiency. We will present new precision measurements of the mixing and quenching cross sections for Rb(5$P)$ and Cs(6$P)$ in the presence of methane buffer gas. These results represent a significant increase in precision compared to previous work, and resolve a discrepancy in previous quenching measurements. [Preview Abstract] 

T01.00023: Freefree experiments: dressedatom effects during electron excitation C.M. Weaver, B.N. Kim, N.L.S. Martin, B.A. deHarak The absorption or emission of radiation during the collision of charged particles with atoms and molecules is investigated in freefree experiments. Recently the first experimental observation of dressedatom effects has been reported.\footnote{Y. Morimoto, R. Kanya, and K. Yamanouchi, Phys.\ Rev.\ Lett.\ {\bf 115}, 123201 (2015)} An estimate of the dressing of the target by the radiation's electric field may be made in terms of the electric dipole polarizability of the target. The effects (seen in Xe) were extremely difficult to measure because they occur at very small scattering angles, necessitating extraordinary efforts to eliminate the unscattered electron beam. We are investigating a way round this difficulty: freefree processes during electronimpact excitation. We observe the absorption or emission of a photon by the inelasticallyscattered electron which has lost the excited state energy during the collision; thus there is no spurious signal at small angles from the electron beam. Suitable targets are Ar and He; both have excitedstate dipole polarizabilities 10 times those of the Xe ground state. Dressed atom effects are therefore expected to occur at larger scattering angles than those required for xenon. [Preview Abstract] 

T01.00024: Comprehensive outofplane ($e,2e$) measurements and calculations on He autoionizing levels B.N. Kim, C.M. Weaver, N.L.S. Martin, B.A. deHarak, O. Zatsarinny, K. Bartschat Outofscatteringplane $(e,2e)$ measurements and calculations are reported for the three singlet helium $2\ell2\ell'$ auto\ionizing levels, with 80, 100, 120, 150, and 488 eV incidentelectron energies, and scattering angles 60$^\circ$, 50.8$^\circ$, 45$^\circ$, 39.2$^\circ$, and 20.5$^\circ$, respectively. The kinematics are the same in all cases: the momentum transfer is $K=2.1$~a.u., and ejected electrons are detected in a plane that contains the momentum transfer direction and is perpendicular to the scattering plane. The results are presented as $(e,2e)$ angular distributions energyintegrated over each level. They are compared with fully non\perturbative \hbox{$B$spline} \hbox{$R$matrix} and hybrid secondorder distortedwave + \hbox{$R$matrix} calculations. [Preview Abstract] 

T01.00025: New types of trilobitelike states in hydrogen atoms and negative ions Matthew Eiles, Chris Greene In recent years longrange Rydberg molecules, known loosely as ``trilobite" molecules, have become a vibrant research field. We have explored theoretically some variations on the concept of a trilobite molecule. We propose a method to use static field pulses to coherently manipulate a hydrogen Rydberg atom into the same superposition of Rydberg states that composes the trilobite wave function, thus forming a type of chemical bond with a single atom. Optimal control theory and a machine learning algorithm are used to design the appropriate pulse sequences to achieve this. We also show how an analogue of a Rydberg molecule can form in a system composed of a hydrogen negative ion and a nearby neutral atom. The electronic wave function in a doubly excited resonance state in the ``dipole" series of H extends over a huge spatial volume, similar to a Rydberg wave function. The same Fermi pseudopotential which describes Rydberg molecules leads in this case to shortlived anionic quasimolecular states, and also could provide a pathway to excite both symmetryforbidden and very narrow states of H through the state mixing induced by the perturber. [Preview Abstract] 

T01.00026: Computation of Electron Impact Ionization Cross sections of Iron Hydrogen Clusters  Relevance in Fusion Plasmas Umang Patel, K N Joshipura Plasmawall interaction (PWI) is one of the key issues in nuclear fusion research. In nuclear fusion devices, such as the JET tokamak or the ITER, firstwall materials will be directly exposed to plasma components. Erosion of firstwall materials is a consequence of the impact of hydrogen and its isotopes as main constituents of the hot plasma. Besides the formation of gasphase atomic species in various charge states, di and polyatomic molecular species are expected to be formed via PWI processes. These compounds may profoundly disturb the fusion plasma, may lead to unfavorable redeposition of materials and composites in other areas of the vessel. Interaction between atoms, molecules as well transport of impurities are of interest for modelling of fusion plasma. $Q_{ion}$ by electron impact are such process also important in low temperature plasma processing, astrophysics etc. We reported electron impact $Q_{ion\thinspace }$for iron hydrogen clusters, FeH$_{\mathrm{n}}$ (n $=$ 1 to 10) from ionization threshold to 2000eV. A semi empirical approach called Complex Scattering Potential  Ionization Contribution (CSP\textit{ic}) has been employed for the reported calculation$^{\mathrm{1}}$. In context of fusion relevant species $Q_{ion}$ were reported for beryllium and its hydrides, tungsten and its oxides and cluster of berylliumtungsten by Huber \textit{et al}$^{\mathrm{2}}$. Iron hydrogen clusters are another such species whose $Q_{ion}$ were calculated$^{\mathrm{2}}$ through DM and BEB formalisms, same has been compared with present calculations. $^{\mathrm{1}}$U. R. Patel \textit{et al}, J. Chem. Phys, \textbf{140} (2014) 44302 $^{\mathrm{2}}$S. E. Huber \textit{et al}, Eur. Phys. J. D. 70 (2016) 182 [Preview Abstract] 

T01.00027: Electron Loss CrossSections for Low Energy ProtonLithium Collisions Paul Oxley We present measurements of the electron loss crosssection for collisions between protons and lithium atoms in the energy range 0.75  4 keV. In this energy range the contribution from ionization is negligible and our results are effectively a measure of the charge transfer crosssection. Our measured crosssections are approximately 70{\%} higher than previous measurements, which used a different experimental technique. To investigate possible reasons for the discrepancy we provide a detailed description of our experimental apparatus and method, along with our results from experiments using helium and neon ions in place of protons. A brief description of the technique used in the prior work is also given, and possible reasons for the discrepancy between our results are highlighted. [Preview Abstract] 

T01.00028: Mutual neutralization of H$^$ with H$^+$ and H$_2^+$ Marjan Khamesian, Michael Sahlin, Patrik Hedvall, Ann E. Orel, {\AA}sa Larson We have previously studied the low energy mutual neutralization reaction in collisions of H$^+$ and H$^$ using an ab initio molecular closecoupling approach. The reaction is driven by nonadiabatic couplings between the ionpair state and the $n=2$ and $n=3$ covalent states at large internuclear distances. In present work we have calculated all states of $^1\Sigma_g^+$, $^1\Pi_g$, $^1\Sigma_u^+$ and $^1\Pi_u$ symmetries associated with the limits $n\leq4$ including the ionpair states. We have computed adiabatic potential energy curves, nonadiabatic couplings, as well as the rotational couplings between the $\Sigma$ and $\Pi$ states. The goal is to perform a detailed study and investigate the importance of the higher lying states, rotational couplings as well as nonzero asymptotic nonadiabatic couplings. These effects have previously not been considered. To perform an ab initio study of mutual neutralization in collisions of H$^$ with H$_2^+$ is a challenge. The multidimensional potential energy surfaces as well as nonadiabatic couplings for many excited electronic states have to accurately be computed. We perform full configuration interaction calculations of the states to identify the important avoided crossings/conical intersections driving the reaction. [Preview Abstract] 

T01.00029: Exploring IonAtom Collisions with EIT Enhanced Doppler Velocimetry Joseph Yadiel CorderoMercado, Jacob Johansen, ShihKuang Tung, Brian Odom As part of the growing effort to understand ultracold reactions we have developed a new technique, EIT Enhanced Doppler Velocimetry (EEDV). With this technique we intend to make single particle, time resolved, ultracold chemical reaction rate measurements. This is achieved by monitoring changes in the secular frequency of an ion crystal as it reacts with a single known species. The basis of EEDV is to utilize the narrow linewidths obtained from EIT to obtain a steeper slope on our fluorescence profile. On top of this, we implement a feedback mechanism by carefully choosing the laser frequencies in order to keep the amplitude of our oscillations steady, increasing our signal. With EEDV and a collection efficiency of 4\% we can reach a Fourierlimited time resolution of $\sim$ 1 ms. With our numerical calculations we predict a mass resolution of 8 amu in our trap. With the precision afforded by this technique we will be able to probe ionneutral atom reactions; state to state quantum chemistry; and chemistry in the very low density regime, analogous to conditions in the interstellar medium. [Preview Abstract] 

T01.00030: DSMC simulations of leading edge flatplate boundary layer flows at high Mach number Dr. Sahadev Pradhan The flow over a 2D leadingedge flat plate is studied at Mach number \textit{Ma }$= (U_{inf}/ \backslash $\textit{sqrt\textbraceleft k}$_{B}T_{inf}$\textit{/ m\textbraceright ) }in the range \textit{\textless Ma \textless 10}, and at Reynolds number number \textit{Re }$= (L_{T} U_{inf}$\textit{ rho}$_{inf\thinspace }$\textit{)/ mu}$_{inf\thinspace }$ equal to 10$^{\mathrm{\thinspace \thinspace }}$using twodimensional (2D) direct simulation Monte Carlo (DSMC) simulations to understand the flow phenomena of the leadingedge flat plate boundary layer at high Mach number. Here, $L_{T}$is the characteristic dimension, $U_{inf}$and $T_{inf}$are the free stream velocity and temperature, \textit{rho}$_{inf}$ is the free stream density, $m$is the molecular mass, \textit{mu}$_{inf\thinspace }$is the molecular viscosity based on the free stream temperature $T_{inf},$and $k_{B}$is the Boltzmann constant. The variation of streamwise velocity, temperature, numberdensity, and mean free path along the wall normal direction away from the plate surface is studied. The qualitative nature of the streamwise velocity at high Mach number is similar to those in the incompressible limit (parabolic profile). However, there are important differences. The amplitudes of the streamwise velocity increase as the Mach number increases and turned into a more flatter profile near the wall. There is significant velocity and temperature slip ((Pradhan and Kumaran, J. Fluid Mech2011); (Kumaran and Pradhan, J. Fluid Mech2014)) at the surface of the plate, and the slip increases as the Mach number is increased. It is interesting to note that for the highest Mach numbers considered here, the streamwise velocity at the wall exceeds the sound speed, and the flow is supersonic throughout the flow domain. [Preview Abstract] 

T01.00031: Vortices for Ps formation in positronhydrogen collisions in the Ore gap S. J. Ward, Albandari W. Alrowaily$^+$, P. Van Reeth Using the inverse Kohn variational method, we determine the differential cross section (DCS) for Ps formation in positronhydrogen collisions in the Ore gap. There are two deep minima in the DCS in this energy range. At the minima, the nodal lines of the real and imaginary parts of the Psformation scattering amplitude intersect which means that the amplitude is zero. Corresponding to the zeros in the Psformation scattering amplitude there are vortices in the velocity field that is associated with this amplitude. The velocity field rotates about each zero, but in opposite directions. The magnitude of the circulation [1] for the first and second zeros is $2\pi/M$ and $2\pi/M$, respectively, where $M$ is the mass of the outgoing Ps. \vskip 0.2truecm \noindent $^+$Home Institution: Princess Nourah bint Abdulrahman University \vskip 0.2truecm \noindent S.J.W. acknowledges support from NSF under Grant No.~PHYS1707792. \vskip 0.2truecm \noindent Computational resources were provided by UNT's High Performance Computing Services. \vskip 0.2truecm \noindent [1.] Iwo BialynickiBirula, Zofia BialynickaBirula, and Cezary \'Sliwa, Phys.~Rev.~A {\bf 61}, 032110 (2000). [Preview Abstract] 

T01.00032: Resonance scattering of positronium by N$_2$ Robyn Wilde, Ilya Fabrikant Since the discovery [1] of the similarity between electron and positronium (Ps) scattering by atoms and molecules, much theoretical effort has been directed to explain this intriguing observation. A particularly interesting phenomenon is the presence of a resonance in Ps scattering by nitrogen molecules [2] which looks similar to the $\Pi_g$ resonance in electron scattering by the same target if cross sections for both processes are plotted as functions of the projectile velocity. For correct treatment of Psmolecule scattering incorporation of the exchange interaction and shortrange correlations is of a paramount importance. In the present work we have used a freeelectrongas model to describe these interactions in collisions of Ps with the N$_2$ molecule. The results agree reasonably well with the experiment, but the position of the resonance is somewhat shifted towards lower energies, probably due to the fixednuclei approximation employed in the calculations. $^1$ S. J. Brawley {\it et al.}, Science {\bf 330}, 789 (2010). $^2$ M. Shipman {\it et al.}, Phys. Rev. A {\bf 95}, 032704 (2017). [Preview Abstract] 

T01.00033: A semiclassical approach for solving the timedependent Schr\"{o}dinger equation in inhomogeneous electromagnetic fields Jianxiong Li, Uwe Thumm To solve Schr\"{o}dinger's equation in spatially inhomogeneous electromagnetic fields, we propose a semiclassical approach employing timedependent WKB theory. This approach offers a fast and universal method to study electron dynamics in induced plasmonic fields near nanoparticles and nanostructures [1,2]. We scrutinize this method in first numerical applications to timeresolved photoemission spectroscopy from atoms and nanoparticles. [1] J. Li, E. Saydanzad, and U. Thumm, Phys. Rev. A \textbf{95}, 043423 (2017). [2] M. J. Ambrosio and U. Thumm, Phys. Rev. A \textbf{96}, 051403 (2017). [Preview Abstract] 

T01.00034: Ab Initio Simulation of Photoinduced Ring Currents in Benzene Tennesse Joyce, Agnieszka JaronBecker A circularly polarized femtosecond laser can induce ring currents within a single molecule on the order of microamps that are expected to remain coherent for several picoseconds. Photoinduced ring currents have not yet been observed experimentally, and most theoretical studies have assumed weak laser intensity—below about $10^{12}$ W/cm$^2$—which limits the strength of the induced current. To accurately model ring currents in benzene generated by highintensity femtosecond laser pulses, we have used TimeDependent Density Functional Theory, a direct ab initio method for molecular calculations. Our results indicate that ionization plays a larger role than previously expected at high intensities, because of a Resonance Enhanced Multiphoton Ionization (REMPI) process. [Preview Abstract] 

T01.00035: Multi photon ionization of stateprepared Li atoms in ultrashort laser pulses. Nishshanka Aruma Handi DeSilva, Bishnu P. Acharya, K.L. Romans, Sachin Sharma, Daniel Fischer In the last 20 to 30 years, highly controllable, extremely short and intense optical laser pulses became available. Pulses can reach durations close to the singlecycle limit at electric field strengths exceeding atomic Coulomb fields by many orders of magnitude. In conjunction with cold target recoil ion momentum spectroscopy (COLTRIMS), new and before inconceivable possibilities to study atomic fewparticle dynamics became accessible. Earlier experiments focused on the ionization of noble gases and molecular targets from ground state. Here we report on an experiment using a lithium target which can be prepared in excited or polarized states before ionizing it. This allows to obtain substantial additional insights. By modifying the mutual overlap of singleelectron wave functions in the target, the influence of electronic correlations, which are generally very challenging to describe accurately, can be tested and disentangled directly. Moreover, having a single active electron in an excited eigenstate allows one to test angular momentum and orientation effects for welldefined initial and final configurations. This will enable to address the fundamental questions, how electronic correlation and polarization influence the shorttime dynamics in strong fields. [Preview Abstract] 

T01.00036: Comparing the performance of timedependentSchr\"odingerequation solvers for the 800nm, oneelectronatom, strongfield problem B.D. Esry, Yujun Wang, D. Ursrey, Henrik R. Larsson, D.J. Tannor, Nicolas Douguet, Klaus Bartschat, A.N. GrumGrzhimailo, Bruno Schulz, Alejandro Saenz, L Marder, D.M. Reich, C.P. Koch, A. Scrinzi, F. Morales, T. Bredtmann, H.G. Muller, S. Patchkovskii, Xiao Wang, F. Robicheaux, V. Mosert, D. Bauer, X.M. Tong, J. Svensmark Numerical solutions of the strongfield timedependent Schr\"odinger equation (TDSE) have been pursued for decades, leading many to consider it a ``solved'' problem. While it is ``solved'' in the sense that many methods do exist for its solution, their relative performance ranges over orders of magnitude. Moreover, these methods are still so resource intensive that they are rarely used to carry out a full, quantitative comparison with experiment. An accurate and efficient TDSE solver is thus critical, and the first step towards improving the stateoftheart is identifying it. To this end, we will present a comparison of several common methods, thereby providing an informed starting point for future efforts to develop TDSE solvers as well as a yardstick to measure them against. [Preview Abstract] 

T01.00037: Role of central frequency in pulse shapes used in simulations of Time Dependent Schr\"{o}dinger Equation Joel Venzke, Tennesse Joyce, Zetong Xue, Cory Goldsmith, Ran Reiff, Agnieszka JaronBecker, Andreas Becker When performing numerical simulations of lasermatter interaction for pulses of few cycles, it is known that the electric field should be defined via the derivative of a given vector potential to guarantee that both field and potential vanish at the end of the pulse. It can be shown that in this case the central frequencies of the electric field and the vector potential do not agree. The frequency shift increases as the number of cycles in the pulse decreases. Examples of the effect will be shown for various ultrafast strong field processes. [Preview Abstract] 

T01.00038: Bulk and surface contributions to highharmonic generation in solids Francisco Navarrete, Uwe Thumm While the generation of highharmonics (HH) from gaseous atoms is well understood [1], HH generation from solids is discussed theoretically for decades [2], still debated [3, 4], and scrutinized experimentally only recently [3]. We investigated the fieldstrength and carrierenvelopephase dependence of HH generation by the interaction of intense midinfrared fewcycle laser pulses with Au, SiO$_{\mathrm{2}}$, and ZnO, for which experimental data exists [3]. We numerically solved the timedependent Schr\"{o}dinger equation in one spatial dimension to analyze bulk and surface effects within a basissetexpansion approach that allows us to (i) perform many steps of the calculation analytically and (ii) tune bandstructure parameters of the solid to the valenceelectronic structure of the solids. [1] A.T. Le, \textit{et al.}, Phys. Rev. A \textbf{80}, 013401 (2009). [2] L. Plaja and L. RosoFranco, \textit{Phys. Rev. B} \textbf{45}, 8334 (1992). [3] S. Ghimire \textit{et al}., \textit{Nat. Phys,} \textbf{7}, 138 (2011); M. Wu, \textit{et al.,} Phys. Rev. A \textbf{91}, 043839 (2015) [4] G. Vampa, \textit{et al}. \textit{Phys. Rev. Lett,} \textbf{113}, 073901 (2014). [Preview Abstract] 

T01.00039: Influence of surface plasmon polaritons on heating of gold after irradiation with ultrashort laser pulses Pavel N. Terekhin, Sebastian T. Weber, Pascal D. Ndione, Baerbel Rethfeld We present a detailed investigation of surface plasmon polaritons (SPPs) excitation and decay after irradiation of gold with ultrashort laser pulses. SPPs can be created at a defect structure of an Au surface. Our aim is to show the influence of the electrical field enhancement resulting from SPPs on heating of a metal. We achieve this goal by developing an extended twotemperature model (TTM) which takes into account the interaction of hot electrons with an additional plasmon subsystem. The developed method for calculation of materials' heating after ultrashort laser irradiation allows to study the fundamental mechanisms of laser energy absorption. It also can be used to study the morphological effects and nanostructuring for the technological applications. [Preview Abstract] 

T01.00040: Angle resolved Wigner time delay studies in the photodetachment of Br$^{\mathrm{\mathbf{}}}$\textbf{and I}$^{\mathrm{\mathbf{}}}$ S. Saha, A. Mandal, P. C. Deshmukh, A. S. Kheifets, V. K. Dolmatov, S. T. Manson Time resolved studies of atomic photoionization have become a rapidly growing research area. Recent studies of photodetachment time delay [1, 2] in negative ions has enabled us to see the effect of centrifugal barrier shape resonances on the time delay, as well as obtain the pure Wigner delay uninfluenced by the large Coulomb component and, hence, free from the CoulombLasercoupling [3]. Photoionization time delay depends on the angle between the momentum direction of the outgoing photoelectron and the laser polarization [4, 5]. In the present study we report the angle dependence of photodetachment time delay for Br$^{\mathrm{}}$ and I$^{\mathrm{\thinspace }}$in the region of the centrifugal barrier shape resonance. In particular, we study outer n$d\to \varepsilon f$ transitions for both the singly charged negative ions, Br$^{\mathrm{}}$ and I$^{\mathrm{}}$. Calculations have been performed using relativistic random phase approximation (RRPA) [6]. [1] S. Saha \textit{et al}, Bull. Am. Phys. Soc. \textbf{61}(8), 53 (2016); [2] E. Lindroth and J. M. Dahlstr\"{o}m, Phys. Rev. A \textbf{96}, 013420 (2017); [3] R. Pazourek \textit{et al}, Rev. Mod. Phys. \textbf{87}, 765 (2015); [4] J. W\"{a}tzel \textit{et al}, J. Phys. B \textbf{48}, 025602 (2015); [5] A. Mandal \textit{et al}, Phys. Rev. A\textbf{96}, 053407 (2017); [6] W. R. Johnson and C. D. Lin, Phys. Rev. A \quad \textbf{20,} 964 (1979). [Preview Abstract] 

T01.00041: Angular dependence of Photoelectrons in SpeciesRelative Time Delay S. Saha, S. Banerjee, A. Mandal, P. C. Deshmukh, A. S. Kheifets, V. K. Dolmatov, S. T. Manson Time resolved photoemission of atoms enables us to see real time quantum dynamics [1]. The relative time delay in photoionization from Ne, Ar, Kr have been measured with respect to He [2]. SpeciesRelative Time Delay (SRTD) from different atoms and its angle dependence are important for a variety of reasons. Hence this line of study is indicated in terms of understanding the correlated electron dynamics. It is also possible to measure other SRTD's such as ArKr, ArXe which can reveal some aspects of photoionization dynamics which is otherwise suppressed in the extraction of time delay from individual species by a pumpprobe experiment. In this work we present and analyze photoionization SRTD for the following combinations: HeNe, HeAr, HeKr, HeXe; NeAr, NeKr, NeXe; ArKr, ArXe; KrXe. The angle dependent SRTD are computed in DHFRRPA [35] methodology and the weighted averages are also made for the comparison with the available experimental observations. Calculations are done at different levels of truncation for understanding of the Spin Orbit Interaction Activated Interchannel Coupling (SOIAIC) effects [5] which cause large excursions of the time delay near thresholds. [1] M. Schultze \textit{et al}., Science \textbf{328}, 1658 (2010); [2] C. Palatchi \textit{et al}. J. Phys. B \textbf{47}, 245003 (2014); [3] W. R. Johnson and C. D. Lin, Phys. Rev. A\textbf{ 20,} 964 (1979); [4] A. Kheifets \textit{et al.}, Phys. Rev. A, \textbf{94}, 013423 (2016); [5] A. Mandal \textit{et al.}, Phys. Rev. A \textbf{96}, 053407 (2017). [Preview Abstract] 

T01.00042: Trajectory selective study of photoelectrons in strong fields Andrew Piper, Dietrich Kiesewetter, Jens Baekhoj, Kenneth Schafer, Pierre Agostini, Louis DiMauro The recollision of an electron photoionized by a high intensity laser pulse is commonly understood using the semiclassical model. This model explains a variety of strong field phenomena such as high harmonic generation, the production of high energy electrons and nonsequential double ionization. In the first step, the laser tunnel ionizes the atom and the released electron enters a continuum state. Then, the electron is accelerated by the light field. Finally, the electron can recollide with the parent ion. We plan to investigate the last two steps in the recollision process by modifying the first, photoionizing atoms with an XUV attosecond pulse train (APT) in the presence of a phase locked IR field. The APT will allow us to resolve the dynamics of individual trajectories, by seeding the photoionization process. This experiment will serve as a fundamental study of electron correlations in the strong field limit. We report initial measurements demonstrating the viability of this approach and the design of a novel interferometer to carry out further investigations. [Preview Abstract] 

T01.00043: Energy and angular momentum exchanges due to the postcollision interaction in a nearthreshold Auger ionization process Xiao Wang, Francis Robicheaux When the energy of an innershell photoionization is close to the threshold, the postcollision interaction (PCI) between a slow photoelectron and a fast Auger electron plays an important role in the Auger electron spectroscopy. The photoelectron can be recaptured, or shaked up/down to different bound states due to the energy and angular momentum exchanges between the photoelectron and the Auger electron. In general, numerical calculations could face difficulties when the innershell electron is excited to highly excited states where the Auger width is greater than the Rydberg spacings. We have performed calculations based on timedependent Schrodinger equations and classical trajectory Monte Carlo methods using different parameters to mimic different atomic systems. Properties of the photoelectron after PCI are studied. These results can help us better understand the correlation between the photoelectron and the Auger electron in a nearthreshold Auger ionization process. [Preview Abstract] 

T01.00044: TimeResolved TwoColor Xray Pump/ Xray Probe Photoelectron Spectroscopy A Al Haddad, A Picon, M Bucher, G Doumy, R Coffee, M Holmes, J Krzywinski, A Lutman, A Marinelli, S Moeller, T Osipov, S Pratt, D Ratner, P Walter, D Ray, L Young, S Southworth, C Bostedt Recently, Xray Free Electron Lasers proved the ability to produce two intense femtosecond xray pulses with controlled time delay and color. Combining these unique capabilities with Xray photoelectron spectroscopy (XPS), a powerful tool for extracting chemical information of a specific site by measuring the binding energy of core electrons, enables femtosecond timeresolved XPS experiments with chemical and site specificity. Such technique allows us to observe electronic and nuclear dynamics of out of equilibrium states. We will present our work on Xray pump/Xray probe XPS experiment in CO gas, where we excited a corehole on the oxygen site and probed the carbon. We observe electronic and nuclear dynamics in the first 40fs. We will further discuss our followup experiment and the future of such techniques in the light of the recent developments related to attosecond pulses at XFELs. [Preview Abstract] 

T01.00045: ABSTRACT WITHDRAWN 

T01.00046: Ultrafast Transient Polarization Spectroscopy of Electronically Excited Molecular Systems Richard Thurston, Niranjan Shivaram, Elio Champenois, Said Bakhti, Pavan Muddakrishna, Ali Belkacem, Daniel Slaughter Polarization spectroscopy has been used in the past to study dynamics in solid, liquid and gas phase systems on picosecond and femtosecond time scales. In polarization spectroscopy, two laser pulses (drive and probe) with a relative polarization of 45 degrees, interact with the medium. Due to the third order nonlinear polarization induced in the medium a signal with a polarization orthogonal to the probe is generated along the probe direction. By introducing inphase and outofphase local oscillators in conjunction with lockin amplification, the signal after a cross polarizer gives a sensitive measurement of the real and imaginary components of the medium's third order nonlinear response. Here, we discuss this method as applied to electronically excited systems and present preliminary measurements of the ultrafast electronic response of liquid nitrobenzene. We then extend this method to the study of ultrafast dynamics in gas phase polyatomic molecular systems and discuss the enhanced sensitivity of this method compared to ultrafast transient absorption spectroscopy. [Preview Abstract] 

T01.00047: Ultrafast electron diffraction imaging of isolated molecules with a high repetitionrate relativistic electron gun Daniel Slaughter, Xiaojun Wang, Kyle Wilkin, Brandon Griffin, FuHao Ji, Joshua Williams, Martin Centurion, Daniele Filippetto We report recent developments at a new facility to directly measure the molecular structure of gases with ultrafast (100 fs) pulses of electrons with relativistic energies (780 keV). We aim to measure the changes in internal structure of a molecule as it evolves on ultrafast timescales during a chemical reaction, using the High Repetitionrate Electron Scattering (HiRES) beamline at the Advanced Photoinjector Experiment (APEX) facility at LBNL. The unique capabilities of the beamline are MHz electron pulse repetition rates, allowing high electron flux and high spatial and temporal resolution. Highly coherent electrons are produced by laser and RF electron pulse shaping in space time and energy. This combination provides unprecedented capability to track molecular structural dynamics on ultrafast timescales. Details of the instrumentation and analysis will be presented with preliminary results from first experiments on gases. [Preview Abstract] 

T01.00048: Nonlinear optical response in bandgapped graphenelike materials. Hossein Z. Jooya, Hossein R. Sadeghpour Densityfunctional theory is performed to obtain the unperturbed band structure for a range of bandgap graphenelike surfaces. The interband multiphoton transitions of these systems are studies using the nonperturbative FluoquetLiouville supermatrix approach. Quasienergy band structures are used to calculate the single and multiplephoton absorption spectra. We will discuss the implications for the observed FloquetBloch states in time and angleresolved photoemission spectroscopy. [Preview Abstract] 

T01.00049: Generation of circularly polarized XUV and softxray highorder harmonics by homonuclear and heteronuclear diatomic molecules subject to bichromatic counterrotating circularly polarized intense laser fields John Heslar, Dmitry A. Telnov, ShihI Chu Recently, the studies of bright circularly polarized highharmonic beams from atoms in the soft Xray region as a source for Xray magnetic circular dichroism measurement in a tabletopscale setup have received considerable attention. Here, we address the problem with molecular targets and perform a detailed quantum study of H$_{\mathrm{2}}^{\mathrm{+}}$, CO, and N$_{\mathrm{2}}$ molecules in bichromatic counterrotating circularly polarized laser fields where we adopt wavelengths (1300 nm and 790 nm) and intensities (2x10$^{\mathrm{14}}$ W/cm$^{\mathrm{2}})$ reported in a recent experiment. Our treatment of multiphoton processes in homonuclear and heteronuclear diatomic molecules is nonperturbative and based on the timedependent density functional theory for multielectron systems. The calculated radiation spectrum contains doublets of left and right circularly polarized harmonics with highenergy photons in the XUV and soft Xray range. Our results reveal intriguing and substantially different nonlinear optical responses for homonuclear and heteronuclear diatomic molecules subject to circularly polarized intense laser fields. We study in detail the below and abovethreshold harmonic regions and analyze the ellipticity and phase of the generated harmonic peaks. [Preview Abstract] 

T01.00050: Classical oscillator model for timedependent opacity in an ultracold atom gas Jonathan Gilbert, Jacob Roberts In many ultracold gases, the absorption length of light can be made to be much smaller than the spatial dimensions of the gas. Light incident from outside the gas in such a situation would in general be strongly absorbed. For light near resonance, however, the atoms have a response time on the order of an excited state lifetime. For short enough light pulses the gas is transparent, despite being opaque in steadystate. We have developed a classical model that can quantitatively predict the dynamical response of such a gas for experimentally achievable dilute ultracold gas conditions by modeling the atoms as classical oscillators. Comparison of these model predictions to measurements can be used to quantify the importance of quantum effects. We present scaling considerations with regard to computational requirements for realistic systems. [Preview Abstract] 

T01.00051: Quantum control of spinorbit mixed quantum states in a fourlevel molecule system coupled by three lasers Jianbing Qi We study the ac Stark effect in a spinorbit mixed fourlevel molecular system coupled by three lasers. The spinorbit mixed rovibrational levels in diatomic molecules are very common. The mixed states can carry both characteristics of the singlet and triplet states depending on the degree of mixing. The spinorbit mixed states have been used as gateways to access some normally prohibited transitions in laser spectroscopy. The mixing coefficient of the mixed states varies from case to case. However, by coupling the mixed states to auxiliary quantum states with lasers, the mixing coefficient of the singlettriplet states can be modified by ac Stark effect via the Rabi frequency of the lasers and the detuning of the laser frequency. We use density matrix equations in a fourlevel molecular model to show that a mixed singlettriplet pair of rovibrational levels can be controlled to enhance the access to the target quantum states. [Preview Abstract] 

T01.00052: ABSTRACT WITHDRAWN 

T01.00053: Design and Characterization of magnetic shielding for the ARIADNE Axion Experiment Chloe Lohmeyer, Jordan Dargert, Melinda Harkness, Harry FosbinderElkins, Andrew Geraci The Axion Resonant InterAction Detection Experiment (ARIADNE) will search for the QCD axion using a new technique based on Nuclear Magnetic Resonance [1]. The axion acts as a mediator of novel spindependent forces between an unpolarized Tungsten source mass and a sample of laserpolarized 3He gas. Unlike dark matter ``haloscopes,'' by sourcing the axion locally in the lab the experiment is independent of cosmological assumptions. The project relies on a stable rotation mechanism for the source mass as well as superconducting magnetic shielding to limit ordinary magnetic noise. Testing of the thinfilm superconducting shielding to be used in the experiment and characterization of magnetic noise from the source mass sample will be reported. Progress on testing the stability of the rotary mechanism will also be discussed. [1] A.A. Geraci, H. FosbinderElkins, C. Lohmeyer, J. Dargert, M. Cunningham, M. Harkness, E. LevensonFalk, S. Mumford, A. Kapitulnik, A. Arvanitaki, I. Lee, E. Smith, E. Wiesman, J. Shortino, J.C. Long, W.M. Snow, C.Y. Liu, Y. Shin, Y.Semertzidis, Y.H. Lee (ARIADNE collaboration), arxiv: 1710.05413 [Preview Abstract] 

T01.00054: Next generation of the electron's Electric Dipole Moment using trapped ThF$^{\mathrm{+}}$ molecular ions Yan Zhou, Kia Boon Ng, Daniel Gresh, William Cairncross, Tanya Roussy, Yuval Shagam, Kevin Boyce, Lan Cheng, Jun Ye, Eric Cornell ThF$^{\mathrm{+}}$ has been chosen to replace HfF$^{\mathrm{+}}$ in the nextgeneration JILA electron's Electric Dipole Moment (eEDM) measurement, because of two major advantages: (i) the eEDMsensitive state ($^{\mathrm{3}}\Delta_{\mathrm{1}})$ is the ground state, which facilitates a long coherence time [1]; (ii) its effective electric field (35 GV/cm) is 50{\%} larger than that of HfF$^{\mathrm{+}}$, which promises a direct linear increase of the eEDM sensitivity [2]. In this poster, we present recent experimental progress towards the preparation of ThF$^{\mathrm{+}}$ in a specific eEDM sensitive state (a single m$_{\mathrm{F}}$ state of $^{\mathrm{3}}\Delta_{\mathrm{1}})$, and the efficient detection of the electron spin resonance signal by resonant enhanced multiphoton dissociation (REMPD) of molecular ions. [1] D. N. Gresh, K. C. Cossel, Y. Zhou, J. Ye, E. A. Cornell, Journal of Molecular Spectroscopy, 319 (2016), 19 [2] M. Denis, M. S. N{\o}rby, H. J. A. Jensen, A. S. P. Gomes, M. K. Nayak, S. Knecht, T. Fleig, New Journal of Physics, 17 (2015) 043005. [Preview Abstract] 

T01.00055: Optimizing Point Source Atom Interferometry for Inertial Navigation YunJhih Chen, Azure Hansen, Gregory Hoth, Eugene Ivanov, John Kitching, Elizabeth Donley To move atom interferometry from laboratories to navigational applications, we evaluate the technique of point source atom interferometry (PSI) [1]. With PSI, the Raman $\pi/2\pi\pi/2$ pulse sequence is applied to a ballistically expanding cloud of cold atoms. Because of the correlation between final position and atom velocity, a spatial sinusoidal fringe pattern arising from rotations is imprinted on the atom population at the end of the pulse sequence. By imaging the fringe pattern, the PSI technique simultaneously measures acceleration in the propagation direction of the Raman lasers and rotation in the plane perpendicular to that direction. This simple experimental geometry makes the technique promising for miniaturization. We have previously demonstrated a PSI gyroscope, which used a vacuum volume of 1 cm$^3$ [2]. We will present our ongoing work on optimizing the system.\\ [1] Dickerson \textit{et al.}, Phys. Rev. Lett., \textbf{111}, 083001 (2013)\\ [2] Hoth \textit{et al.}, Appl. Phys. Lett., \textbf{109}, 071113 (2016) [Preview Abstract] 

T01.00056: Towards atom interferometry with squeezed states Baochen Wu, Graham P. Greve, James K. Thompson We have previously demonstrated approximately 18 dB of spin squeezing in an ensemble of Rb 87 atoms using cavityenhanced collective measurements (Cox et al, PRL 116, 093602). ~We will present our recent progress towards mapping spin squeezed states onto a squeezed matterwave interferometer. [Preview Abstract] 

T01.00057: Precision mass measurements with molecular ions: resolving rotational and vibrational energy David Fink, Jordan Smith, Saeed Hamzeloui, Edmund Myers Precision measurements of the cyclotron frequency ratios H$_{3}^{+}$/HD$^{+}$ and H$_{3}^{+}$/$^{3}$He$^{+}$ have shown differences in the masses of H$_{3}^{+}$ ions due to rotational energy. From this, we have confirmed that some high J,K states of H$_{3}^{+}$ have mean lifetimes exceeding several weeks. Using the lightest H$_{3}^{+}$ ion, we have obtained lower limits on the atomic masses of the deuteron and helium3 with respect to the proton. To obtain further information on the relative masses of the proton and deuteron, we are now measuring the cyclotron frequency ratio H$_{2}^{+}$/D$^{+}$. From our measurements we can observe the vibrational decay of H$_{2}^{+}$ and identify its vibrational state. [Preview Abstract] 

T01.00058: Evaluation of a lithium magnetooptical trap as a primary pressure gauge Daniel S. Barker, Eric B. Norrgard, Julia Scherschligt, Nikolai N. Klimov, James A. Fedchak, Stephen Eckel Preparation and control of extremehighvacuum (XHV) environments, as necessary for emerging quantum technologies, has been hindered by the lack of primary pressure gauges. We present preliminary studies of pressure sensing with a lithium magnetooptical trap (MOT). The loss rate from the MOT is compared to semiclassical collision theory to extract the vacuum pressure. We develop a model of the MOT escape velocity since it represents the dominate nonstatistical error of the pressure measurement. The robustness of MOTs makes them ideal candidates for deployable sensors and we discuss our efforts to miniaturize a lithium MOT for this purpose. [Preview Abstract] 

T01.00059: Quantum Sensors and the Chu Limit for Classical Communication David Meyer, Kevin Cox, Paul Kunz The fastest classical communication rates are achieved using antennas with high sensitivity and low Qfactor, which provides the largest bandwidth. The Chu Limit establishes that the minimum Q for a classical antenna is proportional to the cube of the wavelength of the electric field and inversely proportional to the volume of the conductor. Here we investigate this limit with respect to a quantum sensor, Rydberg atoms in a thermal vapor, which has been shown to be ideally suited for measuring electric fields ranging from 100 MHz to 1 THz. We present a derivation of the Q of a Rydberg atom receiver, via direct and nondemolition measurement, which shows a more favorable scaling than comparable classical antennas of similar size, suggesting the Rydberg atom receiver could enable faster communication rates than that currently available. [Preview Abstract] 

T01.00060: A Ramseybased widefield magnetic imager using NVdiamond Patrick Scheidegger, Connor Hart, Erik Bauch, Jennifer Schloss, Matthew Turner, Ronald Walsworth We demonstrate a Ramseybased widefield magnetic imager employing a high density layer of nitrogenvacancy (NV) color centers at the surface of a diamond chip. Three extensions to standard Ramsey sensing are employed to significantly enhance the sensitivity of the imager. First, we sense in the NV center doublequantum basis \textbraceleft 1,$+$1\textbraceright to eliminate commonmode noise sources, such as crystallattice strain fields. Second, we control the diamond bath spins to extend the effective sensing time, which is typically limited by interactions with an inhomogeneous spin environment. Lastly, we deploy a doubledifferential noise cancellation scheme for effective noise rejection and mitigation of pulse errors caused by inhomogeneities of the applied MW fields. [Preview Abstract] 

T01.00061: Optimization of NVDiamond Material Properties for High Sensitivity Magnetometry Jennifer Schloss, Diana Craik, Andrew Greenspon, Xingyu Zhang, Erik Bauch, Connor Hart, Matthew Turner, Patrick Scheidegger, Evelyn Hu, Ronald Walsworth Enhancing the sensitivity of ensemblebased magnetometry using NVdiamond requires optimized diamond samples with a high density of negativelycharged NV centers, good fluorescence contrast, and long spin coherence times. Here we report a systematic study of both the conversion efficiency from nitrogen to NV and the negativetoneutral NV charge state ratio versus initial nitrogen concentration, irradiation dose, and optical excitation intensity. We present a theoretical model that describes the measured NV charge state dynamics in the presence of both green laser excitation and substitutional nitrogen defects. We correlate a range of characterization measurements, and we draw conclusions on the optimal samples for NV magnetometry, with applications to magnetic surveying, geophysics, and neuroscience. [Preview Abstract] 

T01.00062: Longitudinal relaxation time measurement for 129Xe in NMR gas cells with Rabi oscillation Rui Zhang, ZhiGuo Wang, Xiang Peng, Hong Guo NMR oscillator based on 129Xe in NMR gas cells is a good probe to test the nEDM, in which both the longitudinal and transverse relaxation times are key parameters. We present a method to measure the longitudinal and transverse relaxation times simultaneously with high speed. Because longitudinal relaxation leads to a damp of the Rabi oscillation of the 129Xe ensemble and the damping factor is a function of longitudinal relaxation time, the longitudinal relaxation time can be obtained with Rabi oscillation information. Besides, when stimulating magnetic field is removed, the 129Xe spin polarization damps with a time constant of transverse relaxation time. The method can be used to measure the relaxation times of 129Xe nuclei spins quickly. [Preview Abstract] 

T01.00063: Synchronous Spin Exchange Optically Pumped NMR Gyro Susan Sorensen, Daniel Thrasher, Josh Weber, Anna Korver, Thad Walker We discuss the leading systematic errors of a synchronous spin exchange optically pumped NMR gyro. Xe131 and Xe129 are simultaneously polarized transverse to a pulsed bias magnetic field through spin exchange collisions with polarized Rb atoms. We further discuss progress towards using our device to search for long range interactions from axionlike particles. [Preview Abstract] 

T01.00064: Higherorder harmonics for 3Dcavity microwave magnetometry with Rabi resonances. Andrei Tretiakov, Clinton Potts, John Davis, Lindsay LeBlanc Atomic systems can be used in quantum information applications as an interface between microwaves, which can couple to superconducting quantum circuits, and electromagnetic waves at optical or telecom wavelengths, which are wellsuited for transferring quantum information along optical fibers. In addition, due to long coherence times, atomic hyperfine ground states are very promising for microwave quantum memory. Strong coupling to the microwave field, essential for efficient performance, can be achieved by placing the atomic ensemble inside a 3D microwave resonator. A convenient way to measure the coupling strength is to apply a phase modulation to the microwave field and analyze the spectrum of the steadystate oscillations in the population of the hyperfine levels. Here, we go beyond the usual smallsignal approximation and experimentally show presence of higher order harmonics in this spectrum in cold $^{87}$Rb atoms. We will extend this technique to experimentally study the microwave field inside the 3D resonator and explore applications of this system. Along with numerical simulation, we study the potential of this technique for improving the precision of microwave magnetometry. [Preview Abstract] 

T01.00065: Distinguishing Information Scrambling from Decoherence in a Trapped Ion Quantum Simulator T. Schuster, K. A. Landsman, C. Figgatt, N. M. Linke, B. Yoshida, N. Y. Yao, C. Monroe The dynamics of a strongly interacting manybody system causes the scrambling of quantum information, wherein local information becomes ``hidden'' in nonlocal observables. Recently, a powerful theoretical proxy to diagnose scrambling has emerged in the form of outoftimeordered correlation functions (OTOCs). However, the direct and unambiguous experimental measurement of scrambling via such OTOCs remains an essential challenge. This challenge can be summarized as follows: for a generic interacting system, the scrambling of quantum information will cause OTOCs to decay to zero. However, both decoherence and imperfect experimental controls (e.g.~time reversal) will \emph{also} cause OTOCs to decay to zero. Inspired by the HaydenPreskill variant of the black hole information problem, we describe a quantumteleportationbased scheme which explicitly detects both the ``erroneous decay'' of OTOCs (from noise and decoherence) as well as the desired decay due to information scram bling. We present the experimental realization of this scheme on a 7qubit trapped ion quantum computer. The scrambling operation is realized via a digital 3qubit quantum gate, and teleportation fidelities of up to ~80\% are achieved enabling us to bound the true scrambling induced decay of the OTOC. [Preview Abstract] 

T01.00066: New Apparatus for a Precision Measurement of the Proton Magnetic Moment Mason Marshall, Kathryn Marable, Andra Ionescu, Geev Nahal, Gerald Gabrielse Comparisons of the properties of matter and antimatter particles comprise a precise test of the Standard Model. Specifically, the comparison of the proton and antiproton magnetic moments $\frac{\mu_p}{\mu_{\bar{p}}}$ is a stringent test of CPT invariance in the hadronic sector. In the past few years, work at the CERN Antiproton Decelerator and elsewhere has dramatically improved the precision of this comparison \footnote{J. DiSciacca et al, \textbf{Phys. Rev. Lett} 110, 130801} \footnote{C. Smorra et al, \textbf{Nature} 550, 371}. We present the design and initial commissioning results of a new apparatus for a more precise measurement of the proton and antiproton gfactors. Several improvements have been implemented over previous methods, including a cryogenic system for insitu alignment of the electric and magnetic fields; a redesigned particle trap to improve magnetic field homogeneity; and a new measurement scheme which suppresses systematic uncertainties. This apparatus will initially be used at Harvard and Northwestern for an improved measurement of the proton magnetic moment, after which it will be transferred to CERN for a direct comparison measurement with the antiproton magnetic moment. [Preview Abstract] 

T01.00067: Numerical studies of a MatterWave Open Quantum System Michael Stewart, Ludwig Krinner, Arturo Pazmino, Joonhyuk Kwon, Dominik Schneble In a recent experiment \footnote{L. Krinner, arxiv 1712.07791}, we implement a model for an open quantum system consisting of an array of WeisskopfWigner type emitters (``artificial atoms'') realized with ultracold atoms in an optical lattice geometry \footnote{I. de Vega et. al, Phys. Rev. Lett. \textbf{101}, 260404, 2008}. Each emitter can spontaneously emit matter waves, with fully tunable decay strength and excited state energy. In a recent theoretical analysis \footnote{M. Stewart et. al, Phys. Rev. A \textbf{95}, 013626, 2017}, we studied a single site coupled to a onedimensional waveguide and analyzed the transition from Markovian to nonMarkovian dynamics including the formation of a bound state. In the experiment, we found strong qualitative deviations of the data compared to the single site analytical treatment. We present numerical studies on the effect of neighboring groundstate emitters, which suggest that the observed differences can be explained in terms of resonant reabsorption of emitted matter waves, such as tunneling and diffusion. We also propose schemes for direct characterization of transport properties in the lattice. [Preview Abstract] 

T01.00068: Momentum distribution and Tan contact matrix for 1D spinor quantum gas in strong interacting limit Shah Saad Alam, Li Yang, Han Pu Using our previous work on the onebody density matrix (OBDM), we present a result for the momentum distribution for a 1D spinor quantum gas with arbitrary spin in the strongly interacting limit, and show how the momentum distribution can be used to characterize various quantum phases of the underlying effective spin Hamiltonian. Furthermore, we show how the Tan contact may be extracted from the momentum tail. Previous studies on Tan contact and the associated Tan relations focused on a few specific spinor systems, such as spinless bosons and spin1/2 fermions. We discuss our ongoing investigation of the Tan contact matrix for a general spinor system. [Preview Abstract] 

T01.00069: Probing homogeneous twodimensional Fermi gases in momentum space Lennart Sobirey, Niclas Luick, Fynn F\"{o}rger, Thomas Lompe, Henning Moritz Ultracold Fermi gases in highly anisotropic traps have recently become available as versatile tools for studying the manybody physics of strongly interacting twodimensional (2D) manybody systems. However, the available experimental probes have so far been limited by the inhomogeneous density distributions in harmonic trapping potentials, where nonlocal quantities such as the momentum distribution can only be measured as trapaverages. Here, we present the experimental realisation of a homogeneous 2D Fermi gas trapped in a box potential, which is realized by a ring shaped blue detuned beam with steep walls. We employ matter wave focussing to measure the momentum distributions of homogeneous 2D Fermi gases in the crossover from the ideal Fermi gas to the regime of strongly interacting bosonic molecules. For a noninteracting Fermi gas, we directly observe Pauli blocking in the unity occupation of momentum states. [Preview Abstract] 

T01.00070: Density Wave Instability in Bilayer Dipolar Systems in the Antiparallel Configuration B. Tanatar, E. Akaturk, S.H. Abedinpour We consider a bilayer of dipolar particles in which the polarization of dipoles is perpendicular to the planes, in the antiparallel configuration. Using accurate static structure factor $S(q)$ data from hypernettedchain and Fermi hypernettedchain calculations, respectively for an isolated layer of dipolar bosons and dipolar fermions, we construct effective screened intralayer interactions. Adopting the randomphase approximation for interlayer interactions, we investigate the instability of these homogeneous bilayer systems towards the formation of density waves by studying the poles of the densitydensity response function. We have also studied the collective modes of these systems and found that the dispersion of their antisymmetric collective mode signals the emergence of the density wave instability. [Preview Abstract] 

T01.00071: Bose Fireworks 2.0. Jiazhong Hu, Lei Feng, Logan W. Clark, Cheng Chin When the scattering length of a BoseEinstein condensate is periodically modulated, atoms in the condensate can form numerous jets emitting in all directions, resembling fireworks. With an increasing modulation strength, we observe a highorder harmonic generation of matterwaves where emitted atoms form a multiring structure with quantized energy and momentum. Based on the evolution dynamics, we find that atoms in the high order rings originate from multiple scattering processes.~With the assistance of~pattern recognition, we identify a unique 10jet pattern in the emission that reveals intricate correlations between atomic populations in different momentum modes. We propose that the jet pattern is a result of Bose stimulation of secondary collisions into modes with macroscopic population. [Preview Abstract] 

T01.00072: Quench dynamics of two ultracold atoms Q. Guan, D. Blume, V. Klinkhamer, R. Klemt, P. Preiss, S. Jochim Ultracold atoms provide an ideal platform for studying quantum correlations with single atom resolution. This contribution considers the simplest nontrivial system, namely two interacting atoms. Starting from a welldefined initial state, the system is quenched by instantaneously weakening the external confinement while simultaneously modifying the trapping geometry. The time evolution following the quench is characterized by the formation of an intriguing fringe pattern. Experimental and theoretical results are compared and a physical picture for the quench dynamics is developed. [Preview Abstract] 

T01.00073: Efficient implementation of a gray optical molasses for subDoppler cooling of lithium6 atoms Christine Satter, Senmao Tan, Kai Dieckmann Alkalimetal atoms are prime candidates for studies of degenerate quantum gases and standard magnetooptical trapping and cooling of these elements to the Doppler limit is conventionally done on the $D_2$ transition. However, standard subDoppler cooling techniques are not effective for lithium because of this species' unresolved hyperfine structure in the excited state. In our experiment, a gray optical molasses operating on the $D_1$ atomic transition is applied to cool a cloud of Li6 atoms to subDoppler temperatures. A new laser setup was constructed to produce the light on the $D_1$ wavelength. For convenient integration into the preexisting laser system, a scheme is used where $D_2$ and $D_1$frequency light beams rapidly take turns injection seeding the same diode laser. A beat system is set up that allows us to monitor the correct seeding of the diode laser during the different stages of the experimental sequence, in a fast, timeresolved manner. We observe cooling of the atoms from 380 to 32 $\mu\textrm{K}$. A characterization of the gray molasses is presented and the results are compared to those previously reported in gray molasses experiments. Finally, we discuss the efficacy of atomic transfer from the molasses into a twobeam crossed optical dipole trap. [Preview Abstract] 

T01.00074: Towards high phase space density via cavity cooling YuTing Chen, Yiheng Duan, Pablo Solano Palma, Mahdi Hosseini, Kristin Beck, Vladan Vuletic Optical cooling of atoms to achieve BoseEinstein condensation has been recently demonstrated via degenerate Raman sideband cooling [1]. This technique is faster and more efficient than conventional evaporative cooling. However, it is challenging to implement Raman sideband cooling in atoms or molecules with complicated internal energy structures. A way to overcome this limitation is cavity cooling. Using this method, cooling many atoms down to the theoretical limit has been demonstrated with more efficiency than evaporative cooling [2]. Remarkably, cavity cooling is independent of the internal atomic structure. These advantages make cavity cooling a potential technique to generate Bose Einstein condensates that can be applied to many different atomic species. In this work, we report our experimental progress towards reaching high phase space density via cavity cooling. [1] Science 358, 10781080 (2017) [2] Phys. Rev. Lett. 118, 183601 (2017) [Preview Abstract] 

T01.00075: Coverage dependence of carbon induced workfunction changes on Au(110)  (2 \texttimes 1). Hossein Z. Jooya, Eunja Kim, Dustin A. Hite, Kyle S. McKay, David P. Pappas, Phil F. Weck, Hossein R. Sadeghpour The fluctuating dipole moment from diffusing adatoms on iontrap electrode surfaces is a possible source of motional heating of trapped ions. This diffusion noise varies quadratically with the variation of the surface dipole moment. Experimentally, such dipole moment changes are determined by measuring the variation of the surface work function caused by adatomsurface interactions. In this study, the dependence of the work function on carbonadatom coverage on Au(110)(2 \texttimes 1) is investigated. The experimentally measured workfunction variation with carbon coverage is compared to calculations making use of a density functional method. The surface dynamics of carbon adatoms is studied by abinitio molecular dynamics. The contribution of various available adsorption sites on the observed work function is analyzed. [Preview Abstract] 

T01.00076: Optimizing ion trap design with improved potential field and molecular dynamics simulation Liangyu Ding, Xiang Zhang, Qiuxin Zhang, Danna Shen, Xiran Sun, Wei Zhang There is increasing interest in improving trapped ions lifetime and the controllability of their equilibrium positions for large scale quantum computation and simulation. Thus a welldesigned ion trap is especially important. Here, we present a numerical toolset to find optimal trap parameters. Trap potential field is solved via boundary element method with improved precision. Trapped ion system is chaotic because of the nonlinear Coulomb interaction, thus any computational error will accumulate exponentially with the evolution time. We separate the energy of the system from such errors by simulating molecular dynamics via position extended ForestRuth integration method, which preserve timereversal symmetry. System characteristics such as equilibrium positions and Coulomb crystal phase transitions are calculated after considering background collisions and laser interactions. The relationship between RF heating rate and geometrical parameters of electrodes, the surface roughness and the ambient electromagnetic noise is estimated through simulation. Finally, suitable design parameters are found through the optimization algorithm, and a series of high performance ion traps are designed and fabricated. [Preview Abstract] 

T01.00077: High Efficiency Light Collection for Use in a Modular Quantum Network Allison Carter, Martin Lichtman, Clayton Crocker, Ksenia Sosnova, Sophia Scarano, Christopher Monroe Remote entanglement of ions is useful as a tool in the development of a scalable quantum network. To generate entanglement, we collect and fiber couple the emitted photons from ions in separate vacuum chambers. We aim to achieve diffractionlimited light collection, imaging or fiber coupling with 10$\%$ of the emitted photons through the use of a number of supporting technologies. The objective lens is designed to work at 0.6 NA for both Yb$^{+}$ and Ba$^{+}$ light spanning wavelengths from 370 nm to 650 nm. We then correct residual aberrations from the vacuum chamber and lens system using a deformable mirror. A ShackHartmann wavefront sensor and Zernike polynomial decomposition of intensity can be used for initial settings of the mirror, and closedloop optimization is performed using feedback from photon counts through the fiber. [Preview Abstract] 

T01.00078: Velocity Dependence of the ARP Force Brian Arnold, Yifan Fang, Harold Metcalf The optical force on atoms from coherent momentum exchange using adiabatic rapid passage (ARP) has been shown to be much larger than the usual radiative force\footnote{X. Miao, Phys. Rev. A 75, 011402 (2007).}. To gauge its broader utility, we are measuring its velocity dependence, $F(v)$. We counterpropagate two beams from phaselocked lasers, perpendicular to an atomic beam, and measure the deflection of atoms out of the beam. The atomic velocity $v$ is simulated by oppositely detuning these lasers by $\pm \delta = \pm kv$ where $k \equiv 2\pi/\lambda$. We have been surprised to find that $F(v)$ is asymmetric about $v=0$, and are investigating a number of explanations for this observation. We further test the utility of the ARP force by measuring $F(v)$ over a range of interaction times. [Preview Abstract] 

T01.00079: EDM$^3$: a new search for the electron electric dipole moment using molecules in a matrix Eric Hessels, Marko Horbatsch, Amar Vutha Improved measurements of the electron electric dipole moment (eEDM) will strongly constrain the parameter space of new physics theories. Such experiments are especially important due to the dearth of new physics observations at highenergy colliders. 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 eEDMinduced electron spin precession, as well as the total number of molecules available over the course of a measurement. We present 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, Atoms 6, 3 (2018). [Preview Abstract] 

T01.00080: Searching for New CPViolating Hadronic Physics via Nuclear Magnetic Quadrupole Moments Nickolas Pilgram, Arian Jadbabaie, Avikar Periwal, Nicholas Hutzler The Baryon Asymmetry (BAU) of the universe, or imbalance between matter and antimatter, is a major outstanding problem in modern physics. The Sakharov conditions propose that the BAU results from physical processes that violate Charge Parity (CP) symmetry. CP violation can manifest itself as intrinsic permanent electric dipole moments (EDMs) and magnetic quadrupole moments (MQMs), though the predicted values of these moments from the Standard Model are insufficient to explain the BAU. Therefore, new sources of CP violation beyond the Standard Model (BSM) are required and can be probed in the lepton sector with electron EDM searches or in the hadron sector with nuclear MQM searches. Heavy polar molecules are an ideal system for probing these CP violating moments due to their extremely large internal electromagnetic fields which can be aligned in the laboratory frame. We discuss and experiment to measure nuclear MQMs in deformed nuclei using heavy polar molecules with internal comagnetometers  closely spaced opposite parity states which provide natural systematic error rejection. This MQM measurement could probe new hadronic physics at the TeV scale, with significant room for future improvements. [Preview Abstract] 

T01.00081: Searching for New Physics Using LaserCooled Polyatomic Molecules Arian Jadbabaie, Ivan Kozyryev, Avikar Periwal, Nickolas Pilgram, Nicholas Hutzler The large, internal electromagnetic fields of polarized molecules make them a powerful platform for precision measurement searches of physics beyond the standard model (BSM). While previous BSM searches have been performed with cold beams of diatomic molecules, which were able to probe TeV energy scales, lasercooled molecules offer orders of magnitude improvement in measurement time, with the potential to increase sensitivity to PeV scales. Unfortunately, lasercoolable diatomic species lack easily polarizable parity doublets. Such socalled internal comagnetometer states are a prerequisite for significantly enhanced systematic error rejection. Conversely, certain polyatomic molecules, such as linear triatomics or symmetric tops, exhibit both internal comagnetometers and electronic structures favorable to lasercooling, making them ideal candidates to extend the frontier of precision measurement searches. We propose combining lasercooling and cryogenic buffer gas cooling of YbOH to search for new hadronic and leptonic physics at the PeV scale. Lasercooled, easily polarized molecules also have applications in fields beyond precision measurement, such as quantum information, manybody quantum dynamics, and ultracold chemistry. [Preview Abstract] 

T01.00082: Apparatus for LaserCooling and Trapping Potassium Kellan Kremer, Matt Butschek, Jonathan Wrubel We present our apparatus for laser cooling and trapping potassium atoms. The apparatus utilizes a compact permanentmagnet 2D magnetooptical trap (MOT) as a lowvelocity intense source for the 3D MOT. The science chamber is an octagonal glass cell chosen to allow for precise control over the magnetic field at the atoms. The goal of the apparatus is to study the hyperfine (radiofrequency) Feshbach resonance, which requires excellent magnetic field stability. [Preview Abstract] 

T01.00083: Photoassociation spectroscopy and AtomMolecule Coherence in Ultracold LiYb Mixtures Jun Hui See Toh, Alaina Green, Khang Ton, Subhadeep Gupta The nonbialkali LiYb molecule possesses both electric and magnetic dipole moments, and the unpaired electron degree of freedom could be utilized towards magnetic trapping of ultracold molecules as well as tuning of molecular collisions and reactions. We present photoassociation (PA) spectroscopy of ground and excited state potentials of the ${}^6$Li${}^{174}$Yb molecule. We have observed several vibrational states in an excited state potential using 1photon PA spectroscopy, detected as atom loss in an ultracold mixture of Li and Yb atoms confined in an optical dipole trap. Using 2photon PA to couple the excited state to the ground state, we have observed several vibrational states in the ground state potential. The binding energies, linewidths, and the line strengths will be reported. We have also observed narrow atommolecule dark state resonances in coherent twophoton spectroscopy. We intend to utilize these dark states to perform Stimulated Raman Adiabatic Passage (StiRAP) to create ultracold samples of LiYb in the electronic ground state. [Preview Abstract] 

T01.00084: Undergraduate Research Laboratory for Controlling Atoms with Frequency Modulated Light Matthew Wright, Tanner Grogan, James St. John, Tara Pena We have developed an undergraduate research lab for controlling atoms with pulsed frequency chirped laser light. We can tune the chirp rate to 1 GHz in 4 ns and pulse the laser as short as 3 ns. We will discuss recent results of undergraduate research probing interference in spontaneous emission in dilute Rb gases with pulsed lasers. We will also discuss how we plan to use this apparatus to explore standard atomic physics experiments such as STIRAP, ARP, etc and use it to conduct future research on coherently controlling photonassisted ultracold collisions. [Preview Abstract] 

T01.00085: An efficient 2D array of bluedetuned optical traps Trent Graham, Xiaoyu Jiang, Cody Poole, Yuan Sun, Martin Lichtman, Mark Saffman We demonstrate a 2D lattice of bluedetuned optical traps which uses laser power efficiently, is tolerant to perturbations in beam alignment, and is insensitive to interferometric phases. Blue traps have several advantages over red traps despite requiring a more complicated beam geometry. Since atoms in a blue trap sit at an intensity minimum, Stark shift noise and sitetosite calibrations are minimized. However, constructing a blue lattice which efficiently converts laser power into trap depth, is challenging. For example, a lattice of bottle beams is inefficient because neighboring sites are separated by two walls, limiting the number of traps that can be formed. An array of tightly spaced Gaussian beams is a more efficient blue trap, but the trap potentials are susceptible to alignment perturbations. We demonstrate an array which uses diffractive optical elements to create a crosshatched pattern of lines in the focal region where the atoms are trapped in up to 121 sites. This ``line array'' is almost twice as efficient as the Gaussian beam array and is more resilient to perturbations in beam alignment. [Preview Abstract] 

T01.00086: Critical vortex shedding in a strongly interacting fermionic superfluid Jee Woo Park, Bumsuk Ko, Yongil Shin Quantized vortices in superfluids are fundamental topological excitations whose creation and dynamics reveal the underlying thermodynamic and transport properties of the medium. Here, we report on the experimental study of the critical velocity for vortex shedding in a strongly interacting fermionic superfluid. The sample consists of a balanced mixture of two lowest hyperfine states of $^{6}$Li atoms prepared in a highly oblate trap near a broad $s$wave Feshbach resonance. By moving a repulsive optical obstacle through the condensate and directly imaging the vortices after time of flight, we measure the critical velocity for vortex shedding as a function of the interaction parameter 1/$k_{F}a$ and the obstacle travel distance $L$. The critical velocity displays markedly different behaviors in the two limits of $L$. For short $L$, it shows a pronounced peak near unitarity, whereas for long $L$ the peak is strongly suppressed, implying that the onset of drag force occurs at a lower velocity and that the increase of the drag force with velocity is slow near unitarity. Further comparison of the measured critical velocity to the speed of sound and the pair breaking velocity, and the application of the periodic shedding model to determine the onset of the drag force will be discussed. [Preview Abstract] 

T01.00087: Spinorbit coupling and superfluidity in ultracold quantum gases Benjamin Smith, Logan Cooke, Anindya Rastogi, Taras Hrushevskyi, Erhan Saglamyurek, Lindsay LeBlanc Considering BECs of $^{87}$Rb and $^{39}$K, we explore the effects of spinorbit coupling on the superfluidity of this ultracold quantum gas. In particular, we are interested in the analogue of a spinHall effect in this system, where, effectively, two different spin states experience different magnetic fields. We study this system numerically using the GrossPiteavskii equation, and find that various ``structures’’ emerge depending on the spinorbit, trap, and interaction parameters, such as the formation of oppositely rotating vortices in the two different spin components, or stripes, or spindomain formation. We discuss progress towards realizing this system with our BEC experiments in the laboratory. [Preview Abstract] 

T01.00088: Toward MagnetoOptical Trapping of Polyatomic Molecules Louis Baum, Ivan Kozyryev, Zoe Zhu, Phelan Yu, John M. Doyle Three dimensional confinement of atoms inside a magnetooptical trap (MOT) revolutionized atomic physics and along with evaporative cooling led to the development of ultracold atomic gases in the quantum degenerate regime. Recently, groundbreaking experimental and theoretical work in molecular physics culminated with the creation of MOTs for diatomic molecules trapped below 1 mK [13]. Building on these achievements and our previous work on laser cooling of polyatomic molecules [4], we will present our progress towards creating a RF MOT of a triatomic radical, CaOH. Our experimental and theoretical results indicate that laser cooling can also be extended to hexatomic symmetric top molecules, e.g. CaOCH$_{\mathrm{3}}$. Nonzero vibrational angular momentum of linear triatomics and finite projection of rotational angular momentum onto the body frame of symmetric top molecules result in linear Stark shifts, enabling novel quantum science applications. [1] Norrgard et al., PRL 116, 063004 (2016). [2] Truppe et al., Nat. Phys. 13, 1173 (2017). [3] Anderegg et al., PRL 119, 103201 (2017). [4] Kozyryev et al., PRL 118, 173201 (2017). [Preview Abstract] 

T01.00089: Optical Dipole Trapping of Holmium Christopher Yip, Donald Booth, Huaxia Zhou, Jeffrey Collett, James Hostetter, Mark Saffman Neutral Holmium’s 128 ground hyperfine states, the most of any nonradioactive element, is a testbed for quantum control of a very high dimensional Hilbert space, and offers a promising platform for quantum computing. Previously we have cooled Holmium atoms in a MOT on a 410.5 nm transition and characterized its Rydberg spectra. We report here on the first optical dipole trapping of Holmium with a 532 nm wavelength trap laser. The trap lifetime is close to 1 sec., limited by photon scattering from nearby transitions. The trapped atoms are used to measure the dynamic scalar and tensor polarizabilities which are compared with calculations based on measured oscillator strengths. We also report progress towards narrow line cooling and magnetic trapping of single atoms. [Preview Abstract] 

T01.00090: Atomic properties of actinide ions with particlehole configurations Marianna Safronova, Ulyana Safronova, Mikhail Kozlov We study the effects of higherorder electronic correlations in the systems with particlehole excited states using a relativistic hybrid method that combines configuration interaction and linearized coupledcluster approaches. We find the configuration interaction part of the calculation sufficiently complete for eight electrons while maintaining good quality of the effective coupledcluster potential for the core. Excellent agreement with experiment was demonstrated for a test case of La$^{3+}$. We apply our method for homologue actinide ions Th$^{4+}$ and U$^{6+}$ which are of experimental interest due to a puzzle associated with the resonant excitation Stark ionization spectroscopy (RESIS) method. These ions are also of interest to actinide chemistry and this is the first precision calculation of their atomic properties. [Preview Abstract] 

T01.00091: Demonstration of metrologically relevant spinsqueezing in free space with an ensemble of $^{87}$Rb atoms Yunfan Wu, Onur Hosten, Rajiv Krishnakumar, Julian Martinez, Benjamin Pichler, Mark Kasevich Entangled atomic states such as spinsqueezed states can overcome the atomic projection noise that limits the precision of atomic sensors. Various experiments have successfully demonstrated such states. For precision sensing applications requiring the atoms to be freely moving, such as fountain clocks and atom interferometers, the homogeneity of the prepared squeezed states is crucial for their successful retrieval. In this work, we initially generated 12dB spinsqueezed states using an opticalcavity that uniformly interacts with 500,000 $^{87}$Rb atoms trapped in an optical lattice. Then we released these atoms into free space and recaptured them back into the lattice after a variable duration. The final state of the atoms was then measured with the help of the cavity. We characterized the degradation in squeezing as a function of release time, and modeled it including the effects of atom loss and loss in atomcavity coupling homogeneity. We demonstrated the retrieval of spinsqueezing in free space for up to 2ms limited by our ability to recapture the atoms. This result is a crucial step towards implementing metrologically relevant spinsqueezed atomic sensors in free space. [Preview Abstract] 

T01.00092: Quadratic optomechanical interaction in the reversed dissipation regime Hyojun Seok, Jae Hoon Lee Cavity optomechanics is an important platform for which the interaction between light and the motional degrees of freedom of a mechanical oscillator can be engineered for specific objectives such as cooling the mechanical state or amplifying the electromagnetic field. Here we theoretically examine an optomechanical resonator coupled to both mechanical and optical reservoirs in the reversed dissipation regime. We show that in the case of quadratic coupling between the electromagnetic field and mechanical oscillator, the linewidth of the noise spectra of the cavity field is dependent on the mean phonon number of the mechanical oscillator. Using advanced fabrication methods for optomechanical devices, we propose to develop reservoir engineered optomechanical devices for temperature measurement in the quantum regime. [Preview Abstract] 

T01.00093: Hydrodynamics in a uniform Fermi Gas Xin Wang, Lorin Baird, Stetson Roof, John Thomas We are working towards trapping a strongly interacting ultracold Fermi gas of $^6$Li atoms in a uniform box potential. The potential is created by applying repulsive bluedetuned beams shaped by Digital Micromirror Devices (DMD). The DMDs are more flexible compared to diffractive optics as they are capable of changing the beam shape dynamically. Uniform traps provide advantages over traditional Gaussian beam traps by avoiding averaging over a spatial varying density in light absorption detection. This will allow us to conduct experiments studying quantum hydrodynamic properties in near ideal configurations. We plan to study propagation of supersonic and subsonic shockwaves, sound waves and energy transport in outofequilibrium systems. [Preview Abstract] 

T01.00094: Towards studies of the BECBCS crossover in a disordered environment Benjamin Nagler, Benjamin Gänger, Jan Phieler, Artur Widera Ultracold atoms have proven to be an invaluable tool for the precise investigation of quantum systems that are difficult to access otherwise. One example are interacting quantum particles in disordered potentials, which exhibit compelling phenomena like Anderson or manybody localization. In order to examine such systems, we have set up a new experiment in which we will immerse a degenerate Fermi gas of lithium atoms into an optical disorder potential, so called speckle. By addressing a magnetic Feshbach resonance, the atomic interaction parameter can be tuned to arbitrary values, which allows us to access both bosonic and fermionic superfluidity. One major question we will address is how the impact of disorder evolves as interactions are switched on and tuned from repulsion to attraction. I will present experimental details as well as the current status of the project. [Preview Abstract] 

T01.00095: Universal features for spin dipolar losses in atomic bose gases Qi Liu, YuanGang Deng, YiQuan Zou, Su Yi, Meng Khoon Tey, Li You Like elastic collisions, inelastic collisions provide exquisite information on interaction potentials. In an external magnetic field ($B$), spatially confined atoms can gain sufficient kinetic energies to escape due to spin flip inelastic collisions from magnetic dipoledipole interaction (MDDI). This work reports combined experimental and theoretical studies of Bdependent loss lineshapes for ground state (F=1) $^{87}$Rb atoms in a BoseEinstein condensate (BEC) with high atom number resolution. The measured loss rates are explained using wave functions from a semianalytic quantumdefect theory (QDT) [1,2], which is consistent with numerical coupledchannel (CC) calculations. In the limit of large swave scattering length ($a_s$), the observed interesting features constitute a universal form with a ``dip" $B_\vee$ (for positive $a_s$) and a ``peak" $B_\wedge$ (for either positive or negative $a_s$) in the respective loss channels for one or two atom spin flips. The specific values of $B_\vee$ and $B_\wedge$ are determined predominantly by $a_s$ and also by the dwave centrifugal barrier height $V_{l=2}$. \\\\ {[1] Gao, B, Phys. Rev. A 58, 1728 (1998); Phys. Rev. A 64, 010701(R) (2001); Phys. Rev. A 78, 012702 (2008).\\ {[2] Gao, B et al., Phys. Rev. A 72 042719 (2005).}} [Preview Abstract] 

T01.00096: Quantum Interferometry with MicrowaveDressed Spinor BoseEinstein Condensates in the Regime of Long Evolution Times Shan Zhong, Qimin Zhang, Isaiah Morgenstern, Hio Giap Ooi, Logan Baker, Justin kittel, Arne Schwettmann We recently achieved alloptical generation of Na spinor BoseEinstein condensates (BEC) in our crossed faroff resonant trap at 1064 nm. Using our BEC, we experimentally investigate atom interferometry based on spinexchange collisions in the regime of long evolution times where the Bogoliubov and truncated Wigner approximations break down, and compare the results with our numerical simulations. Spinexchange collisions in the F= 1 spinor BoseEinstein condensate can be precisely controlled by microwave dressing, and generate pairs of entangled atoms with magnetic quantum numbers $m_F$= +1 and $m_F$= 1 from pairs of $m_F$= 0 atoms. Spin squeezing created by the collisions can reduce the noise in an atom interferometer below the shot noise limit. For long evolution times, $t\gg h/c$, where $c$ is the spindependent interaction energy, $c\simeq h\cdot30$ Hz, there are large numbers of atoms with $m_F$= +1 or $m_F$= 1 in the arms of the interferometer, allowing for easier detection via SternGerlach timeofflight absorption imaging. [Preview Abstract] 

T01.00097: Cooperative shielding in threedimensional lattices Joshua T Cantin, Tianrui Xu, Roman V Krems Cooperative shielding is the phenomenon that can make quantum systems with longrange interactions behave effectively as those with shortranged interactions. Cooperative shielding has been previously demonstrated for both singleparticle and manybody systems in \emph{one}dimensional (1D) lattices. We demonstrate that cooperative shielding extends to singleparticle systems with \emph{isotropic} longrange hopping in \emph{three}dimensional (3D) lattices. We analytically diagonalize a Hamiltonian containing isotropic longrange hopping terms of the form $r^{\alpha}$ for a 3D lattice, under periodic boundary conditions, and where $\alpha$ is an arbitrary, real constant. We find that the obtained energy level structure is analogous to that observed in 1D. We also find that, for the 3D system of sidelength $N$, the shielding gap responsible for cooperative shielding diverges as $\Delta \propto N^3$, in contrast to the 1D case where $\Delta \propto N$. We further demonstrate, via numerical diagonalization, that cooperative shielding also extends to 3D systems with open boundary conditions. [Preview Abstract] 

T01.00098: Progress toward a highperformance ultracold dysprosium apparatus for quantum simulation experiments William Lunden, Michael Cantara, Li Du, Pierre Barral, Alan O. Jamison, Wolfgang Ketterle Dysprosium, which possesses both the largest magnetic dipole moment of any atomic species and a variety of closed transitions compatible with standard laser cooling techniques, has in recent years proven itself to be a powerful platform for ultracold experimental studies of quantum systems with dipolar interactions. We report on the construction of a new apparatus for ultracold dysprosium experiments with a number of performanceenhancing design features, including lownoise custom control electronics and nonmagnetic vacuum components and optomechanics. We also report on progress toward our first experimental goals: photoassociation spectroscopy of a trapped nondegenerate gas, which will offer valuable insight into the interatomic interaction potential; and a 2D spinorbit coupled degenerate Fermi gas, which would be a first realization of 2D spinorbit coupling in a system with dipolar interactions. [Preview Abstract] 

T01.00099: Ground state of a Fermi gas with tilted dipoles Antun Balaz, Vladimir Veljic, Aristeu R. P. Lima, Simon Baier, Lauriane Chomaz, Francesca Ferlaino, Axel Pelster In the presence of an anisotropic and longrange dipoledipole interaction, the Fermi sphere of an ultracold Fermi gas deforms into an ellipsoid. Recently, it was experimentally observed in such systems that the shape of the Fermi surface follows the rotation of the dipoles when they are tilted [1]. Here we generalize the HartreeFock meanfield theory of Refs.~[2, 3], where the dipoles were assumed to be parallel to one of the trap axes, to an arbitrary orientation of the dipoles and obtain the groundstate ThomasFermi radii and momenta. The calculated angular dependence of the Fermi surface deformation shows good agreement with experimental observations. We also find that the angular dependence of the aspect ratio turns out to be a direct consequence of the dipole tilting. \newline [1] K. Aikawa, et al., Science {\bf 345}, 1484 (2014).\newline [2] F. W\"{a}chtler, et al., Phys. Rev. A {\bf 96}, 043608 (2017).\newline [3] V. Velji\'{c}, et al., Phys. Rev. A {\bf 95}, 053635 (2017). [Preview Abstract] 

T01.00100: Towards twodimensional quantum gases of strongly dipolar molecules Aden Lam, Niccolo Bigagli, Claire Warner, Darby Bates, Sebastian Will In recent years, ultracold atoms have been successfully used to investigate strongly interacting quantum manybody systems. A new frontier is opened up by ultracold molecules. In particular, heteronuclear molecules in the rovibrational ground state with tunable dipolar interactions make the study of quantum systems with strong longrange interactions accessible and constitute a promising system for quantum simulation. At Columbia, we are constructing a new experimental setup geared to create and study novel phases in twodimensional quantum systems of ultracold dipolar molecules. In a regime where repulsive dipolar interactions dominate, the emergence of a selforganised 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. In our setup, we will use DC and AC electric fields to control the dipolar interactions. In addition, we will be able to observe 2D quantum phases via high resolution imaging. [Preview Abstract] 

T01.00101: Feshbach spectroscopy and dualspecies BoseEinstein condensation of $^{23}$Na  $^{39}$K mixtures Kai Voges, Torben Schulze, Torsten Hartmann, Philipp Gersema, Alessandro Zenesini, Eberhard Tiemann, Silke Ospelkaus Ultracold polar ground state molecules are a powerful tool for the investigation of a wide range of physical phenomena as quantum chemical processes or exotic dipolar quantum phases. One way to prepare ultracold ground state molecules is based on a twophoton coherent Raman transfer starting from ultracold weaklybound Feshbach molecules. Here, we report on magnetic Feshbach resonance loss spectroscopy in all possible combinations of hyperfine sublevels with an ultracold atomic mixture of $^{23}$Na and $^{39}$K. We use our results to refine potential energy curves for bosonic NaK molecules. Further, we identify and discuss the suitability of different magnetic field regions for the purposes of sympathetic cooling of $^{39}$K in a bath of $^{23}$Na atoms. We use our findings for the demonstration of dualspecies degeneracy in the $^{23}$Na $^{39}$K mixture. The two condensates are created simultaneously by evaporation at a magnetic field of about 150$\,$G, which provides sizable intra and interspecies scattering rates needed for fast thermalization. Finally, we discuss the pathway for the production of Feshbach molecules as well as the twophoton Raman transfer to the rovibronic ground state. [Preview Abstract] 

T01.00102: Formation of heteronuclear Feshbach molecules in microgravity Jose D'Incao, Jason Williams NASA’s Cold Atom Laboratory (CAL) is a multiuser facility scheduled for launch to the ISS in 2018. Our flight experiments with CAL will characterize and mitigate leadingorder systematics in dualatomicspecies atom interferometers in microgravity relevant for future fundamental physics missions in space. As part of the initial state preparation for interferometry studies, here, we study association and dissociation of weakly bound heteronuclear Feshbach molecules, through magnetic field ramps, for expected parameters relevant for the microgravity environment of CAL. This includes temperatures on the picoKelvin range and atomic densities as low as $10^8$/cm$^3$. In order to qualitatively explore this problem we developed a theoretical model in which a few atoms are subjected to an artificial trapping potential whose trap frequency is adjusted to reproduce the average interatomic distance in the ultracold gas. This model has been successfully used to analyze previous experiments in molecular formation and we will extent such approach to include various quantitative aspects related to the fewbody physics in the problem. Within this model we can obtain the efficiency for molecular association and dissociation, as well as estimate the generated heating during the field ramps. [Preview Abstract] 

T01.00103: Evaporation of Ultracold Polar Molecules in an Optical Lattice William Tobias, Luigi De Marco, Giacomo Valtolina, Kyle Matsuda, Jacob Covey, Jun Ye Ultracold polar molecules interact via longrange, anisotropic dipoledipole potentials, allowing the realization of novel manybody quantum phases. Proposed areas of study for polar molecule lattice systems include spinorbit coupling, topological phases, and exotic superfluidity. Having recently produced a bulk gas of greater than 40,000 ground state potassium rubidium molecules on a redesigned apparatus, we present progress towards evaporation of molecules in a onedimensional optical lattice. To manipulate molecular rotational states and control interactions, the apparatus contains invacuum electrodes for generating large (30 kV/cm) homogeneous fields and field gradients as well as microwave fields. Future experiments will include preparation of lowentropy optical lattice samples and microscopy of dipolar spin Hamiltonians. [Preview Abstract] 

T01.00104: Spectroscopy of Rb atoms in metastable groundRydberg molecules and in highintensity laser traps Cody Patterson, Sophia TenHuisen, Jamie MacLennan, David Anderson, Georg Raithel Stable and rapid laserlocking schemes with wide tunability are important in a variety of spectroscopic measurements. Here, we present the progress on developing an AOMetalon laser scanning device to be used in future experiments. The device selects the 1st order of a 960nm laser which subsequently passes through an etalon. By tuning the RF frequency of the AOM driver, we angletune the beam passing through the etalon. The tuning range is calculated to be $\sim$ 800 MHz in laser frequency per MHz of RF frequency. This device will be used to stabilize lasers in future experiments that aim to measure Rb polarizabilities and Rb molecular spectra. In context with the planned molecular spectroscopy, we additionally present calculations of nonadiabatic processes between circularstate Rydberg and groundstate atoms. [Preview Abstract] 

T01.00105: Pulsed Ring Stark Deceleration and OH Molecules in External Fields for CoTrapping Experiments Jason Bossert, Yomay Shyur, John Gray, Heather Lewandowski Cotrapped collision experiments offer one of the best windows into how atoms and molecules interact at cold temperatures. However, one limitation of cotrapped collision experiments is the molecular density within the trap. First, we present an experimental realization of a ringgeometry Stark decelerator using both continuous and discrete electric fields. New ringgeometry Stark decelerators with continuously varying electric fields produce a more intense molecular source than conventional crossedpin geometry decelerators. However, the electronic requirements to produce a continuously varying electric field are substantial. We show that operating a ringgeometry Stark decelerator with discretely varying electric fields not only eliminates the need for complicated analog electronics, but also opens a new, low velocity, higherdensity regime for moderate peak electric fields. Second, we present a study on the effects of external electric and magnetic fields on Stark decelerated cold OH molecules. Our study of OH in external fields lays the foundation for future cotrapped collision studies. [Preview Abstract] 

T01.00106: Benchmarking a stimulated force for molecular beams with Rb atoms Scarlett Yu, Xueping Long, Andrew Jayich, Wesley C. Campbell The rich internal structures of molecules make ultracold molecules attractive candidates for sensitive probe of fundamental physics, but for the same reason they are hard to decelerate, cool and trap, as the many possible spontaneous emission paths limit the ability to optically decelerate molecules to trappable speed. We demonstrate a stimulated force solution to this problem using pulses generated from a modelocked laser. A molecular beam can be first excited by a counterpropagating ``pump'' pulse, then driven back to the initial ground state by a copropagating ``dump'' pulse via stimulated emission. The delay between the pump and dump pulse is set to be shorter than the excited state lifetimes in order to limit decays to dark states. We report results of our benchmarking this stimulated force by accelerating a cold sample of neutral Rb atoms. [Preview Abstract] 

T01.00107: An optogalvanic flux sensor for trace gases Johannes Schmidt, Markus Fiedler, Denis Djekic, Patrick Schalberger, Holger Baur, Robert Loew, Tilman Pfau, Jens Anders, Norbert Fruehauf, Edward Grant, Harald Kuebler We demonstrate the applicability of a new kind of gas sensor based on Rydberg excitations. From an arbitrary probe gas the molecule in question is excited to a Rydberg state, by succeeding collisions with all other gas components this molecule gets ionized and the emerging electron and ion can then be measured as a current, which is the clear signature of the presence of this particular molecule. As a first test we excite Alkali Rydberg atoms in an electrically contacted vapor cell [1,2] and demonstrate sensitivities down to 100 ppb on a background of $N_2$. We investigate different amplification circuits, ranging from solid state devices on the cell to thin film technology based transimpedance amplifiers inside the cell [3]. For a real life application, we employ our gas sensing scheme to the detection of nitric oxide in a background gas at thermal temperatures and atmospheric pressure.\\ $[1]$ D. Barredo, et al., \textit{Phys. Rev. Lett.} \textbf{110}, 123002 (2013)\\ $[2]$ R. Daschner, et al., \textit{Opt. Lett.} \textbf{37}, 2271 (2012)\\ $[3]$ J. Schmidt, et al., \textit{AMFPD} \textbf{24}, 296298 (2017) [Preview Abstract] 

T01.00108: Simulations of directed field ionization Jason J. Bennett, Bianca R. Gualtieri, Zoe A. Rowley, Vincent C. Gregoric, Thomas J. Carroll, Michael W. Noel In selective field ionization, a slowly rising electric field pulse ionizes a Rydberg atom such that lowerenergystate electrons are generally detected later in time than higherenergystate electrons. As the electric field increases, the Rydberg electron's amplitude spreads among many nearby energy levels by splitting and recombining at hundreds of avoided crossings. In ``directed field ionization,'' we use a genetic algorithm to engineer perturbations in the pulse and using this technique we have demonstrated control of the shape of the timeresolved ionization signal\footnote{V. Gregoric, \textit{et al.}, Phys. Rev. A \textbf{96}, 023403 (2017)}. We have recently extended this approach to separate the previously unresolved signal from two nearby initial energy levels (see V. Gregoric's poster in this session). We present simulations of the pulse evolution which allow us to visualize the electron's path to ionization and the shape of the wave function and we compare our calculations to experimental results. [Preview Abstract] 

T01.00109: Characterization of chargeinduced optical bistability in thermal Rydberg vapor Daniel Weller, Nico Sieber, Alban Urvoy, Tilman Pfau, Robert Loew, Harald Kuebler Rydberg spectroscopy in thermal vapor has gained an increased popularity due to its promising applicability for integrated devices, e.g. in the context of sensing applications. Under certain conditions, the EITlike excitation to Rydberg state features a bistable behavior [1]. By performing two experiments with rubidium and cesium vapor, we are able to shed light on the underlying interaction mechanism causing the nonlinear behavior [2]: Due to different properties of these two atomic species, we conclude that the large polarizability of Rydberg states in combination with electric fields of ionized Rydberg atoms is the relevant interaction mechanism. In rubidium, we directly measure the electric field in a bistable situation via twospecies spectroscopy, thereby exploiting the DCStarkshift on a second Rydberg state. In cesium, we make use of the different sign of the polarizability for different lstates, and apply electric fields. In contrast to previous interpretations [1,3], these experiments allow us to rule out dipoledipole interactions, and support our hypothesis of a chargeinduced bistability. Here, we also discuss our followup experiments, studying the plasma properties of the charged vapor that is created. [1] PRL 111, 113901, [2] PRA 94, 063820 [3] PRA 93, 06386 [Preview Abstract] 

T01.00110: Details and Observables of ThreeDimensional Scattering between Two Rydberg Polaritons Hyunwoo Lee, Chris Greene The properties and applications of Rydberg polaritons, whereby novel quantum optical phenomena can arise from combining the interactions between Rydberg atoms with control associated with electromagneticallyinduced transparency (EIT), have received copious attention recently. Previous works on scattering between two polaritons assumed a 1D geometry\footnote{P. Bienias, et al., Scattering resonances and bound states for strongly interacting Rydberg polaritons, Phys. Rev. A \textbf{90}, 053804 (2014)}, and then a 3D treatment was undertaken with the explicit goal of predicting the Efimov effect between three equalmass polaritons\footnote{M. J. Gullans, et al., Efimov States of Strongly Interacting Photons, Phys. Rev. Lett. \textbf{119}, 233601 (2017)}. We present a formalism for understanding the details of basic twopolariton scattering in three dimensions (including such observables as the cross section and scattering lengths), with the goal of supplementing the current theories of the bound states of Rydberg polaritons. [Preview Abstract] 

T01.00111: Enhancing optical densities in thermal microcells on demand Fabian Ripka, Maxim Leyzner, Harald Kuebler, Robert Loew, Tilman Pfau Thermal atom cells on the size of few micrometers are powerful devices in the realm of fundamental as well as applied research in atomoptics. To provide enough atoms in such small volumes, usually temperatures much larger than 300K have to be applied. However, this is accompanied with enhanced collisional effects and the excitation of surfacepolaritons as well as technical difficulties in the experimental setups due to large temperature gradients. We present an experimental approach exploiting the effect of lightinduced atomic desorption [1], similar to the work of [2]. Here atoms are desorbed from the glass surface via intense nspulses at 480 nm and contribute to the optical density of the cell, until they adsorb at the opposite window surface and get bound again. By this technique we trigger the number of atoms to many hundreds per cubic micrometer on ns timescale. We will report on systematic timeresolved optical measurements in a thermal rubidium microcell. We show possible applications and remaining questions to be answered. [1] Meucci et al., EPL 25, 639 (1993) [2] Atunov et al., Phys. Rev. A 67, 053401 (2003) [Preview Abstract] 

T01.00112: Modeling Paths of Launched Cold Rydberg Atoms in a CylindricallySymmetric Electric Field Anne Goodsell, Sasha Clarick, Rene Gonzalez We calculate the trajectories of launched cold Rydberg atoms in a cylindricallysymmetric electric field as we prepare to steer cold Rydberg atoms in the field of a charged wire. We cool and launch rubidium atoms, and we have already excited launched atoms using the twophoton pathway $5S\rightarrow5P\rightarrow5D$ with resonant photons. We are preparing to excite the Rydberg states with $n=35$, $m_j=7/2$, from the 5$D$ state. To predict the subsequent motion of atoms in Rydberg states we evaluate the acceleration derived from the spatiallydependent Stark shift. Atoms approaching the wire move through regions corresponding to positive and negative acceleration, dependent on the nonmonotonic energy shifts. The atoms will be deflected by the wire; some are captured and intersect the wire surface (or another chosen boundary). Our iterative calculations of the atoms' dynamics indicate that atoms launched with a large impact parameter can still be captured. For atoms traveling at 6 m/s toward a wire charged to 3 V, the critical impact parameter for capture is 65 $\mu$m, leading to a capture crosssection more than four times the geometrical crosssection of the wire. We characterize the capture crosssection for velocities and voltages relevant to our planned experiments. [Preview Abstract] 

T01.00113: FPGAControlled Versatile Microwave Source for Cold Atom Experiments Isaiah Morgenstern, Shan Zhong, Qimin Zhang, Logan Baker, Jeremy Norris, Bao Tran, Arne Schwettmann We present our FPGAcontrolled microwave source for controlling the timedependent microwavedressing of the ground state hyperfine levels of a BoseEinstein condensate. Our source is based on direct digital synthesis (DDS) of low frequency (MHz) signals, and singlesideband modulation (SSM) to bring these signals up to microwave frequencies (GHz). The DDS chip is controlled by a FPGA to allow versatile programming of fast, arbitrary, timedependent changes of amplitude, phase, and frequency. The frequency is upshifted by SSM with a stable 1.8 GHz microwave synthesizer. 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. Impedance matching of the antenna is accomplished with a stub tuner. The microwave source is modular so it can be easily reprogrammed and adjusted to fit a wide variety of experimental setups. [Preview Abstract] 

T01.00114: Polarization sensitive imaging of a spinor BoseEinstein condensate Maitreyi Jayaseelan, Joseph D. Murphree, Justin T. Schultz, Zekai Chen, Nicholas P. Bigelow With magnetic and optical techniques enabling the creation of interesting topological spin textures in spinor BoseEinstein condensates (BECs), the interaction and evolution of these systems has become a burgeoning field of research. However, the standard absorption imaging techniques ubiquitous in atomic physics experiments are completely destructive, making evolution studies difficult. Here we investigate a dispersive polarizationsensitive imaging method that allows access to the populations and coherences between spin states in the BEC, thereby enabling a full reconstruction of the spinor wavefunction. The tensorial nature of the linear atomic susceptibility allows us to utilize the polarization of the optical electric field to probe atomic properties by analyzing the transmitted optical polarization. Since this method may be nonresonant it is able to be minimally destructive, allowing repeated measurements on a single evolving BEC. Varying the parameters of the imaging system such as detuning and intensity of the imaging beam offers a way to characterize our procedure in terms of atom number loss and the signaltonoise ratios accessible in our system. [Preview Abstract] 

T01.00115: An Errorcorrected, Universal, Reconfigurable, Iontrap Quantum Archetype Kristin Beck, Marko Cetina, Michael Goldman, Laird Egan, Chris Monroe The EURIQA project is a collaboration between universities and industrial partners that is implementing a systematic, topdown approach to constructing a complex quantum processor based on trapped ions. As part of the LogiQ program, our goal is to use quantum error correction to realize an encoded logical qubit. The system uses Yb+ ions, which have an opticallyaccessible qubit state with long coherence times and gate fidelities exceeding 99$\%$ [1]. We will present the status of the development and integration of the stateoftheart system underway at JQI/UMD. Our system relies on microfabricated traps, parallel addressing of individual ions, and multispecies operation to address the challenges of implementing a logical qubit. [1] N. M. Linke et al., Proc. Natl. Acad. Sci. 114, 13 (2017) [Preview Abstract] 

T01.00116: Symmetryenriched BoseEinstein condensates in a spinorbitcoupled bilayer system JiaMing Cheng We consider fate of BoseEinstein condensation with timereversal symmetry and inversion symmetry in a spinorbitcoupled bilayer system. When these two symmetry operators commute, all single particle bands are exactly twofold degenerate in momentum space. Scattering in the twofold degenerate rings can relax spinmomentum locking effect resulting from spinorbit coupling, thus we can realize spin polarized plane wave phase even when interparticle interaction dominates. When these two operators anticommute, the lowest two bands may have the same minimal energy, which have totally different spin structures. As a result, competition between different condensates in these two energetically degenerate rings can give rise to interesting stripe phases with atoms condensed at two or four colinear momenta. We find that crossover between these two cases is accompanied by excited band condensation when interference energy can overcome the increased single particle energy in excited band. This effect is not based on strong interaction, thus can be realized even with moderate interaction strength. [Preview Abstract] 

T01.00117: Emergent universality at the tricritical point in a generalized Dicke model Youjiang Xu, Han Pu We show that the secondorder quantum order phase transition presented in the Dicke model in the thermodynamic limit can turn into firstorder one by breaking exchange symmetry between atoms. Landau theory of phase transition predicts that the tricritical point, which is the intersection between the firstorder and the secondorder phase transition boundaries, has different critical behavior than the other points on the critical line. However, we find that the relation between lowest excitation energy and the atomlight entanglement entropy is universal, though the order parameter doesn't possess universal properties. We show that it is due to the separation of classical and quantum degrees of freedom in the thermodynamic limit. Finitesize corrections tell us how the separation process takes place. [Preview Abstract] 

T01.00118: Modelindependent measurements of the excited state fraction in a sodium magnetooptical trap Jonathan Kwolek, Douglas Goodman, Samuel Entner, James Wells, Francesco Narducci, Winthrop Smith We perform a modelindependent measurement of the excitedstate population of a sodium (Na) magnetooptical trap (MOT) in a hybrid ionneutral trap. By photoionizing the the excited Na atoms within our MOT, we separately measure the photoionization rate using MOTfluorescence detection and by directly detecting the photoionized ions trapped in the LPT. A comparison of these two measurements yields a modelindependent measurement of the excited state fraction. We found that below a critical trappinglaser intensity the excitedstate fraction is accurately predicted by a twolevel model with an experimentally determined effective saturation intensity. Under a wide range of trapping conditions, we measured the effective saturation intensity to be $I_{\mathrm{se}} = 22.9(3)\;\textrm{mW}/\textrm{cm}^2$ for the typeI MOT and $I_{\mathrm{se}} = 48.9\;\textrm{mW}/\mathrm{cm}^2$ for the typeII MOT. These effective saturation intensities are both larger than the theoretically predicted value of $I_{\mathrm{sat}} = 13.4144(45)\;\textrm{mW}/\textrm{cm}^2$ for isotropicallypolarized light. Beyond the critical trappinglaser intensity, we find that the excited state fraction deviates from the twolevel model as a function of repumplaser power and magnetic field gradient. [Preview Abstract] 

T01.00119: Geometry, topology and control of spin1 atoms Bharath H. M., Matthew Boguslawski, Maryrose Barrios, Lin Xin, Deniz Kurdak, Michael Chapman Recent explorations of the physical manifestation of geometry and topology of the quantum phase space has been fruitful in that it revealed geometric, fault tolerant quantum control and topologically stable states of spatially extended traps of ultracold atoms. Here, we develop a new geometrical representation for spin1 quantum states and show its applicability to a range of interesting problems. Spin1 (and higher spin) quantum states are not simply defined with the spin vector, as in the spin1/2 case. The spin vector for higher spin could be anywhere on or inside the Bloch sphere, and at each point, there is a family of different states with the same spin vector. For spin1 systems, this ambiguity is resolved by considering the quantum spin fluctuations which, together with the spin vector, uniquely specify any spin1 quantum state. These fluctuations are represented geometrically with an ellipsoid surrounding the head of the spin vector. Using this representation, we uncover a number of exotic topologically stable states of a ring trap including those with fractional topological charge. Additionally, we develop a protocol for holonomic, faulttolerant, arbitrary control of the spin1 state and discuss applications to spin squeezing experiments. [Preview Abstract] 

T01.00120: Carving of atomic Bell states with an optical cavity Stephan Welte, Bastian Hacker, Severin Daiss, Stephan Ritter, Lin Li, Gerhard Rempe Optical resonators constitute an ideal platform to mediate interactions between distant matter qubits [1]. In a quantum network architecture, this is achieved by the exchange of photons between the network nodes, and in this way enables the generation of remote entanglement. Here we demonstrate how photons can likewise be used to generate local entanglement between matter qubits, neutral atoms in our case, in the same network node [2]. Such entangled states are a valuable resource in many quantum communication protocols. We implemented two protocols [3], both relying on the reflection of polarized light from the atomresonator system. Detection of a polarisation flip heralds the entanglement and postselection allows us to remove parts of the combined twoatom wave function, a method called carving. We achieve fidelities with the ideal Bell states of up to 90{\%}. Our entangling mechanism can be applied to any matter qubit with a closed optical transition and no individual addressing is required. [1] A. Reiserer, G. Rempe, Rev. Mod. Phys. 87, 1379 (2015). [2] S. Welte, B. Hacker, S. Daiss, S. Ritter, G. Rempe, Phys. Rev. Lett. 118, 210503 (2017). [3] A. Soerensen, K.Moelmer, Phys. Rev. Lett. 90, 127903 (2003). [Preview Abstract] 

T01.00121: Progress towards a Hybrid Rydberg Atom, Superconductor Quantum Interface Donald Booth, Juan Bohorquez, Joshua Isaacs, Matthew Beck, Robert McDermott, Mark Saffman Hybrid quantum computation bridges disparate quantum technologies in order to achieve fast gates with long coherence times. We present progress towards a hybrid quantum interface between single atoms and microwave excitations of a superconducting coplanar waveguide (CPW) resonator. The hybrid interface is based on trapping single Cesium atoms in a 4K cryostat in close proximity to the CPW. Twophoton excitation via the $6S_{1/2} \rightarrow 5D_{5/2}$ quadrupole transition prepares $90P_{3/2}$ Rydberg states that are strongly coupled to excitations of the CPW. We have completed construction on a new Ultra High Vacuum chamber and optical system for atom trapping, transport, and excitation. We demonstrate results for single atom trapping and Rydberg spectroscopy within the new optical system and report on progress towards observation of atommicrowave photon coupling. We also present theoretical calculations of Rydberg polarizability dressing to minimize the influence of background electric fields on the Rydberg states. [Preview Abstract] 

T01.00122: An atomic source of single photons in the telecom band Christopher Phenicie, Alan Dibos, Mouktik Raha, Jeff Thompson Single atoms are ideal sources of single photons and longlived memories for quantum networks. However, most atomic transitions are in ultravioletvisible wavelengths, where propagation losses in optical fibers prohibit long distance transmission. A notable exception is the Er$^{3+}$ ion, whose 1.5 $\mu$m transition is exploited in fiber amplifiers that drive telecommunication networks. However, an optical interface to single Er$^{3+}$ ions has not yet been achieved because of the low photon emission rate ($<$100Hz). Recently, we have observed the emission of single photons from a single Er$^{3+}$ ion in a solidstate host [1]. This was enabled by interfacing Er$^{3+}$ ions with silicon nanophotonic cavities, which enhances the photon emission rate by a factor of more than 300. Dozens of distinct ions can be addressed in a single device based on inhomogeneous variations in their transition frequencies. We will also discuss ongoing progress on characterizing the spin dynamics of this system, spinphoton entanglement, and interactions between nearby Er$^{3+}$ defects. These results are a significant step towards longdistance quantum networks and deterministic quantum logic for photons based on a scalable silicon nanophotonics architecture. [1] Dibos, A.M. et al, arxiv: 1711.10368 [Preview Abstract] 

T01.00123: Hybrid quantum interface for quantum transduction between mechanics and spins Jialun Luo, Hil Fung Harry Cheung, Yogesh S Patil, Mukund Vengalattore Diverse quantum systems are currently being developed for various aspects of quantum information processing, metrology and communication. A robust, coherent interface between such different systems is crucial to realize a quantum network. Here, we report progress on the quantum transduction between a mechanical resonator and quantum spins in a hybrid quantum system that optically interfaces a membraneinthemiddle optomechanical cavity with an ultracold spin ensemble. Such an implementation allows for a remote coupling between the two modular quantum systems. For system parameters realized in our laboratory, we show that the membrane resonator displacement can be transduced into spin excitations even at the level of the resonator zero point motion. As shown in recent theoretical work, this experimental demonstration of a coherent quantum interface is a powerful ingredient that can enable quantum state preparation, nonclassical state transfer and backactionevading measurements [1,2]. [1] F. Bariani, et al., Phys. Rev. A 92, 043817 (2015) [2] S. K. Steinke, et al., Phys Rev. A 84, 023841 (2011) [Preview Abstract] 

T01.00124: ContinuousVariable entanglement generation in a threewave mixing process Saeid Vashahri Ghamsari, Bing He, Min Xiao We have considered the threewave mixing process as a scheme for generating continuousvariable entanglement. In the undepleted pump approximation, the propagation of signal and idler waves in a waveguide is shown to be equivalent to two mixed modes propagating in two linear channels with equal loss and gain. Moreover, the phase mismatch between signal and idler waves plays the role of coupling between the two modes. Therefore, this system respects the PTsymmetry condition. On the other hand, a PTsymmetric system is a good candidate for generating "amplified" continuousvariable entanglement (macroscopic entanglement). If the signal and idler waves are prepared in the squeezed coherent state, the output fields are entangled. The virtue of this scheme is that, in contrast to traditional PTsymmetric systems, here the gain, loss, and coupling are parametric variables and hence one can control them by adjusting the amplitude and phase of the pump wave. In addition, the quantum noise effect in this parametric process is negligible. [Preview Abstract] 

T01.00125: A Hybrid NanophotonicMagnetic ChipBased Atom Trap Charles Fancher, Adam Black, Marcel Pruessner, Doewon Park, Dmitry Kozak, Rita Mahon, Mark Bashkansky, Fredrik Fatemi, Todd Stievater We report progress toward a chipbased cold atom trap using nanoscale subwavelength optical waveguides. Systems with subwavelengthscale optical structures, like optical nanofibers and photonic crystal cavities, exhibit enhanced coupling to emitters due to their confinement of electromagnetic modes in small areas and are of interest in quantum network applications and studies of collective atomlight interactions. Integrated rib waveguides similarly exhibit enhanced atomlight interactions, while also possessing the advantages of mechanical and thermal stability, flexibility in optical architecture design, and reliable lithographic fabrication. A principal challenge in experiments aimed at coupling atoms to fabricated nanophotonic waveguides is the efficient transfer of atoms to within hundreds of nm of the waveguide surface to reach the collective strongcoupling limit. In this work, we develop a hybrid approach to coupling atoms to the waveguide, by transferring $^{\mathrm{85}}$Rb atoms to the chip surface in a microscopic magnetic trap created by currentcarrying wire pairs centered on the optical waveguide. After installing a new, lower optical loss, atom chip we will begin experiments loading the optical waveguides. [Preview Abstract] 

T01.00126: A heavy impurity immersed in a BoseEinstein Condensate Zoe Yan, Yiqi Ni, Carsten Robens, Martin Zwierlein We report on the creation and study of Bose polarons using degenerate fermionic 40K atoms immersed in a BoseEinstein condensate (BEC) of 23Na. We observe the formation of the quasiparticles and measure their energy landscape via radiofrequency ejection spectroscopy. Besides measuring static properties such as polaron energy, we study collective oscillations between the majority BEC atoms and the impurities, demonstrating a strong locking of the two species' motion when their interaction strengths approach the unitary limit. Such measurements of polaron properties will inform work on a wide range of quantum phenomena, including highTc superconductivity and superfluid helium mixtures. [Preview Abstract] 

T01.00127: Optical Cycling of TlF Nathan Clayburn, Trevor Wright, David DeMille, Larry Hunter We investigated optical cycling of the X$^{\mathrm{1}}\Sigma ^{\mathrm{+}}$  B$^{\mathrm{3}}\Pi_{\mathrm{1}}$ transition in TlF by detection of the resulting fluorescence from laser excitation of a cryogenic molecular beam. The X(J$=$1) level of the ground state contains hyperfine and polarization dark states which decrease the photon cycling rate relative to that of a twolevel system. These dark states have been remixed into the optical cycling by rapid switching of the laser's polarization and by resonant microwave mixing with the X(J$=$0) level. The destabilization of these dark states has increased the measured cycling, and multiple rotational transitions remain promising for significant cycling. Additionally, external electric fields have been used to make Stark shift measurements from which the $\Omega $doublet of the excited state and the moleculefixed dipole moment of the excited state can be inferred. [Preview Abstract] 

T01.00128: Sculpting the spectral density of an atomic transition Logan W. Clark, Ningyuan Jia, Nathan Schine, Claire Baum, Jonathan Simon Floquet engineering enables atomic and optical systems to realize many interesting and otherwise inaccessible Hamiltonians. Here, we explore the use of a rapidly modulated AC Stark shift to dramatically modify the excitation spectrum of an atom. With this modulated driving we can split a single atomic line into multiple separate lines or convert an ordinary, Lorentzian line into an exotic new shape. One exciting application of this technique is to cavity QED experiments, where splitting one line into many enables a single atomic transition to be coupled with multiple modes of a nondegenerate cavity. We discuss experiments using this capability to explore collisions between stronglyinteracting cavity Rydberg polaritons in multiple transverse modes. [Preview Abstract] 

T01.00129: Probing manybody dynamics on a 51atom quantum simulator Harry Levine, Hannes Bernien, Alexander Keesling, Ahmed Omran, Hannes Pichler, Soonwon Choi, Sylvain Schwartz, Alexander Zibrov, Manuel Endres, Markus Greiner, Vladan Vuletic, Mikhail Lukin Controllable, coherent manybody quantum systems can provide insights into fundamental properties of quantum matter, enable the realization of exotic quantum phases, and ultimately offer a platform for computation that may surpass classical computing. Here we demonstrate a method for deterministically creating large, reconfigurable arrays of up to 51 individual cold atoms. We engineer strong, coherent interactions among the atoms by coupling them to highly excited Rydberg states. This allows us to realize a programmable Isingtype quantum spin model with a tunable range of interactions. Within this model, we experimentally study phase transitions into various spatially ordered states, and we observe universal scaling properties of these transitions as revealed by the KibbleZurek mechanism. Finally, we study manybody dynamics far from equilibrium, induced by a rapid change in system parameters. Our platform offers an opportunity to explore manybody physics on a programmable quantum simulator in a regime where exact classical simulation is intractable. [Preview Abstract] 

T01.00130: Topological superfluid in a BoseFermi mixture with spin exchangeinduced spinorbit coupling Chuanzhou Zhu, Li Chen, Hui Hu, XiaJi Liu, Han Pu We investigate the groundstate properties of a mixture of spin1/2 BoseEinstein condensate and spin1/2 Fermi superfluid. In our system, bosons are subjected to a pair of Raman laser beams that induces spinorbit coupling, while fermions are not coupled to the Raman laser. We show that the fermions can acquire an effective spinorbit coupling from the spinexchange interaction between bosons and fermions. In the regime where the boson number is more than the fermion number, we study the topological phase transition of the Fermi superfluid by monitoring the close and reopen of the energy gap, the Berry phase, and the superfluid order parameter, where the backaction to the Bose condensate is also taken into consideration. Our work provides a new way of achieve topological Fermi superfluid. [Preview Abstract] 

T01.00131: Angular Momentum of a BoseEinstein Condensate in a Synthetic Rotational Field Chunlei Qu, Sandro Stringari By applying a positiondependent detuning to a spinorbitcoupled Hamiltonian with equal Rashba and Dresselhaus coupling, we exploit the behavior of the angular momentum of a harmonically trapped BoseEinstein condensed atomic gas and discuss the distinctive role of its canonical and spin components. By developing the formalism of spinor hydrodynamics we predict the precession of the dipole oscillation caused by the synthetic rotational field, in analogy with the precession of the Foucault pendulum, the excitation of the scissors mode, following the sudden switching off of the detuning, and the occurrence of Halllike effects. When the detuning exceeds a critical value we observe a transition from a vortex free, rigidly rotating quantum gas to a gas containing vortices with negative circulation which results in a significant reduction of the total angular momentum. [Preview Abstract] 

T01.00132: Local Measurements of the Topological Invariants of a Quantum Hall System Nathan Schine, Michelle Chalupnik, Tankut Can, Andrey Gromov, Jonathan Simon Nontrivial topology undergirds a multitude of intriguing phenomena in condensed matter and AMO physics. A single topological invariant may be appear in multiple apparently unrelated observablesfor instance, in integer quantum Hall systems, the Chern number appears in the bulk transverse (Hall) conductivity, the presence of robust chiral edge modes, the transport of quantized charge, and more, each of which teaches us about the physical implications of topology. Generic quantum Hall materials support two additional topological invariants, the mean orbital spin and central charge. We describe and perform local, realspace measurements of all three invariants in photonic Landau levels. The techniques used are compatible with strong interactions provided by cavity Rydberg electromagnetically induced transparency, and offer new perspectives for the characterization of exotic topological materials. [Preview Abstract] 

T01.00133: Floquet engineering in interacting systems of ultracold Fermions in optical lattices Kilian Sandholzer, Frederik G\"org, Michael Messer, Joaquin Minguzzi, Gregor Jotzu, Remi Desbuquois, Tilman Esslinger Periodic modulation is a powerful tool to modify properties of a static system such as opening topological gaps or controlling magnetic order. The versatility of cold atom experiments offers the possibility to implement many of these schemes. Nonetheless, preparing a desired Floquet state in this outofequilibrium situation is a more difficult task, especially when the driving frequency is close to a characteristic energy scale of the system. In this work, we prepare fermionic atoms in a driven optical lattice such that the system can be described by two interacting particles on a double well potential with a periodically modulated tilt. We show how to adiabatically prepare and control individual Floquet states. This study is extended to a 3D connected lattice, implementing a driven FermiHubbard model. In the offresonant case the dynamics of the manybody system can be understood by an effective Hamiltonian which is experimentally observed by directly comparing the driven system to its static counterpart. [Preview Abstract] 

T01.00134: Twodimensional optical quasicrystal potentials for ultracold atom experiments Theodore A. Corcovilos Quasicrystals are nonperiodic arrangements of atoms having no translational symmetry but nonetheless possess longrange order. The mechanical, thermal, and electronic properties of quasicrystals, specifically their lowtemperature behavior, defy easy description because of the difficulty in creating defectfree samples and the difficulty of simulating nonperiodic geometries. Quantum simulation using analogous systems such as ultracold atoms in optical lattice potentials provides an efficient investigative tool. We present a realistic optical design using nearly copropagating beams that generates a 2D quasicrystal potential with 10fold symmetry. This geometry allows more control of the optical lattice geometry than the more common method of using coplanar beams and is easier to align. We also can generate phason excitations and quantized transport in the quasicrystal through phase modulation of the beams, giving us a direct route to study the topological properties of twodimensional quasicrystals. Numerical simulation results of the optical system, including diffraction effects, and preliminary experimental data on the optics system will be presented. [Preview Abstract] 

T01.00135: New cooling schemes for creating ultralow entropy states of fermions in optical lattices Christie Chiu, Geoffrey Ji, Anton Mazurenko, Muqing Xu, Daniel Greif, Markus Greiner Ultracold fermions in optical lattices are a powerful platform for addressing open questions on strongly correlated quantum phases. The readout and control afforded by quantum gas microscopy offers a unique insight into such systems and a deep understanding of the microscopic mechanisms at play. In our experiment, we use a digital mirror device to control the potential landscape of individual atoms. We shape the underlying confinement potential and create nearperfect band insulators of doublons containing more than 250 particles. We then use this band insulator as a starting point for a scheme based on adiabatic state preparation: we continuously change the Hamiltonian by controlling site offsets on individual sites to transform the manybody state into an antiferromagnet at halffilling. In the final state we detect strong antiferromagnetic correlations and find the temperature to be below the magnetic exchange energy. We study the applicability of this scheme to various system sizes and initial configurations, including doublewells, spin ladders as well as regular 1D and 2D lattices. This new cooling method potentially allows realizing temperatures in the future where a superconducting state is expected in the Hubbard model. [Preview Abstract] 
(Author Not Attending)

T01.00136: Probing topological superfluidity in a system of repulsive alkalineearth atoms in optical lattices Gerardo Ortiz, Leonid Isaev, Adam Kaufman, Ana Maria Rey Topological superfluids are of technological relevance since they are believed to host Majorana bound states, a powerful resource for quantum computation and memory. I will describe an experimentally feasible realization of topological superfluidity with fermionic atoms in an optical lattice. We consider a situation where atoms in two internal states experience different lattice potentials: one species is localized and the other itinerant, and show how quantum fluctuations of the localized fermions give rise to an attraction and strong spinorbit coupling in the itinerant band. At low temperature, these effects stabilize a topological superfluid of mobile atoms even if their bare interactions are repulsive. This emergent state can be engineered with ${}^{87}$Sr atoms in a superlattice with a dimerized unit cell. To probe its unique properties we describe protocols that use high spectral resolution and controllability of the Sr clock transition, such as momentumresolved spectroscopy and emergent magnetoelectric phenomena when the system exhibits a supercurrent response to a synthetic (laserinduced) magnetic field. [Preview Abstract] 

T01.00137: Few body bound states in a lattice Jugal Talukdar, D. Blume The addition of a lattice greatly modifies the properties of fewbody bound states in free space. The presence of a lattice does, in general, introduce a dependence of the bound state energy on the total lattice or quasimomentum. Interestingly, two particles may form a bound state in the lattice even if the interaction between the particles is repulsive. This contribution reports on our theoretical progress on characterizing two and threebody bound states in a lattice. [Preview Abstract] 

T01.00138: Metastability and avalanche dynamics in stronglycorrelated gases with longrange interactions Lorenz Hruby, Nishant Dogra, Katrin Kroeger, Manuele Landini, Tobias Donner, Tilman Esslinger We experimentally study metastable behavior of a Mottinsulator (MI) and a charge density wave (CDW) in an extended BoseHubbard model with globalrange interactions. The model is realized by loading a degenerate 87Rb Bose gas into a threedimensional optical lattice. The globalrange interactions are mediated by photons offresonantly scattered from a lattice beam  off the quantum gas  into an optical cavity mode. Initializing the system in an MI state, we rapidly increase the strength of globalrange interactions  by changing the detuning from the cavity  to different final values. By monitoring the photon flux leaking from the cavity in realtime and extracting from it the amount of density modulation (imbalance), we observe that the system falls into either of two distinct final states. In additional experiments, we observe hysteresis between the two states and an avalanche tunneling dynamics. [Preview Abstract] 

T01.00139: Stability of Bose Einstein Condensates in Periodically Driven 2D Optical Lattices James Maslek, Thomas Boulier, Carlos Bracamontes, Eric Magnan, Trey Porto Periodically driven quantum systems offer new possibilities to Floquetengineer nontrivial Hamiltonians displaying exotic properties. One drawback to periodic driving is the transfer of energy from the drive to the system, resulting in heating. A detailed understanding of the underlying manybody mechanisms is necessary for quantum Floquet engineering to mature as a powerful coherent control scheme. So far, such studies are few and focus on unidimensional drives in 1D lattices. We measured heating rates for bosons subject to a bidirectional drive of arbitrary trajectory imposed onto 2D and 3D optical lattices. We report how the heating depends on the frequency, intensity, and the trajectory of the drive. Dynamical instabilities cannot be ignored for higherdimensional driving, due to a band inversion at certain driving strengths. This results in an increased rate of decay, and imposes constraints on the initial momenta at a given drive. We thus provide a map of timescales available for coherent control throughout the parameter space, along with an understanding of the manybody quantum processes involved. [Preview Abstract] 

T01.00140: Observation of Spin Transport in the 2D FermiHubbard Model Matthew Nichols, Melih Okan, Lawrence Cheuk, Enrique Mendez, Thomas Hartke, Hao Zhang, Ehsan Khatami, Martin Zwierlein In solid state systems, a plethora of interesting phenomena manifest themselves in the transport properties of a material. Several prototypical examples include the quantum hall effect, superconductivity, and giant magnetoresistance. With this in mind, an indepth exploration of the transport properties of the 2D FermiHubbard model, a model which is believed to capture the essential aspects of hightemperature superconductivity in the cuprates, is worth pursuing. In this poster, using a quantum gas microscope which allows for singlesite readout, we study spin transport in such a system. By applying a magnetic field gradient to a homogeneous sample of ultracold $^{\mathrm{40}}$K atoms trapped in a square optical lattice, we examine how the system evolves in real time under a spindependent perturbation. For a halffilled system in the Mottinsulating regime, we observe spin dynamics which are diffusive in nature. This allows us to extract both the spin diffusion coefficient and the spin conductivity as functions of the Hubbard parameters. These findings are compared with novel numerical linkedcluster expansion (NLCE) calculations. [Preview Abstract] 

T01.00141: Optical lattices with periodicity well below $\lambda $/2 Sarthak Subhankar, Yang Wang, TszChun Tsui, James V. Porto, Steven Rolston Optical potentials based on the acStark shift are used extensively in the investigation of lattice models of quantum many body systems. But these potentials are limited by diffraction to have a lattice constant no less than $\lambda $/2, where $\lambda $ is the wavelength of light used. This sets a temperature scale in these lattices given by T\textasciitilde E$_{\mathrm{R}}$/k$_{\mathrm{B}}$ , where E$_{\mathrm{R}}=$h$^{\mathrm{2}}$/8md$^{\mathrm{2\thinspace \thinspace }}$and d is the lattice constant. Study of phenomena like superexchange and magnetic dipole interactions require much lower temperatures than that set by E$_{\mathrm{R}}$. By engineering lattices with subwavelength lattice constants, the temperature requirements to study these phenomena can be relaxed. Recently, we have demonstrated an optical lattice based on dark states with subwavelength barriers of width $\lambda $/50 [1]. By stroboscopically dithering the phase of this lattice while remaining in a dark state, a timeaveraged potential with subwavelength lattice spacing of $\lambda $/(2N) can be realized [2]. Here we report our progress on the realization of such a lattice. [1] arXiv:1712.00655 [2] Phys. Rev. Lett. 115, 140401 [Preview Abstract] 

T01.00142: Performance of Atomic EnsembleCavity System for LongDistance Entanglement Distribution Kevin Cox, David Meyer, Paul Kunz A quantum repeater will be necessary for longdistance (\textgreater 1000 km) quantum communication, and much progress has been made towards realizing such a device. Neutral atomic ensembles have shown particular promise as a repeater platform due their strength in terms of lightmatter interface efficiency and coherence lifetimes. One remaining challenge is to improve the entanglement distribution rate between remotely located nodes. This rate has been primarily limited by the small probability for successfully writing to the relevant quantum memory mode, which must be kept low to avoid increased error rates. By spatially multiplexing the quantum memory this limitation can be alleviated. We are developing an atomcavity system that simultaneously achieves stateoftheart performance for quantum memory efficiency (i.e. photon collection efficiency \textgreater 90{\%}) and enables a high degree of spatial multiplexing (number of spatial modes N \textgreater 100). Such a system can improve the entanglement distribution rate by more than a factor of N, and significantly reduce the requirements on memory lifetime. With these improvements a quantum repeater becomes realistically achievable in the near term. [Preview Abstract] 

T01.00143: Experimental demonstration of superadiabatic quantum friction suppression in finitetime thermodynamics Aurelia Chenu, Shujin Deng, Pengpeng Diao, Fang Li, Shi Yu, Ivan Coulamy, Adolfo del Campo, Haibin Wu Optimal performance of thermal machines is reached by suppressing friction, which in quantum thermodynamics results from fast driving schemes that generate nonadiabatic excitations. The farfromequilibrium dynamics of quantum devices can be tailored by shortcuts to adiabaticity (STA) to suppress quantum friction, that provide a disruptive approach and allow operating at maximum efficiency with arbitrarily high output power. We experimentally demonstrate the suppression of quantum friction in the finitetime thermodynamics of a stronglyinteracting quantum fluid, by implementing frictionfree superadiabatic strokes with a unitary Fermi gas in an anisotropic timedependent trap as a working medium. The control is achieved using STA that exploit the emergent scaleinvariance in the unitary regime. We further establish the equivalence between the superadiabatic mean work and its adiabatic value. The enhancement of the mean work output is thus demonstrated in superadiabatic strokes. Combined with cooling and heating steps, superadiabatic strokes can be used to engineer frictionfree scalable quantum thermal devices that operate at maximum efficiency with high output power, opening new routes with applications at the interface of quantum thermodynamics and energy science. [Preview Abstract] 

T01.00144: Low Noise Laser System for Atom Interferometer Applications Azure Hansen, YunJhih Chen, Gregory W. Hoth, Eugene Ivanov, John Kitching, Elizabeth A. Donley We present a low noise, robust, and flexible laser system that simplifies atom interferometer experiments for applications in remote sensing and navigation. We use one externalcavity diode laser (ECDL) and one frequencydoubled telecom laser, both with linewidths $<100\,$kHz. The telecom laser is locked to the ECDL with an optical phase lock loop (OPLL), which electronically shifts the telecom laser’s frequency for different stages of the experiment. The OPLL moves the laser frequency by hundreds of MHz and the frequency stabilizes within a few hundred $\mu$s. While we demonstrate this laser system on a compact point source atom interferometer gyroscope, the technique is of interest for other experiments requiring many different nonconcurrent frequencies. [Preview Abstract] 

T01.00145: Bichromatic slower for inertial sensing using slow atoms Chao Li, Xiao Chai, Chandra Raman We present progress toward an atom interferometer (AI) inertial sensor utilizing a slow rubidium atomic beam. Bichromatic forces decelerate the atoms to tens of meters/second using two counterpropagating light fields. The use of stimulated forces provides a substantial reduction in the deceleration distance, and therefore, the overall system size, compared with traditional laser cooling using spontaneous forces (for example, Zeeman slowers). Slow atoms possess distinct advantages for portable sensors aimed at dynamic platforms, as their sensitivity can be comparable to MOT based atom interferometer experiments operated at high data rates, but without suffering from dead time associated with trap loading. [Preview Abstract] 

T01.00146: Modeling degenerate pulsed electron matter waves with partial quantum coherence Sam Keramati, Eric Jones, Herman Batelaan With the advent of femtosecond laserdriven nanotip electron sources, degenerate electron beams now seem to be within reach. Electron beam degeneracy is characterized by electron antibunching; the signature of the fermionic Hanbury BrownTwiss effect. The strength of the observed antibunching signal in an electron coincidence experiment is determined by the combined effects of the source polarization and the degree of quantum coherence of the beam. Low quantum coherences will lead to miniscule antibunching signals similar to the case reported in reference [1] with an unpolarized CW electron source. Such tiny signals are not differentiable from the effect of Coulomb repulsion of neighboring electrons [2]. Thus, to observe the Hanbury BrownTwiss effect unambiguously, the degree of quantum coherence must not be too small, as afforded by nanotip sources. In this work, we model quantum partial coherence in two different ways. In the first approach we propagate a mixed state using the Feynman path integral technique. In the second approach, quantum decoherence theory is used to obtain a partially coherent twoelectron state by tracing over environmental states. [1] H. Kiesel, et al., Nature 418, 392 (2002) [2] G. Baym, et al., arXiv: 1212.4008 (2012) [Preview Abstract] 

T01.00147: Low power laserdriven electron source based on plasmon enhanced metalized optical fiber tips Sam Keramati, Ali Passian, Vineet Khullar, Pavel Lougovski, Herman Batelaan Pulsed laserdriven electron sources have been extensively studied and developed over the past decade to achieve coherent pulsed electron matter waves. The electrons are generated by focusing femtosecond laser pulses on metallic nanotips. Applications range from electron microscopy to the study of fundamental quantum mechanical processes [1]. It is therefore advantageous to replace femtosecond lasers with the much simpler diode lasers. We demonstrate that metalized optical fiber tips can emit electrons by diode laser illumination. We present our experimental data after the theoretical analysis of the problem [2] along with the simulation results of the proposed plasmon assisted electron emission. The laser beam is coupled into the uncoated end of the optical fiber allowing the light to propagate to the metalized fiber tip. No further optical alignment is required within the vacuum system. The electrons from the tip can thus be conveniently delivered anywhere in a vacuum chamber. This heralds a prospective lowcost plugandplay electron source. The detailed wavelength dependence of the emission will be used to investigate the proposed plasmonbased mechanism. [1] B. Barwick, et al, New J Phys 9, 142 (2007) [2] A. Passian, et al, Phys Rev B 71, 115425 (2005) [Preview Abstract] 

T01.00148: Conditional phase shift between single photon pulses with different velocities in a Kerr medium Balakrishnan Viswanathan, Julio GeaBanacloche Spectral entanglement is a potentially significant obstacle to the eventual realization of quantum logical gates at the singlephoton level using optical nonlinearities \footnote{J GeaBanacloche, Phys. Rev. A \textbf{81}, 043823 (2010)}. It has recently been pointed out \footnote{D. J. Brod, J. Combes, and J. GeaBanacloche, Phys. Rev. A \textbf{94}, 023833 (2016)} that this unwanted effect can be virtually eliminated by setting up a situation where conservation of momentum and energy lead to nonequivalent algebraic conditions on the wavevectors and frequencies of the interacting photons. We verify that this may be the case, in principle, for two photons traveling through a nonlocal Kerr medium with different velocities (co or counterpropagating). The role of the nonlocality is merely to make the theory well behaved, and is essentially equivalent to a truncation of the medium's bandwidth, as we also verify here. [Preview Abstract] 

T01.00149: Room temperature highfidelity nonadiabatic holonomic quantum computation on solidstate spins in NitrogenVacancy centers Guoan Yan, Hua Lu, AiXi Chen The highspeed implementation and robustness against of nonadiabatic holonomic quantum computation provide a new idea for overcoming the difficulty of quantum system interacting with the environment easily decoherence, which realizes largescale quantum computer construction. Here, we show that a highfidelity quantum gates to implement nonadiabatic holonomic quantum computation under solidstate spin in NitrogenVacancy(NV) centers, providing an extensible experimental platform that has the potential for roomtemperature quantum computing, which has increased attention recent years. Compared with the previous method, we can implement both the one and twoqubit gates by varying the amplitude and phase of the microwave pulse applied to control the nonAbelian geometric phase acquired by NV centers. We also find that our proposed scheme may be implemented in the current experiment to discuss the gate fidelity with the experimental parameters. Therefore, the scheme adopts a new method to achieve highfidelity nonadiabatic holonomic quantum computation. [Preview Abstract] 

T01.00150: Generation of Tunable Frequency Combs for CavityEnhanced Ultrafast Spectroscopy Myles C. Silfies, Yuning Chen, Henry Timmers, Abijith S. Kowligy, Alex Lind, Scott A. Diddams, Thomas K. Allison Through the use of a frequency comb laser and optical enhancement cavities, we have previously demonstrated a detection limit of $\Delta$OD $= 1 \times 10^{9}/\sqrt{\textrm{Hz}}$ in a time resolved measurement on a dilute molecular beam. However, in order to have a more widely applicable spectrometer, the pump and probe wavelengths must be tunable. Here we present a frequency conversion setup for the generation of high average power frequency combs across the ultraviolet, visible, and infrared. The initial comb is generated using an Er:fiber oscillator at 100 MHz which, after nonlinear amplification, is shifted in a highly nonlinear fiber to 1 $\mu$m and amplified to 10W in a home built Yb:fiber amplifier. This light is then used as a pump for several nonlinear processes including a dualfocus optical parametric oscillator for the generation of tunable visible frequency combs from 450 to 700 nm. Optical parametric amplifiers are used for infrared comb generation from 3 to 5 $\mu$m which are seeded by additional shifted erbium comb branches. [Preview Abstract] 

T01.00151: Telecom and Rubidium Resonant Single Photons from a Barium Ion Via Quantum Frequency Conversion John Hannegan, James Siverns, Qudsia Quraishi Trapped ions typically emit short wavelength photons with limited propagation range due to substantial attenuation in optical fibers. To extend the transmission range of photons from trapped Ba$^{\mathrm{+}}$ ions, quantum frequency conversion (QFC) in a nonlinear crystal allows for translation of the ion's native wavelength to a more desirable wavelength. The conversion is performed in a periodically poled lithium niobate waveguide via difference frequency generation between the ion's photon and a high intensity pump. Ba$^{\mathrm{+}}$ has two strong optical dipole transitions which produce visible photons at 650 nm and 493 nm. Here, we show single stage conversion of 650 nm Ba$^{\mathrm{+}}$ resonant laser light to the telecom OBand (1259 nm). We also show single stage conversion of single 493 nm photons from a $^{\mathrm{138}}$Ba$^{\mathrm{+}}$ ion to 780 nm and, via measurement with a wavemeter, confirm its resonance with $^{\mathrm{87}}$Rb [1]. Finally, we show twostage conversion of single 493 nm photons to the telecom CBand near 1550 nm. We discuss the tunability and optimization of the conversion setup, as well as signaltonoise at the single photon level. These results, as well as QFC results using Ca$^{\mathrm{+}}$ [2,3] provides a pathway for remote interion quantum networking and possible hybrid networking. [1] J.D. Siverns, J. Hannegan, Q. Quraishi, arXiv:1801.01193 (2018) [2] T. Walker, et. al., arXiv:1711.09644 (2017) [3] M. Bock, et. al., arXiv:1710.04866 (2017) [Preview Abstract] 

T01.00152: Developing convenient fiber and solid state laser sources for use in atomic physics Ali Khademian, Ronnie Currey, Matthew Truscott, David Shiner The evolution of rareearth 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 fibers. We have been interested in developing Thulium (Tm) doped fiber lasers designed for operation at 2058 nm and Ytterbium (Yt) doped fiber lasers at 1083 nm for studying the helium atom. Fiber lasers are typically pumped by very reliable and low cost high power fiber coupled solid state lasers operating at 920, 975 and 793 nm. 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 the current status of our 2058 nm source made of Tm fiber with an output power of 2 W, which is used for quenching singlet helium atoms in our apparatus. Nonlinear wavelength conversion also provides us the opportunity to develop custom laser sources that cover spectral regions otherwise not readily available. We will discuss the current status of a single frequency blue laser at 486 nm with output power of 500 mW by second harmonic generation (SHG) from IR. This laser also could be used as a fundamental laser source for an additional SHG stage to generate UV such as 243 nm for study of hydrogen like atoms. We will discuss our approaches for using a number of BBO crystals in series which are bounded by adhesive free technology. This improves the conversion efficiency as well as beam quality of the generated UV at 243 nm. [Preview Abstract] 

T01.00153: Fourwave Mixing in Hot Sodium Vapor Cells Qimin Zhang, Saesun Kim, Logan Narcomey, Alberto Marino, Arne Schwettmann Squeezed states of light have a wide range of applications in quantumenhanced sensing, quantum information processing, and other quantum technologies. It has been shown that nondegenerate fourwave mixing (4WM) in a hot atomic vapor cell can be used to produce quantum correlated twin beams of light. In a 4WM process, two pump photons are absorbed and produce two correlated twin photons, called probe and conjugate. Many 4WM experiments have been done in Rb to generate quantum squeezed states of light. 4WM using Na is expected to be more difficult due to the smaller hyperfine splitting compared to Rb: 1.77 GHz for $^{23}$Na and 3.04 GHz for $^{85}$Rb. For Na in a hot atomic vapor, this causes the Dopplerbroadened transitions between the ground states and the first excited states to overlap. We present our experimental progress towards 4WM in a double$\Lambda$ configuration on the Dopplerbroadened D2 line of $^{23}$Na. We characterize the dependences of the 4WM gain on the pump and the probe frequencies, intensities, and the angle between the pump and the probe beams. We also compare our experimental results with a semiclassical model by calculating the susceptibilities and solving the classical propagation equation for the twinbeam fields. [Preview Abstract] 

T01.00154: Highmomentum tail and universal relations of a Fermi gas near a Ramandressed Feshbach resonance Fang Qin, Jianwen Jie, Wei Yi, GuangCan Guo In a recent proposal [Jie and Zhang, Phys. Rev. A 95, 060701(R) (2017)], it has been shown that centerofmassmomentumdependent twobody interactions can be generated and tuned by Ramancoupling the closedchannel bound states in a magnetic Feshbach resonance. Here we investigate the universal relations in a threedimensional Fermi gas near such a laser modulated $s$wave Feshbach resonance. Using the operatorproduct expansion approach, we find that, to fully describe the highmomentum tail of the density distribution up to $q^{6}$ ($q$ is the relative momentum), four centerofmassmomentumdependent parameters are required, which we identify as contacts. These contacts appear in various universal relations connecting microscopic and thermodynamic properties. Particularly, we find that the $q^{5}$ tail and part of $q^{6}$ tail of the momentum distribution show anisotropic features. We derive the universal relations, and, as a concrete example, estimate the contacts for the zerotemperature superfluid ground state of the system using a meanfield approach. [Preview Abstract] 

T01.00155: Optimal control for highprecision atom interferometry Michael Goerz, Mark Kasevich, Vladimir Malinovsky Recent advances in atomic interferometry open up new pathways to high precision measurements, as well as tests of general relativity, and new gravitational wave detectors. The fundamental limitation in an atomic fountain interferometer is the realization of highfidelity, robust atom beamsplitters and mirrors. These must be realized through carefully tuned laser pulses manipulating the atomic momentum states. We present avenues for the use of numerical optimal control theory (OCT) to design suitable pulse sequences. OCT has been shown to be a powerful tool in a wide range of design tasks, allowing to steer a quantum system towards a desired goal in the shortest possible amount of time. It also allows to maximize the robustness against dominant sources of noise, and can be targeted to the specific parameters of an experimental setup. Our scheme for the realization of an atomic mirror relies on using frequencychirped standing waves and rapid adiabatic passage. Using a combination of control techniques, we show how an analytical pulse scheme can be compressed by more than an order of magnitude, while also bringing nonadiabatic errors arbitrarily close to zero. We will discuss how the resulting scheme may also be made robust with respect to both quantum and classical noise sources. [Preview Abstract] 

T01.00156: Toward a determination of the protontoelectron mass ratio from a Lambdip measurement of HD S.M. Hu, L.G. Tao, A.W. Liu, Y. R. Sun, J. Wang, J. Komasa, K. Pachucki Precision spectroscopy of the hydrogen molecule is a test ground of quantum electrodynamics (QED), and may serve for determination of fundamental constants. Using a comblocked cavity ringdown spectrometer, for the first time, we observed the Lambdip spectrum of the R(1) line in the overtone of HD. The line position was determined to be 217 105 182.79(9) MHz ($\delta\nu /\nu = 4\times 10^{10}$), which is the most accurate rovibrational transition ever measured in the ground electronic state of molecular hydrogen. Moreover, from calculations including QED effects up to the order $m_e\alpha^6$, we obtained predictions for this R(1) line as well as for the HD dissociation energy, which are less accurate but signaling the importance of the complete treatment of nonadiabatic effects. Provided that the theoretical calculation reaches the same accuracy, the present measurement will lead to a determination of the protontoelectron mass ratio with a precision of 1.3 parts per billion. [Preview Abstract] 

T01.00157: Precision laser spectroscopy of the $2^3S2^3P$ transition of $^4$He Xin Zheng, Yu Robert Sun, Jiaojiao Chen, Shuiming Hu The finestructure splitting of the $2^3P_J$ levels of $^4$He is of great interest for tests of quantum electrodynamics and for the determination of the fine structure constant $\alpha$. The $2^3S2^3P$ transition absolute frequency, when combined with the pointlike nucleus theoretical calculations, may provide accurate determination of the helium nuclear charge radius. Here we report our recent studies on the finestructure splitting intervals, as well as the absolute frequency of the $2^3S2^3P$ transitions. Laser spectroscopy was performed via $2^3P_J2^3S_1$ transitions at 1083nm. The $2^3P_02^3P_2$ and $2^3P_12^3P_2$ intervals were determined to be 31 908 130.98(13) kHz and 2 291 177.56(19) kHz, respectively. Both intervals showed good agreements with the latest theoretical calculations. The absolute frequency of the $2^3S2^3P$ centroid transition was measured with a relative accuracy of $5\times10^{12}$. [Preview Abstract] 

T01.00158: Highprecision measurements and theoretical calculations of indium excitedstate polarizabilities Daniel Maser, Bingyi Wang, Nathaniel Vilas, Priyanka Rupasinghe, Marianna Safronova, Ulyana Safronova, Protik Majumder Recent measurements in our group of indium scalar polarizability within two lowlying transitions showed excellent agreement with \textit{ab initio} atomic theory at the $12\%$ level. We have completed measurements of the polarizability within the $6s_{1/2} \rightarrow 7p_{1/2,3/2}$ excitedstate transitions. In our experiment, two external cavity semiconductor diode lasers interact transversely with a collimated indium atomic beam. We tune a 410 nm laser to the $5p_{1/2} \rightarrow 6s_{1/2}$ transition, keeping the laser locked to the exact Starkshifted resonance frequency. We overlap a second (685 or 690 nm) laser to reach the $7p$ excited states, using lockin detection to observe its very small absorption in the atomic beam. Monitoring the twostep excitation signal in a fieldfree supplemental vapor cell provides frequency reference and calibration. Scalar polarizabilities for the $7p$ states are 12 orders of magnitude larger than in previously measured transitions, so that application of modest, precisely calibrated electric fields of a few kV/cm produce Stark shifts of order 100 MHz. We also extracted the tensor polarizability of the $7p_{3/2}$ state by applying fields of roughly 15 kV/cm. Experimental details, results, and theoretical comparisons will be presented. [Preview Abstract] 

T01.00159: Ultrastronglycoupled Polariton Enhanced THG : Experiment and Theory Michael Crescimanno, Bin Liu, Samuel Schwab, Kenneth Singer Recent experimental results on enhanced third harmonic generation (THG) from ultrastronglycoupled polaritons are reported and used to test the theoretical understanding of this process in complex organic nonlinear optical materials and geometries at very large coupling. In contrast to other studies which pump these systems on the polaritons, we measure and model THG output at wavelengths corresponding to the polariton resonances. [Preview Abstract] 

T01.00160: A new approach to calculations of the hyperfine structure with empiricallydeduced nuclear and quantum electrodynamic effects Jacinda Ginges, Andrey Volotka Calculations of the magnetic hyperfine structure rely on the input of nuclear properties  nuclear magnetic moments and nuclear magnetization distributions  as well as quantum electrodynamic (QED) radiative corrections for highaccuracy evaluation in heavy atoms. The uncertainties associated with assumed values of these properties limit the accuracy of atomic calculations. We propose a method for removing this dependence by using measurements and calculations of the hyperfine structure for high states. We have demonstrated removal of the nuclear dependence for $s$, $p_{1/2}$, and $p_{3/2}$ states of Cs, Fr, Ba$^+$, and Ra$^+$. Furthermore, we have shown that for $s$ states the dependence on QED effects may also be removed. This method allows the atomic wave functions in the nuclear vicinity to be tested with increased accuracy and is important for atomic parity violation studies. [Preview Abstract] 

T01.00161: Towards lattice spin models with Rydbergdressed cesium atoms Ognjen Markovic, Victoria Borish, Jacob Hines, Monika SchleierSmith Rydbergdressed atoms provide a versatile platform to engineer lattice spin models for studies of frustrated magnetism and quantum manybody dynamics. In our experiment, cesium atoms will be pinned in a bluedetuned twodimensional optical lattice with a spacing continuously variable over 15 µm. A 320 nm laser couples groundstate cesium atoms to nP Rydberg states with a single photon, enabling highly coherent and tunable interactions. We report on progress in preparing the atomic system, including optically transporting atoms with actively stabilized focustunable lenses from a magnetooptical trap to the optical lattice. Here, the large interatomic spacings and close optical access will facilitate singlespinresolved imaging for detailed characterization of manybody quantum states. [Preview Abstract] 

T01.00162: QED corrections to E1 amplitudes in heavy and superheavy atoms and ions Jacinda Ginges, Joel Brown We use the radiative potential method to perform a detailed study of quantum electrodynamic (QED) radiative corrections to electric dipole (E1) transition amplitudes in heavy and superheavy alkalimetal atoms Rb, Cs, Fr, E119 and alkalimetallike ions Sr$^+$, Ba$^+$, Ra$^+$, and E120$^+$. The validity of the method is checked by comparing with the results of rigorous QED in the same atomic potential. We study the effects of core relaxation, polarization of the core by the E1 field, and valencecore correlations. [Preview Abstract] 

T01.00163: Calculations of the groundstate hyperfine structure for Rb, Cs, Fr, Ba$^+$, and Ra$^+$ Jacinda Ginges, Andrey Volotka, Stephan Fritzsche We have performed a comprehensive and highaccuracy study of the groundstate hyperfine structure for heavy alkalimetal atoms Rb, Cs, Fr and alkalimetallike ions Ba$^+$ and Ra$^+$ of interest for atomic parity violation studies. We have rigorously evaluated the quantum electrodynamic radiative corrections at oneloop level and have carefully considered the effect due to the magnetization distribution of the nucleus. Manybody calculations in the allorders correlation potential method were performed. [Preview Abstract] 

T01.00164: KeldyshRutherford model for attoclock Alexander Bray, Sebastian Eckart, Anatoli Kheifets We demonstrate a clear similarity between attoclock offset angles and Rutherford scattering angles taking the Keldysh tunnelling width as the impact parameter and the vector potential of the driving pulse as the asymptotic velocity. This simple model is tested against the solution of the timedependent Schr\"odinger equation using hydrogenic and screened (Yukawa) potentials of equal binding energy. We observe a smooth transition from a hydrogenic to ‘hardzero’ intensity dependence of the offset angle with variation of the Yukawa screening parameter. Additionally we make comparison with the attoclock offset angles for various noble gases obtained with the classicaltrajectory Monte Carlo method. In all cases we find a close correspondence between the model predictions and numerical calculations. This suggests a largely Coulombic origin of the attoclock offset angle and casts further doubt on its interpretation in terms of a finite tunnelling time. [Preview Abstract] 
Follow Us 
Engage
Become an APS Member 
My APS
Renew Membership 
Information for 
About APSThe American Physical Society (APS) is a nonprofit membership organization working to advance the knowledge of physics. 
© 2021 American Physical Society
 All rights reserved  Terms of Use
 Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 207403844
(301) 2093200
Editorial Office
1 Research Road, Ridge, NY 119612701
(631) 5914000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 200452001
(202) 6628700