Bulletin of the American Physical Society
APS March Meeting 2016
Volume 61, Number 2
Monday–Friday, March 14–18, 2016; Baltimore, Maryland
Session L50: Cold Atomic Gases: Precision Measurement and FewBody Physics 
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Sponsoring Units: DAMOP Chair: Shina Tan, Georgia Institute of Technology Room: Hilton Baltimore Holiday Ballroom 1 

L50.00001: ABSTRACT WITHDRAWN 
Wednesday, March 16, 2016 11:27AM  11:39AM 
L50.00002: Atom interferometric measurement of ``Big G'' on the International Space Station Elizabeth Ashwood, Doga Murat Kurkcuoglu, Mark Edwards, Charles Clark Recent measurements of Newton's universal gravitational constant (``Big G'') using atom interferometric methods have increased the uncertainty in the value of this important fundamental constant\footnote{See, e.g., S.\ Schlamminger, {\em Nature} {\bf 510}, 478 (2014)}. We have developed tools for rapid simulation and evaluation of atom interferometer (AI) schemes that can be implemented in the Cold Atom Laboratory to be deployed to the International Space Station (ISS) in 2017. We have approximated the solution of the rotatingframe GrossPitaevskii equation in both one and three dimensions by using the Lagrangian Variational Method (LVM). The LVM trial wave function is a sum of $N_{c}$ Gaussian clouds and we have derived equations of motion for the centers, widths, and phase parameters of these clouds. These equations of motion can be rapidly solved for many different AI designs enabling the estimation of interferometer sensitivity and the effects of errors. We present two potential schemes for measuring ``Big G'' on the ISS. These include a MachZehnderlike scheme as well as a design similar to a Foucault Pendulum. [Preview Abstract] 
Wednesday, March 16, 2016 11:39AM  11:51AM 
L50.00003: Sensitivity improvements to the YbF electron electric dipole moment experiment Isabel Rabey, Jack Devlin, Ben Sauer, Jony Hudson, Mike Tarbutt, Ed Hinds The electron is predicted to have a small electric dipole moment (EDM). The size of this fundamental property is intimately connected to the breaking of time reversal symmetry (T) in nature. The Standard Model, which does include a small amount of T asymmetry, predicts the EDM to be too small to ever detect at d$_{\mathrm{e}}$\textless 10$^{\mathrm{38}}$ e.cm. However, many extensions of the Standard Model that suggest additional Tviolation predict the electron's EDM to be within a measurable regime of both current and proposed experiments. This talk describes our YbF electron EDM experiment and introduces some of the technical improvements made to our machine since the last measurement. We have increased the statistical sensitivity of our interferometer by increasing the number of YbF molecules that participate in the experiment and by increasing their detection probability. We demonstrate several hardware developments that combine laser, microwave and rf fields which, when applied to YbF, can pump six times more population into the initial measurement state. In the detection region we have used techniques developed for molecular laser cooling, including resonant polarisation modulation, to dramatically increase the number of scattered photons by a factor of 10. Combining all improvements, the statistical uncertainty of our measurement is expected to be reduced by a factor of ninety, allowing us to search for physics beyond the Standard Model and below the recent upper limit of d$_{\mathrm{e}}$\textless 8.9x10$^{\mathrm{29}}$ e.cm. [Preview Abstract] 
Wednesday, March 16, 2016 11:51AM  12:03PM 
L50.00004: Antiparitytime symmetry via flying atoms Jianming Wen, Liang Jiang, Yanhong Xiao, Peng Peng, Wanxia Cao, Ce Shen, Weizhi Qu We report the first experimental demonstration of optical antiparitytime (antiPT) symmetry [1], a counterpart of conventional PT symmetry [2], in a warm atomicvapor cell. By exploiting rapid coherence transport via flying atoms, our scheme illustrates essential features of antiPT symmetry with an unprecedented precision on phasetransition threshold, and substantially reduces experimental complexity and cost, in contrast to most previous experimental studies relying highly on the advances of nanotechnologies and sophisticated fabrication techniques to synthesize solidstate materials. Of importance, our results represent a significant advance in nonHermitian physics by bridging a firm connection with the field of atomic, molecular and optical physics, where novel phenomena and applications in quantum and nonlinear optics aided by (anti)PT symmetry can be anticipated. [1] P. Peng, W. Cao, C. Shen, W. Qu, J. Wen, L. Jiang, and Y. Xiao, arXiv: 1509.07736 (2015). [2] L. Chang, X. Jiang, S. Hua, C. Yang, J. Wen, L. Jiang, G. Li, G. Wang, and M. Xiao, Nature Photonics \textbf{8}, 524529 (2014). [Preview Abstract] 
Wednesday, March 16, 2016 12:03PM  12:15PM 
L50.00005: Twodimensional atom localization via phasesensitive absorptiongain spectra in fivelevel hyper invertedY atomic systems Zhonghu Zhu, WenXing Yang, AiXi Chen Highprecision measurement of an atomic position through a standingwave field has been the subject of active research over the past few decades because of its potential applications in laser cooling and trapping of neutral atoms, such as atom nanolithography, BoseEinstein condensation, and coherent patterning of matter waves. More recently, twodimensional atom localization, achieved by applying two orthogonal standingwave fields, has been studied extensively for its unique properties. For realizing highprecision twodimensional atom localization, we explore twodimensional atom localization based on phasesensitive probe absorption and gain in a microwavedriven fivelevel hyper invertedY atomic system. Because of the spatial positiondependent atomfield interaction, twodimensional atom localization can be achieved by the measurements of the probe absorption and gain spectra. It was clearly shown that the precision of twodimensional atom localization is extremely sensitive to the detuning of the weak probe field, the intensities of the two control fields, and the relative phase of the driving fields. The main advantage of our proposed scheme is that the maximum probability of finding the atom at an expected position in one period of the standingwave fields is 100{\%}. [Preview Abstract] 
Wednesday, March 16, 2016 12:15PM  12:27PM 
L50.00006: Threebosons in 2D with a magnetic field Seth Rittenhouse, Andrew Wray, Brad Johnson Systems of interacting particles in reduced dimensions in the presence of external fields can exhibit a number of surprising behaviors, for instance the emergence of the fractional quantum Hall effect. Examining fewbody interactions and effects can lead to significant insights within these systems. In this talk we examine a system of three bosons confined to two dimensions in the presence of a perpendicular magnetic field within the framework of the adiabatic hyperspherical method. For the case of zerorange, regularized pseudopotential interactions, we find that the system is nearly separable in hyperspherical coordinates and that, away from a set of narrow avoided crossings, the full energy eigenspectrum as a function of the 2D swave scattering length is well described by ignoring coupling between adiabatic hyperradial potentials. In the case of weak attractive or repulsive interactions, we find the lowest threebody energy states exhibit even/odd parity oscillations as a function of total internal 2D angular momentum and that for weak repulsive interactions, the universal lowest energy interacting state has an internal angular momentum of $M=3$. [Preview Abstract] 
Wednesday, March 16, 2016 12:27PM  12:39PM 
L50.00007: ThreeBody Effects in a ZeroScatteringLength Condensate Lawrence Phillips When pairwise interactions between ultracold Bosons are set to zero using Feshbach resonance, the resulting condensate is well described by replacing the standard twobody contact interaction with a threebody pseudopotential and proceeding with HartreeFock theory in the usual way. We give a prescription for calculating the coupling constant appearing in the threebody pseudopotential, and use it to investigate the dependence of the zeroscatteringlength dynamics upon the original twobody potential. [Preview Abstract] 
Wednesday, March 16, 2016 12:39PM  12:51PM 
L50.00008: Nonadiabatic calculations on hydrogen molecule Jacek Komasa, Krzysztof Pachucki Since its infancy quantum mechanics has treated hydrogen molecule as a test bed. Contemporary spectroscopy is able to supply the dissociation energy ($D_0$) of H$_2$ with the accuracy of $3.7\cdot 10^{4}\ \mathrm{cm}^{1}$, while current theoretical predictions are $10^{3}\ \mathrm{cm}^{1}$ in error. Both the uncertainties are already smaller than the quantum electrodynamic (QED) effects contributing to $D_0$, which poses a particular challenge to theoreticians. Undoubtedly, in order to increase the predictive power of theory one has to not only account for the multitude of the tiny relativistic and QED effects but, especially, significantly increase precision of the largest component of $D_0$the nonrelativistic contribution. We approach the problem of solving the Schroedinger equation, equipped with new methodology, with the target precision of $D_0$ set at the level of $10^{7}\ \mathrm{cm}^{1}$. [Preview Abstract] 
Wednesday, March 16, 2016 12:51PM  1:03PM 
L50.00009: $s$wave resonant shortrange interactions in a $d$dimensional finite volume Shangguo Zhu, Shina Tan It has been known that the energy spectra of few or many particles with shortrange interactions in a finite periodic box are shifted according to the size of the box. In particular, the twobody interaction in a threedimensional box is described by the L\"{u}scher's formulas. Here we study the energy of one particle scattered by a resonant $s$wave shortrange center in a $d$dimensional finite volume. When $d=6$, this onebody problem is mapped to the scattering of three particles in a threedimensional box with a resonant threebody interaction. [Preview Abstract] 
Wednesday, March 16, 2016 1:03PM  1:15PM 
L50.00010: The Bosonic KaneMele Hubbard model Rajbir Nirwan, Ivana Vasic, Alexandru Petrescu, Karyn Le Hur, Walter Hofstetter We investigate the bosonic equivalent of the KaneMele model on the honeycomb lattice [1] including spinorbit and interaction effects. This model is a generalization of the interacting bosonic Haldane model introduced in Ref. [2]. We also allow for an onsite conversion (coherent) term between the two species. We analyze the phase diagram using bosonic dynamical meanfield theory and analytical methods. In the Mott phase, a strongcoupling expansion is performed to investigate the magnetism and frustration effects. A connection is drawn with the quantum theory of an antiferromagnet on a triangular lattice in a magnetic field [3]. This model can be realized in ultracold atom systems with current technology. [1] C. L. Kane and E. Mele, Phys. Rev. Lett. 95, 226801 (2005). [2] I. Vasic, A. Petrescu, K. Le Hur and W. Hofstetter, Phys. Rev. B 91, 094502 (2015). [3] A. V. Chubukov and D. I. Golosov, J. Phys. Cond. Matt. 3 69 (1991). [Preview Abstract] 
Wednesday, March 16, 2016 1:15PM  1:27PM 
L50.00011: Strong correlation effects in a twodimensional Bose gas with quartic dispersion Juraj Radic, Stefan Natu, Victor Galitski We consider a twodimensional Bose gas at zero temperature with an underlying quartic singleparticle dispersion in one spatial direction. This type of band structure can be realized using the NIST scheme of spinorbit coupling, in the regime where the lower band dispersion has the form $\varepsilon_{\textbf{k}} \sim k_{x}^{4}/4+k_{y}^{2}+\ldots$. We numerically compare the ground state energies of the meanfield BoseEinstein condensate (BEC) and various trial wavefunctions, where bosons avoid each other at short distances. We discover that, at low densities, several types of strongly correlated states have an energy per particle ($\epsilon$), which scales with density ($n$) as $\epsilon \sim n^{4/3}$, in contrast to $\epsilon \sim n$ for the weakly interacting Bose gas. These competing states include a Wigner crystal, quasicondensates described in terms of properly symmetrized fermionic states, and variational wavefunctions of Jastrow type, where the latter has the lowest energy and describes a stronglycorrelated condensate. Our results show that even for weaklyinteracting bosons in higher dimensions, one can explore the crossover from a weaklycoupled BEC to a stronglycorrelated condensate by simply tuning the single particle dispersion or density. [Preview Abstract] 
Wednesday, March 16, 2016 1:27PM  1:39PM 
L50.00012: Wave function anatomy of ultracold fermions in a double well: Attractivepairing, Wignermolecules, and entanglement Benedikt B. Brandt, Consatntine Yannouleas, Uzi Landman We report on exact benchmark configurationinteraction computational solutions of the manybody Hamiltonian, uncovering the spectral evolution, wave function anatomy, and entanglement properties of a few interacting ultracold fermions in the entire parameter range, including crossover from an singlewell to a doublewell confinement and a controllable energy imbalance between the wells. According to recent experiments, the two wells are taken as quasionedimensional and both the linear and parrallel configurations of them are considered. We demonstrate attractive pairing and formation of repulsive, highly correlated, ultracold Wigner molecules, associated with the emergence of Heisenberg spin chains.\footnote{Yuesong Li, C. Yannouleas, and U. Landman, Phys. Rev. B {\bf 76}, 245310 (2007); Ying Li, C. Yannouleas, and U. Landman, Phys. Rev. B {\bf 80}, 045326 (2009)} For two fermions, the entanglement measure of the vonNeumann entropy is used as a diagnostic tool for identifying maximally entangled twoqubit Bell states.\footnote{B.B. Brandt, C. Yannouleas, and U. Landman, Nano Lett. {\bf 15}, 7105 (2015).} [Preview Abstract] 
Wednesday, March 16, 2016 1:39PM  1:51PM 
L50.00013: Solvable Models for a Few Atoms in a Few OneDimensional Wells Nathan Harshman This project identifies networks of onedimensional, fewparticle, fewwell models that can be smoothly connected by tuning trap shape and twobody interaction parameters. Solvable models within these networks are identified and analyzed by exploiting symmetries in fewbody configuration space and phase space. In onedimension, ordering permutation symmetry is particularly effective for generating new models. Ordering permutation symmetry is distinct from particle permutation symmetry and arises when there are similar regions in configuration space that are completely disconnected due to unitary interactions and/or infinite well barriers. Realistic experiments with a few atoms or with ultracold gases trapped in effectively onedimensional wells are analyzed by comparison with nearby solvable models using approximation schemes like perturbation theory or variational methods. The transition from systems with a few particles in a few wells to systems with many particles in large lattices can be explored using these techniques. [Preview Abstract] 
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