Bulletin of the American Physical Society
47th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 61, Number 8
Monday–Friday, May 23–27, 2016; Providence, Rhode Island
Session U5: Precision Experiments |
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Chair: Ronald Walsworth, Harvard CfA Room: 551AB |
Friday, May 27, 2016 10:30AM - 10:42AM |
U5.00001: Atom interferometric measurement of ``Big G'' on the International Space Station Elizabeth Ashwood, Doga Murat Kurkcuoglu, Charles W. Clark, Mark Edwards 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 rotating--frame Gross--Pitaevskii 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 interferometer sensitivity and the effects of errors. We present two potential schemes as for measuring ``Big G'' on the ISS. These include a Mach--Zehnder--like scheme as well as a design similar to a Foucault Pendulum. [Preview Abstract] |
Friday, May 27, 2016 10:42AM - 10:54AM |
U5.00002: Gravity sensing with Very Long Baseline Atom Interferometry Dennis Schlippert, Henning Albers, Logan L. Richardson, Dipankar Nath, Christian Meiners, Etienne Wodey, Christian Schubert, Wolfgang Ertmer, Ernst M. Rasel Very Long Baseline Atom Interferometry (VLBAI) has applications in high-accuracy absolute gravimetry, gravity-gradiometry, and for tests of fundamental physics. Extending the baseline of atomic gravimeters from tens of centimeters to meters opens the route towards competition with superconducting gravimeters. The VLBAI-test stand will consist of a 10m-baseline atom interferometer allowing for free fall times of seconds. In order to suppress environmental noise, the facility utilizes a state-of-the-art vibration isolation platform and a three-layer magnetic shield. We envisage a resolution of local gravitational acceleration of $5\cdot 10^{-10}$ m/s$^2$ with sub-ppb inaccuracy. Operation as a gradiometer will allow to resolve the gravity gradient at a resolution of $5\cdot 10^{-10}$ 1/s$^2$. The operation of VLBAI as a differential dual-species gravimeter using ultracold mixtures of Yb and Rb atoms enables quantum tests of the universality of free fall (UFF) at an unprecedented level, with the potential to surpass the accuracy of the best experiments to date. We report on a quantum test of the UFF using two different chemical elements, $^{39}$K and $^{87}$Rb, reaching a 100 ppb inaccuracy and show the potential of UFF tests in VLBAI at an inaccuracy of $10^{-13}$ and beyond. [Preview Abstract] |
Friday, May 27, 2016 10:54AM - 11:06AM |
U5.00003: Detecting continuous gravitational waves with a jug of superfluid Swati Singh, Laura De Lorenzo, Aaron B. Pearlman, Igor Pikovski, Keith Schwab We investigate the sensitivity to narrow band, continuous-wave strain fields of a kg-scale optomechanical system formed by the acoustic motion of superfluid helium-4 parametrically coupled to a super-conducting microwave cavity. This narrowband detection scheme is tunable through pressurization of the helium, thereby making both doppler tracking of astrophysical sources and tuning the detector on/off from the source possible. For reasonable experimental parameters, we find that gravitational metric strain fields from nearby pulsars could be detected with a few weeks of integration time. [Preview Abstract] |
Friday, May 27, 2016 11:06AM - 11:18AM |
U5.00004: Calibration of a Larmor clock for tunneling time experiments Jesus Ramos, Shreyas Potnis, David Spierings, Sapehr Ebadi, Aephraim Steinberg How much time does it take for a particle to tunnel? This has been a controversial question since the early times of quantum mechanics. The debate stems mainly from the inability to measure time directly. One proposal to measure the tunnelling time is the Larmor clock, in which the spin degree of freedom of the tunneling particle is used as a clock. This clock only ``ticks" inside the forbidden region due to the precession of the spin about a magnetic field localized within the barrier.~Here, we report the calibration of a Larmor clock to measure tunneling times of a 87 Rb Bose Einstein condensate. We use the Zeeman sublevels of the ground-state F$=$2 manifold and Raman beams for the implementation of a Larmor clock. Experimental progress towards measuring the tunneling time and the challenges involved in this measurement will also be discussed. [Preview Abstract] |
Friday, May 27, 2016 11:18AM - 11:30AM |
U5.00005: Multi-arm spiral electron vortices in multiphoton ionization by circularly polarized pulses Jean Marcel Ngoko Djiokap, Alexei V. Meremianin, Nikolai L. Manakov, Suxing Hu, Lars B. Madsen, Anthony F. Starace Single ionization of helium by single-color two-photon absorption or two-color one-photon/two-photon absorption from two time-delayed circularly-polarized ultraviolet pulses are shown to produce ionized-electron momentum distributions in the polarization plane having respectively \emph{even}-arm (\emph{zero}- and \emph{four}-start) or \emph{odd}-arm (\emph{one}- and \emph{three}-start) spiral vortex structures. Results are obtained by both \emph{ab initio} numerical solution of the six-dimensional two-electron time-dependent Schr\"{o}dinger equation\footnote{J.M. Ngoko Djiokap \emph{et al.}, Phys.~Rev.~Lett. \textbf{115}, 113004 (2015).} and by perturbation theory. The \emph{multi}-arm patterns are sensitive to the carrier frequencies, handedness, time-delay, and relative phase of the two pulses, allowing control of electron angular distributions. \emph{Even}-arm spiral vortices have been observed in optics.\footnote{M. Harris \emph{et al.}, Opt. Commun. \textbf{106}, 161 (1994).} Thus, our \emph{even}-arm spiral electron vortices are a dramatic example of wave-particle duality. Moreover, our \emph{odd}-arm electron matter-wave vortices are consistent with recent findings~\footnote{C. A. Mancuso\emph{et al.}, Phys. Rev. A \textbf{91}, 031402(R) (2015).} in strong-field physics. [Preview Abstract] |
Friday, May 27, 2016 11:30AM - 11:42AM |
U5.00006: Complex Electronic Transport Properties of Warm Dense Lithium Jiayu Dai, Qian Ma, Huayang Sun, Cheng Gao Electronic transport properties such as thermal conductivity and optical absorption of dense plasmas are always a challenging topic in atomic physics, since the environment effect can introduce strong interactions and dynamics contributed by near atoms and temperature. Using quantum molecular dynamics, we studied the ionic structures and optical properties of warm dense Li up to a few hundred GPa and a few eV. The results show that the transport properties are strongly dependent on the electron charge distribution. When the electrons distributed localized, the conductivity becomes lower compared with the free electrons environment. Besides, the optical absorption from atomic model such as detailed level approximation is compared, showing the effect of many body interactions.. [Preview Abstract] |
Friday, May 27, 2016 11:42AM - 11:54AM |
U5.00007: Improving Limits on Exotic Spin Dependent Long Range Forces using Double Boson Exchange Sheakha Aldaihan, William Michael Snow, Dennis Krause, Joshua Long Experimental search for unobserved forces above the submillimeter scale has been an active area of research over the last two decades. The existence of very light weakly interacting particles that mediate such forces has been suggested in many extensions of the Standard Model. The fact that the dark energy density corresponds to a length scale of about 100 $\mu $m also encourages searches for unobserved phenomena at this length scale. Parameterizations of forces in this range show that they can be represented as corrections to the gravitational and electromagnetic forces and have both spin-dependent as well as spin independent components. Very stringent limits on spin-independent couplings exist. For long-range spin dependent forces, limits are weaker by approximately 20 orders of magnitude compared to their spin independent analogs. The disparity in the limits raises the question of whether interesting limits on spin dependent couplings can be inferred from spin independent searches for long range forces. We show that this is possible using higher order contributions corresponding to double boson exchange and derive all possible long range forces arising from double boson exchange. We obtain improved limits on some spin dependent couplings using the leading effects from two boson exchange forces and a recently performed spin independent experiment. [Preview Abstract] |
Friday, May 27, 2016 11:54AM - 12:06PM |
U5.00008: Measurement scheme for a ground-state parity non-conserving (PNC) measurement in a cesium atomic beam via two-pathway coherent control. Jungu Choi, Dan Elliott We present a detailed analysis of an experimental setup for parity non-conserving (PNC) measurements in a cesium atomic beam. We employ a parallel-plate transmission line (PPTL) structure and highly reflective cylindrical mirrors to form a microwave cavity resonator to excite the PNC transitions in the cesium hyperfine ground states. In addition, a variable external dc field is applied to observe the Stark-induced transition, which would interfere with the PNC transition as the dc field amplitude changes. Finally, strong Raman lasers are used to excite the ground hyperfine transition. The Raman fields interfere with the weak transitions, and by varying the phase difference between the Raman fields and the microwave fields, we would infer the weak transition amplitudes from the signal modulation. The experimental setup requires maintaining coherent phase relations between all fields, well-characterized dc and rf field patterns, the two co-propagating Raman lasers, and suppression of the magnetic dipole contribution. Our analysis of the field modes supported by the PPTL structure indicates that with a moderate rf power and a few tens of seconds of data collection time, the PNC measurement of less than 3{\%} uncertainty would be feasible. [Preview Abstract] |
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