Bulletin of the American Physical Society
43rd Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 57, Number 5
Monday–Friday, June 4–8, 2012; Orange County, California
Session T5: Matter-Wave Interferometry I |
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Chair: A. Kumarakrishnan, York University Room: Garden 3 |
Friday, June 8, 2012 8:00AM - 8:12AM |
T5.00001: A Novel Cavity-Based Atom Interferometer Justin Brown, Brian Estey, Holger M\"{u}ller The world's leading atom interferometers are housed in bulky atomic fountains. They employ a variety of techniques to increase the spatial separation between atomic clouds including high order Bragg diffraction. The largest momentum transfer in a single Bragg beamsplitter has been limited to 24 $\hbar k$ by laser power and beam quality. We present an atom interferometer in a 40 cm optical cavity to enhance the available laser power, minimize wavefront distortions, and control other systematic effects symptomatic to atomic fountains. We expect to achieve spatial separations between atomic trajectories comparable to larger scale fountains within a more compact device. We report on our progress in developing this new interferometer using cold Cs atoms and discuss its prospects for exploring large momentum transfer up to 100 $\hbar k$ in a single Bragg diffraction process. The compact design will enable the first demonstration of the gravitostatic Aharonov-Bohm effect. [Preview Abstract] |
Friday, June 8, 2012 8:12AM - 8:24AM |
T5.00002: High data-rate atom interferometer for measuring acceleration Akash Rakholia, Hayden McGuinness, Grant Biedermann Atom interferometers have the potential to be exceptional broadband inertial sensors in both translational and rotational degrees of freedom. The demonstrated performance of this technology rivals the best ring-laser gyroscopes and falling corner-cube gravimeters. However, compact and field-worthy manifestations of atom interferometers remain elusive using standard approaches. Furthermore, bandwidths have typically been limited to a few Hertz, which is insufficient for a broader application space. We demonstrate a high data-rate light-pulse atom interferometer for measuring acceleration. The device is optimized to operate at rates between 50 Hz to 330 Hz with sensitivities of 0.57 micro-g/rtHz to 36.7 micro-g/rtHz, respectively. Our method offers a dramatic increase in data rate and demonstrates a path to new applications in highly dynamic environments. [Preview Abstract] |
Friday, June 8, 2012 8:24AM - 8:36AM |
T5.00003: Measurements of gravitational acceleration from an echo atom interferometer C. Mok, A. Carew, B. Barrett, R. Berthiaume, A. Kumarakrishnan We have developed two techniques involving a ground-state, time-domain echo atom interferometer (AI) to measure gravitational acceleration, $g$, from a sample of laser-cooled atoms. We compare and contrast measurements from a two-pulse and a three-pulse stimulated-echo AI described in PRA \textbf{84}, 063623 (2011). The two-pulse AI involves excitation by standing wave pulses separated in time by $T_{21}$, and detection at $2T_{21}$. In this case, the accumulation of the matter-wave fringes as a function of $T_{21}$ is described by a frequency chirped signal analogous to the interference fringes recorded by a falling corner-cube Mach-Zehnder optical interferometer. In contrast, the three-pulse stimulated echo AI requires excitation by standing wave pulses separated by $T_{21}, T_{32}$ and detection at $2T_{21}+T_{32}$. In this case, the signal from the AI as a function of $T_{32}$ is modulated at a single frequency determined by $T_{21}$. Since the three-pulse AI is less sensitive to mirror vibrations and magnetic gradients, the measurement timescale is appreciably increased. We also consider the implementation of a RF-optical feedback loop to actively stabilize both AIs from the effects of mirror vibrations. [Preview Abstract] |
Friday, June 8, 2012 8:36AM - 8:48AM |
T5.00004: Progress towards a test of the universality of free fall using a $^{6}$Li-$^{7}$Li atom interferometer Paul Hamilton, Tom Barter, Geena Kim, Biswaroop Mukherjee, Holger M\"{u}ller Measurements of the acceleration of gravity for bodies of differing compositions have long been used to test the universality of free fall (UFF), one part of the equivalence principle underlying general relativity. A ${^6}$Li-${^7}$Li matter wave interferometer test of UFF would have high sensitivity to new physics because of the relatively large difference between $^{6,7}$Li nuclei~[1]. An optical lattice will be loaded with $^{6}$Li and $^{7}$Li atoms from a dual species 2D/3D-magneto-optical trap. The lattice will then be employed both as a waveguide to prevent atom losses due to the high thermal velocity of Li, and as large momentum transfer beam splitters in analogy to the Bloch-Bragg-Bloch beam splitters already developed by us~[2,3]. We anticipate an accuracy of $10^{-14}g$ for the differential acceleration measurement. We discuss investigations of novel all-optical cooling of lithium using degenerate Raman sideband cooling as well as recent progress towards a demonstration of the first ultracold lithium interferometer. \\[4pt] [1] M. Hohensee et al., J. Mod. Optics {\bf 58}, 2021 (2011) \\[0pt] [2] H. M\"{u}ller et al., Phys. Rev. Lett. {\bf 100}, 180405 (2008) \\[0pt] [3] H. M\"{u}ller et al., Phys. Rev. Lett. {\bf 102}, 240403 (2009) [Preview Abstract] |
Friday, June 8, 2012 8:48AM - 9:00AM |
T5.00005: Towards Testing General Relativity with a dual species interferometer Dennis Schlippert, Jonas Hartwig, Daniel Tiarks, Ulrich Velte, Sven Ganske, Wolfgang Ertmer, Ernst M. Rasel We report on our work directed towards a dual species matter-wave interferometer for performing a differential measurement of the acceleration of free falling $^{87}$Rb and $^{39}$K atoms to test Einstein's equivalence principle (universality of free fall). Based on minimal Standard Model Extension calculations this combination of test masses is more sensitive to composition based equivalence principle violating effects than, e.g. $^{85}$Rb-$^{87}$Rb. During free fall, a Mach-Zehnder type interferometry sequence employing stimulated Raman transitions is applied synchronously for both species, achieving high common noise rejection. With an expected single shot resolution of $~ 5\times 10^{-8}g$ the apparatus will allow for studying systematics at the $10^{-9}g$ level after 100 s integration time. Post-correction methods for high vibrational noise environments are investigated. To assure well defined starting conditions the two species will be trapped in an optical dipole trap. The properties of this trap at $2$ $\mu$m allow for fast and efficient laser cooling, use of evaporative and sympathetic cooling techniques is possible. We will show the enviromental noise limited performance of the single species Rb gravimeter and the progress of the implementation of the K gravimeter. [Preview Abstract] |
Friday, June 8, 2012 9:00AM - 9:12AM |
T5.00006: Large momentum transfer atom interferometry with Coriolis force compensation Pei-Chen Kuan, Shau-Yu Lan, Brian Estey, Philipp Haslinger, Holger Mueller Light-pulse atom interferometers use atom-photon interactions to coherently split, guide, and recombine freely falling matter-waves. Because of Earth's rotation, however, the matter-waves do not recombine precisely, which causes severe loss of contrast in large space-time atom interferometers. I will present our recent progress in using a tip-tilt mirror to remove the influence of the Coriolis force from Earth's rotation. Therefore, we improve the contrast and suppress systematic effects, also reach what is to our knowledge the largest spacetime area. [Preview Abstract] |
Friday, June 8, 2012 9:12AM - 9:24AM |
T5.00007: A Schroedinger Cat Matter Wave Gyroscope Using Collective Excitation of Atomic Ensembles Selim Shahriar, Resham Sarkar, May Kim, Yanfei Tu The phase shift in an atom interferometric gyroscope (AIG) of area A, induced by a rotation rate of $\Omega $, is given by $\delta \varphi =2A\Omega m/\hbar $, where $m$ is the mass of the atom. This is seen transparently when we consider the time delay (computed using special relativistic dynamics) between the signals arriving at a detector, given by $\delta t=2A\Omega /C^2$. The phase shift is found by multiplying the delay by the Compton frequency, $mC^2/\hbar$. The fact that the Compton frequency of an alkali atom is nearly ten orders of magnitude larger than a typical optical frequency is the basic reason why an AIG is much more sensitive than an optical gyroscope. In this talk, we describe a matter-wave gyroscope with a Compton frequency much larger than that of a single atom. Here, an ensemble of atoms are excited by two counter-propagating Raman beams corresponding to a $\Lambda $ transition. In the limit of symmetrized collective excitation, the ensemble can then be split, with a recoil of $2\hbar k/(Nm)$, where N is the number of atoms in the ensemble. Using the standard $\pi $/2-$\pi -\pi $/2 excitation sequence results in a gyroscope with $\delta \varphi =2A\Omega Nm/\hbar $, since the Compton frequency is larger by a factor of N. [Preview Abstract] |
Friday, June 8, 2012 9:24AM - 9:36AM |
T5.00008: Superfluid rotation sensor with helical laser trap Alexey Okulov The macroscopic quantum states of cold atomic ensemble\footnote{F. Dalfovo et al. Rev.Mod.Phys., \textbf{71}, 463 (1999).} in helical laser trap\footnote{A.Yu.Okulov. J. Phys. B , \textbf{41}, 101001 (2008).} are considered in the framework of the Gross-Pitaevskii equation. The helical interference pattern is composed of the two counter propagating Laguerre-Gaussian optical vortices with opposite orbital angular momenta and they are driven in rotation via angular Doppler effect.\footnote{A.Yu.Okulov. J. Opt. Soc. Am. B, \textbf{29}, in press (2012).} The macroscopic observables including linear momentum and angular momentum are evaluated explicitly.\footnote{A.Yu.Okulov. Phys.Lett.A, \textbf{376}, 650-655 (2012).} [Preview Abstract] |
Friday, June 8, 2012 9:36AM - 9:48AM |
T5.00009: Rotation measurement using a grating-echo interferometer Adam Carew, Brynle Barrett, A. Kumarakrishnan We discuss a proof-of-principle measurement of rotation using a grating echo atom interferometer. Cold atoms are launched horizontally across the excitation beams and rotation is measured as a phase shift in the echo signal due to the Sagnac effect. Radiofrequencies for the excitation beams are derived from phase-locked loops, referenced to a Rb clock. These excitation beams are pulsed, counter-propagating, blue-detuned travelling waves, having a small frequency difference ($\delta$) with respect to each other. The experiment requires the application of two such pulses, separated by t=T, with the second pulse having opposite k-vectors to the first. The atomic density grating formed in the vicinity of t=2T is detected by applying a travelling-wave read-out pulse, in the presence of a counter-propagating interrogation pulse, which is detuned from the readout by 10 MHz. The effect of rotation manifests as a phase shift in the beat note between the interrrogation beam and the back-scattered signal. The magnitude of the Sagnac shift is varied by changing the launch velocity of the atomic cloud. Averaging the signal as a function of $\delta$ over T generates a ground-state Ramsey fringe pattern with a shifted central fringe. [Preview Abstract] |
Friday, June 8, 2012 9:48AM - 10:00AM |
T5.00010: Sagnac Interferometry with Bose-Einstein Condensates in a Uniformly Rotating Ring Trap Marty Kandes, Michael Bromley We present the results of numerical simulations studying a novel scheme to perform Sagnac interferometry with Bose-Einstein condensates in a uniformly rotating ring trap. The proposed scheme involves determining the relative phase shifts between two counter-propagating condensate wavepackets as the angular velocity of the ring trap is varied. Analyzing the interference patterns obtained from the simulations, we find that, for the most part, the phase shift response closely follows that predicted by the Sagnac effect, even when the nonlinear mean-field interaction of the condensate is large. However, we unexpectedly find that the linear accumulation of the relative phase shift with respect to time manifests itself as step-like phase jumps during collisions of the wavepackets, with the magnitude of the phase jumps being linearly dependent upon the angular velocity of the rotating ring trap and the angular momenta of the wavepackets. We provide details of the proposed scheme and discuss some of the advantages this unexpected behavior in the phase shift response may offer in performing Sagnac interferometry with Bose-Einstein condensates in the future. [Preview Abstract] |
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