Bulletin of the American Physical Society
2006 37th Meeting of the Division of Atomic, Molecular and Optical Physics
Tuesday–Saturday, May 16–20, 2006; Knoxville, TN
Session C6: Atom Optics and Atom Interferometry |
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Chair: Jennifer Sebby-Strabley, National Institute of Standards and Technology Room: Knoxville Convention Center 301C |
Wednesday, May 17, 2006 10:30AM - 10:42AM |
C6.00001: Direct imaging of periodic sub-wavelength patterns generated by optical phase masks Alexei Tonyushkin, Tycho Sleator We demonstrated {\em direct} imaging of interference fringes of total atomic density with period $\lambda /4$ and $\lambda /2$ for optical wavelength $\lambda$ that have been produced in de Broglie wave atom interferometer. The imaging was done by means of an ``optical mask" technique\footnote{A.~Turlapov, A.~Tonyushkin, and T.~Sleator, PRA {\bf 68}, 023408 (2003).}, which allowed us to observe sub-wavelength periodic patterns with a resolution of up to $\lambda /16$. In addition, the dependence of the fringe pattern on the recoil phase and pulse areas reveals quantum dynamics in the atomic center-of-mass motion. The behavior of the fringe patterns near the interference times distinguishes the effects of phase gratings from those of amplitude gratings.\footnote{A.~Tonyushkin, and T.~Sleator, arXiv:physics/0512016 (2005).} [Preview Abstract] |
Wednesday, May 17, 2006 10:42AM - 10:54AM |
C6.00002: Demonstration of Long coherence Times in Guided Atom Interferometers Saijun Wu, Edward Su, Tao Hong, Mara Prentiss For the first time, we demonstrate that guiding atoms increases the interrogation time in an interferometer by preventing the atom sample from expanding and falling under gravity as it would if the same atom sample were left in free space. ~The increase in interrogation time is approximately a factor of 2, with guided atom interrogation times exceeding 25 ms. Our atom interferometers are based on Talbot-Lau interferometry. We will discuss decay mechanisms for the interference fringe contrast and point out new directions in atom optics and precision measurment opened by our guiding techniques. [Preview Abstract] |
Wednesday, May 17, 2006 10:54AM - 11:06AM |
C6.00003: High-Order Quantum Resonances Observed in a Periodically-Kicked Bose Condensate Changhyun Ryu, Mikkel Andersen, Alipasha Vaziri, Michael d'Arcy, Joshua Grossman, Kristian Helmerson, William Phillips We have observed high-order quantum resonances in a realization of the quantum $\delta $-kicked rotor, using Bose-condensed Na atoms subjected to a pulsed standing wave of laser light. These resonances occur for pulse intervals that are rational fractions of the Talbot time, and are characterized by ballistic momentum transfer to the atoms. The condensate's narrow momentum distribution not only permits the observation of the quantum resonances at 3/4 and 1/3 of the Talbot time, but also allows us to study scaling laws for the resonance width in quasimomentum and pulse interval. [Preview Abstract] |
Wednesday, May 17, 2006 11:06AM - 11:18AM |
C6.00004: Measurement of atomic diffraction phases induced by material gratings John Perreault, Alexander Cronin Atom-surface interactions can significantly modify the intensity and phase of atom de Broglie waves diffracted by a silicon nitride grating. This affects the operation of a material grating as a coherent beam splitter. The phase shifts induced by diffraction are measured by comparing the relative phases of serveral interfering paths in a Mach-Zehnder Na atom interferometer formed by three material gratings. The values of the diffraction phases are consistent with a simple model which includes a van der Waals atom-surface interaction between the Na atoms and the silicon nitride grating bars. [Preview Abstract] |
Wednesday, May 17, 2006 11:18AM - 11:30AM |
C6.00005: Coherence properties of an ultracold atom beam in a circular waveguide Kevin Moore, Subhadeep Gupta, Kater Murch, Dan Stamper-Kurn We present a theoretical exploration and an experimental implementation of superradiant pump-probe spectroscopy to study the coherence properties of quantum degenerate atoms propagating in a circular waveguide. Superradiant Rayleigh scattering in the context of a coherent, rotating, and expanding atom pulse exhibits strong geometric dependencies which connect to tomographic measurements of the Wigner function and can aid the characterization of pulsed atom beams propagating in waveguides. The atomic beam propagating in our circular wave guide exhibits mean-field limited single-mode propagation, maintains long-range coherence after multiple orbits, and can be coherently split into momentum states which simultaneously orbit the storage ring in opposite directions. [Preview Abstract] |
Wednesday, May 17, 2006 11:30AM - 11:42AM |
C6.00006: Interference of Bose-Einstein Condensates on an Atom Chip G.-B. Jo, Y. Shin, C. Sanner, T.A. Pasquini, M. Saba, S. Will, W. Ketterle, D.E. Pritchard, M. Vengalattore, M. Prentiss We have used a microfabricated atom chip to split a single Bose-Einstein condensate of sodium atoms into two spatially separated condensates [1]. Dynamical splitting was achieved by deforming the trap along the tightly confining direction into a purely magnetic double-well potential. We observed the matter wave interference pattern formed upon releasing the condensates from the microtraps. The intrinsic feature of the quartic potential at the merge point, such as zero trap frequency and extremely high field-sensitivity, caused random variations of the relative phase between the two split condensates. Recent experimental progress will be discussed. [1] Y. Shin, et.al., Phys. Rev. A \textbf{72}, 021604 (2005) [Preview Abstract] |
Wednesday, May 17, 2006 11:42AM - 11:54AM |
C6.00007: Atom Quantum Interference Device. Michele Saba, Gyuboong Jo, Tom Pasquini, Yong-Il Shin, Caleb Christiansen, Sebastian Will, Wolfgang Ketterle, David Pritchard We experimentally realize a weak link between two Bose-Einstein condensates with a stream of atoms moving with two photon recoils [1]. The flux of atoms is proven to depend on the relative phase between the two condensates in the same way that the flux of Cooper pair in a Josephson junction depends on the phase between two superconducting islands. Differently from a Josephson junction though, the phase accumulated by the atoms while traveling from one condensate to the other can be controlled experimentally by fine tuning their recoil velocity. This peculiarity of the atomic system stems from the large size and accessibility of atomic junctions with respect to solid state ones. We will elaborate on the scientific offspring of the experiment, like the prospect of realizing highly non-classical distribution of atoms between two condensates, and on the technical one, like the possibility of turning the atomic junction into a ring gyroscope that detects the Sagnac phase induced by rotations. [1] Y. Shin, G.-B. Jo, M. Saba, T. A. Pasquini, W. Ketterle, and D. E. Pritchard, Optical Weak Link between Two Spatially Separate Bose-Einstein Condensates Phys. Rev. Letters 95, 170402 (2005) [Preview Abstract] |
Wednesday, May 17, 2006 11:54AM - 12:06PM |
C6.00008: BEC transistor James Stickney, Dana Anderson, Alex Zozulya In the past decade, considerable efforts have been spent developing BEC based devices for applications such as fundamental research, precision measurements, and quantum information technology. These devices, capable of complex functionality, may be constructed from simple building blocks. New atom-optical components will enable researchers to build more elaborate integrated devices. One of the most important components of microelectronics is the transistor. We are proposing a device that shows behavior reminiscent of a transistor, which enables one to control a large number of atoms with a smaller number. This device utilizes three atom traps where the atoms in the left act as the source in a field effect transistor, the atoms in the middle act as the gate, and the right trap is the drain. When the middle trap is empty, atoms cannot tunnel from the left through the middle and in to the right, because the chemical potential in the middle trap is sufficiently smaller than that in the left or right to block tunneling. If a small number of atoms are placed in the middle, the device switches enabling tunneling from the left to the right. This tunneling is due to the fact that atom-atom interactions increase the chemical potential in the middle trap and remove the energy mismatch. We show that the number of atoms tunneling into the right can be much larger than the number of controlling atoms in the middle. Thus, the three trap structure demonstrates both absolute and differential gain, and that it can be used as an atomic transistor. [Preview Abstract] |
Wednesday, May 17, 2006 12:06PM - 12:18PM |
C6.00009: A new Michelson interferometer for Bose-Einstein condensates G. Ofir Garcia, Kenneth Baranowski, Benjamin Deissler, K. Jeramy Hughes, Jessica Reeves, Cass Sackett We have implemented a Michelson interferometer for Bose-Einstein condensates using $^{87}$Rb atoms confined in a novel magnetic waveguide structure. Features of the guide include a rotating bias field that suppresses noise from external magnetic fields and weak confinement strength that reduces the decohering effects of atomic interactions. The atoms are manipulated using Bragg scattering from an off-resonant standing light wave, with which we have demonstrated a new and efficient way to reverse the atomic motion. For short propagation times, we observe nearly perfect interferometer contrast. The sensitivity of an atom interferometer typically scales quadratically with the interaction time that can be achieved. We have so far achieved an interaction time of 24 ms while maintaining 70\% fringe visibility. To our knowledge, this is more that twice as long as the best previous observations. We shall discuss progress and barriers towards extending the time further. [Preview Abstract] |
Wednesday, May 17, 2006 12:18PM - 12:30PM |
C6.00010: Quantum theory of atom lasers Tobias Kramer, Mirta Rodriguez Pinilla, Christian Bracher Quantum theory of atom lasers We present a fully quantum mechanical and largely analytical theory for the properties of coherent atomic beams in the gravitational field. The results describe both the total emission rate and the beam profile. Depending on the size of the atomic cloud and the strength of interactions, the theory predicts a transverse substructure in the atomic beam. A simple picture in terms of a virtual point source allows us to describe interaction effects analogous to the effect of an optical lens. Recent experiments on atom laser beam profiles are in good agreement with the model. For more information, see also http://people.deas.harvard.edu/$\sim$tkramer [Preview Abstract] |
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