Bulletin of the American Physical Society
2013 Joint Meeting of the APS Division of Atomic, Molecular & Optical Physics and the CAP Division of Atomic, Molecular & Optical Physics, Canada
Volume 58, Number 6
Monday–Friday, June 3–7, 2013; Quebec City, Canada
Session T4: Opto-Mechanical Systems and Atom Optics |
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Chair: Kevin Mitchell, University of California, Merced Room: 204 |
Friday, June 7, 2013 8:00AM - 8:12AM |
T4.00001: Coupling a small torsional oscillator to large optical angular momentum Hao Shi, Mishkatul Bhattacharya We propose a new optomechanical system to achieve torsional optomechanics. Our system is composed of a windmill-shaped dielectric optically trapped within a cavity interacting with Laguerre-Gaussian cavity modes with both angular and radial nodes. Compared to existing configurations, our proposal enables small mechanical oscillators to interact with the in-principle unlimited orbital angular momentum that can be carried by a single photon, and therefore allows the generation of scalable optomechanical coupling. [Preview Abstract] |
Friday, June 7, 2013 8:12AM - 8:24AM |
T4.00002: ABSTRACT WITHDRAWN |
Friday, June 7, 2013 8:24AM - 8:36AM |
T4.00003: Micro-disk resonator based all-optical switch Dave Clader, Scott Hendrickson, Ryan Camacho, Bryan Jacobs We present theoretical results of a low-loss all-optical switch based on a micro-disk resonator coupled with warm atomic vapor. We examine three and four-level electromagnetically induced transparency control schemes. We show that a control beam can modify the atomic absorption of the evanescent field suppressing the cavity field buildup and altering the path of a weak signal beam. Both schemes should allow for high-contrast all-optical switching of greater than 20 dB with losses below 0.5 dB. Furthermore, our results suggest that in the four-level scheme we can achieve strong optical nonlinearities with control fields corresponding to less than a single photon on average in the cavity. This is due to the strong field confinement of the cavity and quantum coherent effects in the atoms, and does not require strong atom-cavity coupling or cold atoms typically needed to observe nonlinearities with single-photon level intensities. [Preview Abstract] |
Friday, June 7, 2013 8:36AM - 8:48AM |
T4.00004: 1D optical lattice of dark spot traps formed by two nested laser beams for atom transport and quantum information applications Travis Frazer, Katharina Gillen-Christandl One dimensional optical lattices have applications ranging from quantum conveyor belts to quantum computation. Thus far, 1D optical lattices used for this purpose have been limited to trapping atoms in bright spots formed by red-detuned laser light only. Blue-detuned dark spot traps, however, improve coherence times, which allows for more quantum operations before decoherence occurs. There is a lesser known idea that a 1D optical lattice of dark spot traps can be formed using two counter-propagating, blue-detuned laser beams with different beam waists [1]. We will present computational results of our investigation of the properties of these traps both for transporting atoms and performing quantum operations.\\[4pt] [1] P. Zem\'{a}nek, C.J. Foot, Opt. Comm. 146, 119 (1998) [Preview Abstract] |
Friday, June 7, 2013 8:48AM - 9:00AM |
T4.00005: Optically controlled polarizer and waveplate at telecom wavelength for Quantum Zeno Effect based all-optical switch Subramanian Krishnamurthy, Ye Wang, Yanfei Tu, Shih Tseng, Selim Shahriar Quantum Zeno Effect (QZE) is the suppression of the evolution of a quantum state through the quantum measurement process. A manifestation of the QZE occurs when a series of N interlaced waveplates and polarizers prevents the polarization of the input beam from rotating as N approaches infinity. Such a scheme can be used to develop an ultra-low power all-optical switch, by using a tapered nano-fiber embedded in Rb vapor, of the type previously used by us to demonstrate an ultra-low power all-optical modulator. To achieve this goal, it is necessary to realize optically controlled waveplates and polarizers. We have realized both of these effects experimentally, by employing the 5S$_{1/2}$ - 5P$_{1/2}$- 6S$_{1/2}$ ladder transition in $^{87}$Rb, for a probe beam at the telecom wavelength of 1323 nm. Furthermore, we have used a numerical simulation involving all the Zeeman sublevels and velocity averaging to produce results that agree well with experimental results. We have also used this model to identify ways to enhance the contrast for the polarizer and increase the amount of phase retardation for the waveplate while suppressing attenuation. In this talk, we present details of these studies, and discuss the prospect of realizing such a switch using a tapered nano-fiber in Rb vapor. [Preview Abstract] |
Friday, June 7, 2013 9:00AM - 9:12AM |
T4.00006: Coherent Backscattering of Ultracold Atoms Fred Jendrzejewski, Kilian Mueller, Thomas Plisson, Jeremie Richard, Philippe Bouyer, Alain Aspect, Vincent Josse Quantum inference effects play a fundamental role in our understanding of quantum transport through disordered media, as it can lead to the suppression of transport, i.e. Anderson Localization. Convincing as recent observations of Anderson Localization with ultracold atoms are, none of these experiments includes a direct evidence of the role of coherence. For weak disorder, a first order manifestation of quantum interference is the phenomenon of coherent backscattering (CBS), i.e. the enhancement of the scattering probability in the backward direction, due to a quantum interference of amplitudes associated with two opposite multiple scattering paths. In this talk, I present our work on the direct observation of such a CBS peak. A cloud of non-interacting ultra-cold atoms was launched with a narrow velocity distribution in an elongated laser speckle disordered potential. Time of ?ight imaging, after propagation time t in the disorder, directly yield the momentum distribution. The most remarkable feature is the large visibility peak, which builds up in the backward direction. The height and width of that peak, and their evolution with time, are an indisputable signature of CBS, intimately linked to the role of coherence. [Preview Abstract] |
Friday, June 7, 2013 9:12AM - 9:24AM |
T4.00007: Development of an atomic quantum pump: Bose-Einstein condensate scattering from an oscillating barrier Megan Ivory, A.J. Pyle, Tommy Byrd, Kevin Mitchell, John Delos, Kunal Das, Seth Aubin Quantum pumping is a proposed method for generating precise electron transport in mesoscopic systems without applying an external voltage bias. Instead, localized time-varying potentials are used to pump an electron current through a circuit. Quantum pumps offer the prospect of generating highly controlled and reversible currents at the single electron level. Unfortunately, progress towards the experimental realization of such a mechanism in regular conductors has been difficult due to spurious capacitive coupling and rectification effects. As an alternative, we are investigating the use of neutral ultracold atoms instead of electrons to simulate quantum pumping. In addition to avoiding electromagnetic interactions, our ultracold atoms display a high degree of coherence, allowing us to study the quantum aspects of pumping in addition to the classical aspects. As a first step toward implementing a double barrier turnstile pump, we focus on observing and studying scattering of a Bose-Einstein condensate (BEC) from a single oscillating barrier potential. We have recently developed the theory for this type of scattering in classical, semi-classical, and quantum frameworks. We present video simulations of the scattering processes as well as progress towards testing this framework experimentally with a BEC of $^{\mathrm{87}}$Rb. [Preview Abstract] |
Friday, June 7, 2013 9:24AM - 9:36AM |
T4.00008: Optical impulse response of silica microspheres: complementary approach to whispering-gallery-mode analysis Jean-Rapha\"el Carrier, Hugo Bergeron, Julien Roy, Simon Potvin, Vincent Michaud-Belleau, J\'er\^ome Genest, Claudine N\`I Allen Due to their high sensitivity, microspheres are often seen as suitable sensors for applications in biochemistry and quantum electrodynamics. Sensing may be achieved by monitoring the spectral shift of one whispering-gallery mode. However, the information obtainable with this technique is limited since only one mode is tracked. We analyze the optical impulse responses and wide band complex transmission spectra of silica microspheres, as they together provide complementary perspectives to investigate the behaviour of the resonator and its interaction with the surrounding medium. This paper describes how time- and frequency-domain data can be obtained simultaneously with an interferometric setup and how both approaches can be used to better understand the optical dynamics of dielectric microspheres. The impulse response provides confirmation that small asphericities give rise to a precession of the orbit of the pulse propagating around the inner surface of the cavity. This effect also strongly depends on coupling conditions. Moreover, we noticed the presence of secondary pulses associated with modes of higher radial quantum number. All these features bring valuable information on the optical behaviour of the microspheres, which could eventually help increasing sensing possibilities. [Preview Abstract] |
Friday, June 7, 2013 9:36AM - 9:48AM |
T4.00009: Generation of atomic holograms using interferometry, digital holography and BEC Renpeng Fang, Mohamed Fouda, Mehjabin Monjur, May Kim, Jonathan Trossman, John Ketterson, Selim Shahriar We describe a technique where atomic interferometry along with light-shift induced, two dimensional phase imprinting are used to produced 3D holograms of atoms, using a BEC. The condensate is first split into two components, using a Raman pulse. Optical pulses are then used to imprint the desired holographic phase profile (HPP) on one of the split components. To produce the HPP, we first detect, with a focal plane array (FPA), the interference between a plane optical wave and the optical field produced via illumination of a 3D object. The signal is processed for atomic holography, and transferred to a spatial light modulator, which produces the two-dimensional optical pulse that imprints the HPP. The atoms form a 3D hologram upon recombination of the two parts. This technique could be used to produce various topological patterns of condensates for fundamental studies as well for selective population of lattice traps for application to quantum computing. We used the Gross-Pitaevskii equations to model the evolution of the condensate order parameter through free space as well as during interaction with the optical fields. In this talk, we present results of complete simulations of the process for typical three-dimensional patterns, and describe the status of experimental efforts. [Preview Abstract] |
Friday, June 7, 2013 9:48AM - 10:00AM |
T4.00010: Effect of Interatomic Separation and Wavepacket Spreading on the Behavior of a High Compton Frequency Collective State Interferometer Resham Sarkar, May Kim, Yanfei Tu, Selim Shahriar Recently, we proposed an $N$-atom collective state interferometer (CSI), for which the Compton frequency is $N$ times higher than that of a single atom, producing an $N$-fold enhancement of sensitivity. Collective excitation occurs when the inter-atomic distance, $D$, is much less than the transition wavelength. For realizing a CSI, it is important to establish the precise role of $D$ in determining the fidelity of collective excitation. For semi-classical atoms, the excitation is found to consist of a collective state and individual excitations. This yields a condition for the purity of the collective excitation as a function of $D$, taking into account the statistical distribution of $D$. We then take into account the center of mass motion of the atoms, and find that if the atoms are each a plane wave, then the only parameter that governs the extent of collective behavior is $D$. When each atom is assumed to be a wavepacket, we find that this conclusion remains unchanged. Furthermore, we find that the free-spread spreading of the wavepacket does not affect the degree of collective excitation. In this talk, we describe the details of this analysis, and establish conditions necessary for realizing the CSI. [Preview Abstract] |
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