Bulletin of the American Physical Society
42nd Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 56, Number 5
Monday–Friday, June 13–17, 2011; Atlanta, Georgia
Session U5: Non Linear Optics |
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Chair: Daniel Gauthier, Duke University Room: A705 |
Friday, June 17, 2011 10:30AM - 10:42AM |
U5.00001: Optical Information and Light-Matter Interactions in a Bose-Einstein condensate L. Suzanne Leslie, Azure Hansen, Justin T. Schultz, Nicholas P. Bigelow Information can be coherently transferred between light and matter. Our approach uses a two-photon Raman interaction in a lambda configuration to encode the difference in the electric fields into the spinor wavefunction of a Bose-Einstein condensate (BEC). This process simultaneously transfers population between the initial and final states of the lambda system, and creates a coherence between the populated states. By choosing a defocused Gaussian and a tightly-focused Laguerre-Gaussian (LG) beam for the Raman beam pair, the doughnut intensity profile and the azimuthal phase winding of the LG beam can be written into the condensate and stored as a spin texture called a coreless vortex. We use density matrices to model this interaction in all three spatial dimensions as well as time. [Preview Abstract] |
Friday, June 17, 2011 10:42AM - 10:54AM |
U5.00002: Atomic State Localization using EIT in Cold Atoms Zach Simmons, Nicholas Proite, Deniz Yavuz We present a proof-of-principle experiment in which the population of an atomic level is spatially localized using EIT. We exploit the nonlinear dependence of atomic level transfer on the ratio of probe and coupling powers in EIT. By employing a spatially varying coupling beam, it is possible to localize an atomic state to only where the coupling beam nearly vanishes. In a Rb MOT experiment, we demonstrate this by showing that the population of a specific hyperfine level is localized to a region much smaller than the spatial period of the applied sinusoidally varying coupling beam. This technique shows promise for manipulating atoms at sub-wavelength and possibly nanometer spatial scales, with potential important applications in quantum computing and high resolution imaging. [Preview Abstract] |
Friday, June 17, 2011 10:54AM - 11:06AM |
U5.00003: Electromagnetically-induced transparency using cylindrical vector beams Fredrik Fatemi, Guy Beadie Cylindrical vector beams (CVBs), which have an azimuthally varying polarization profile, are ideal for investigating polarization-dependent effects in a single measurement. In this work, we demonstrate EIT with a uniform pump field that is probed by the CVB in a warm vapor of Rb85. The CVB can be formed containing either all linear polarizations or all degrees of ellipticity. The presence of EIT is recorded by a CCD camera so that the effects of different polarizations can be distinguished simultaneously. The polarization dependence of EIT results in strong spatial modulation of the transmitted probe intensity. We discuss our technique for generating the CVBs, interpret the images based on the relevant coupling strengths, and discuss future CVB experiments and applications. [Preview Abstract] |
Friday, June 17, 2011 11:06AM - 11:18AM |
U5.00004: Spatially Resolved Object Detection Using Entangled Twin Beams Jeremy Clark, Zhifan Zhou, Quentin Glorieux, Ulrich Vogl, Paul Lett It has been demonstrated that squeezed twin beams of light generated using four-wave mixing in hot rubidium vapor can produce multiple simultaneously entangled spatial modes allowing for the production of ``entangled images.'' We propose, model, and experimentally investigate schemes that would exploit these quantum correlations in order to resolve the shape of a mask partially obstructing one of the twin beams. In one scheme we generate twin beams of squeezed vacuum using four-wave mixing on the D1 line of 85Rb and place an arbitrarily shaped mask in the path of one of the quantum correlated squeezed vacuum fields. We simultaneously perform balanced homodyne detection on both the obstructed beam as well as its unobstructed twin with matched local oscillators that are dynamically shaped using a spatial light modulator. The spatial light modulator can then be programmed to search for the local oscillator shape that matches that of the squeezed vacuum leaking through the mask. By using information obtained by the detection of both beams we can resolve the shape of the partially obstructing mask with an enhanced sensitivity unobtainable using classical states of light. [Preview Abstract] |
Friday, June 17, 2011 11:18AM - 11:30AM |
U5.00005: Degenerate four-wave mixing in atomic ytterbium Tian Li, Ryan Baker, Jonathan Weinstein We have performed degenerate four-wave mixing experiments with cryogenically-cooled atomic ytterbium. We use buffer-gas cooling to prepare high optical density samples at a temperature of 4.2 K, cold enough to resolve the different isotopes and hyperfine transitions. We observe four-wave mixing and the creation of a conjugate beam when the laser is closely detuned from the $^1S_0 (F=1/2) \rightarrow ^1P_1 (F=1/2)$ transition of the $^{171}$Yb ($I=1/2$) isotope. Progress towards the generation of nonclassical light will be discussed. [Preview Abstract] |
Friday, June 17, 2011 11:30AM - 11:42AM |
U5.00006: Studies of Raman Transitions in Cold Atoms in Arbitrary Magnetic Fields Frank Narducci, Jon Davis, Emily Clifton, Sara DeSavage, Kyle Gordon Raman transitions are ubiquitous in atomic and molecular systems. Of particular interest to us is the application of Raman transitions as atom beam splitters and as atom mirrors: specifically of the type that might be used in the construction of a gradient magnetometer atom interferometer. In contrast to other types of interferometers, e.g. gravimeters, gravity gradiometers and gyroscopes, a magnetic gradiometer interferometer requires the use of magnetically sensitive Zeeman levels in the Raman process. We report our theoretical studies of the Raman resonances in arbitrary magnetic fields for various polarizations of the Raman driving fields. We present experimental measurements performed in a cold sample of 85Rb with both orthogonal linear and parallel circular polarization for the Raman fields. A novel and time efficient detection scheme is presented. [Preview Abstract] |
Friday, June 17, 2011 11:42AM - 11:54AM |
U5.00007: Pattern Formations for Optical Switching Using Cold Atoms as a Nonlinear Medium Bonnie Schmittberger, Joel Greenberg, Daniel Gauthier The study of spatio-temporal pattern formation in nonlinear optical systems has both led to an increased understanding of nonlinear dynamics as well as given rise to sensitive new methods for all-optical switching. Whereas the majority of past experiments utilized warm atomic vapors as nonlinear media, we report the first observation of an optical instability leading to pattern formation in a cloud of cold Rubidium atoms. When we shine a pair of counterpropagating pump laser beams along the pencil-shaped cloud's long axis, new beams of light are generated along cones centered on the trap. This generated light produces petal-like patterns in the plane orthogonal to the pump beams that can be used for optical switching. [Preview Abstract] |
Friday, June 17, 2011 11:54AM - 12:06PM |
U5.00008: Bright Photon Pair Source with High Spectral and Spatial Purity J. Schaake, R. Bennink, P. Evans, W. Grice, T. Humble We report the design and experimental characterization of a down-conversion source that has been optimized for high spectral and spatial purity. Spectral purity is achieved through the choices of the pump properties and phase-matching characteristics. Spatial entanglement is minimized via a collinear configuration in non-critically phase-matched periodically poled potassium titanyl phosphate. This geometry eliminates walk-off effects and maximizes the overlap of the pump, signal, and idler fields. With a properly focused pump, nearly all of the photons are emitted into a single spatial mode, thus yielding a single-mode emission rate of 123,000 pairs/s/mW. With its high brightness and spectral and spatial purity, this source is ideal for experiments requiring multiple pairs of identical photons, or for use as a heralded single-photon source. In addition to describing the methods for eliminating the spectral and spatial entanglement, we also show how the source can be configured to produce \emph{N}-photon polarization-entangled states. [Preview Abstract] |
Friday, June 17, 2011 12:06PM - 12:18PM |
U5.00009: Generation of Squeezed Light via Phase-Sensitive Amplification Neil Corzo-Trejo, Alberto Marino, Quentin Glorieux, Kevin Jones, Paul Lett A phase-sensitive amplifier (PSA) is based on a parametric process that can amplify or deamplify a signal depending on the phase of the input. It does so without degrading the signal-to-noise ratio of the input, making it possible to obtain noiseless amplification of signals. Furthermore the PSA can generate bright quadrature squeezed states of light and, when working unseeded, vacuum squeezed light. We present experimental results on the generation of quadrature squeezed light via phase-sensitive optical amplification based on four-wave mixing in hot $^{85}$Rb vapor. The squeezing is observed for a wide range of pump powers and probe detunings on the D1 line. The squeezing is present in different transverse modes of the single output beam, making our system one of the first sources of multi-spatial-mode quadrature squeezed light. The maximum squeezing observed is -2.8 $\pm $ 0.2 dB, which is consistent with the best results reported using atomic vapors. We have also observed that this system can amplify signals without a significant degradation of the signal-to-noise ratio. [Preview Abstract] |
Friday, June 17, 2011 12:18PM - 12:30PM |
U5.00010: Dual All-optical OR/NOR Logic Gates in Hot Rubidium Vapor Zhifan Zhou, Jietai Jing, Cunjin Liu, Jun Zhou, Weiping Zhang We experimentally demonstrate a dual all-optical or/nor gate with rapid gate time and low power consumption. Based on four wave mixing(FWM) in a double-lambda system in a rubidium vapor, we observed twobright spots in the output conical emission after proper phase-matching adjustments. We feed the two output spots back into the vapor as the controlled seeding. Thanks to FWM enhanced by atomic coherence, the two feedback seeding beams can independently induce switching of outputs to orthogonal directions, fulfilling an all-optical ``NOR'' logic gates for initial state and ``OR'' gate for the switched state simultaneously. The process is featured with rapid response while we show the weak beams are capable of controlling strong beams. The residual power in the conical emission is only 8{\%} of the induced power during the gate operations. The present demonstration has potential applications in the field of all-optical logic devices [Preview Abstract] |
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