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 K5: Quantum Optics and Matter Optics |
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Chair: Pierre Meystre, University of Arizona Room: Knoxville Convention Center 301AB |
Thursday, May 18, 2006 8:00AM - 8:12AM |
K5.00001: Polarization squeezing of ultrashort pulses in fibres Peter Drummond, Joel Corney, Joel Heersink, Vincent Josse, Gerd Leuchs, Ulrik Andersen We report on new experimental data and numerical simulations of quantum polarization squeezing in optical fibres. The experiment is a robust method for producing bright squeezed pulses of light. Because it can produce highly entangled states, the experiment operates in a very nonclassical regime, making the results sensitive to additional dissipative and thermal effects in the fibre. To characterize such experiments, we have performed quantum dynamical simulations of photonic pulses in a birefringent fibre, including all significant quantum effects and thermal noise. We use a novel experimental configuration combined with a detailed theoretical treatment that includes non-Markovian dissipative effects, to allow a quantitative comparison of experiment with quantum dynamical field theory simulations. The theory involves a first principles space-time evolution simulation of a many-body interacting quantum Bose gas, including dissipation. The high quality of the experimental data enables a comparison of simulation and experiment to well below the vacuum noise level, resulting in excellent agreement between theory and experiment over a wide range of pulse energies and fiber lengths. From the simulations, we identify the particular noise sources limiting the squeezing at high and low input energy. [Preview Abstract] |
Thursday, May 18, 2006 8:12AM - 8:24AM |
K5.00002: Optical absorption in a spherical artificial atom Yiming Mi, Shuichi Iwata Considering the nonlocal coupling between the electric field of the incident electromagnetic wave and the polarizability of a spherical semiconductor artificial atom, the optical absorption of the artificial atom is studied theoretically. This nonlocal coupling results in a small size and field dependent shift and broadening of the excitonic resonance. These acquired theoretical results are perhaps of great interest and would get precise experimental validations in future. [Preview Abstract] |
Thursday, May 18, 2006 8:24AM - 8:36AM |
K5.00003: Rotating a Bose-Einstein condensate using photons with orbital angular momentum Mikkel Andersen, Pierre Clade, Changhyun Ryu, Vasant Natarajan, Kristian Helmerson, William Phillips The transfer of spin (or internal) angular momentum from photons to matter has been well understood and studied for a long time. On the other hand, one can use light fields where the photons also carry orbital angular momentum. The first-order Laguerre-Gaussian field is one such light field where each photon carries one unit of orbital angular momentum along its direction of propagation. We experimentally demonstrate that this quantum of angular momentum can be coherently transferred to sodium atoms in a Bose-Einstein condensate (BEC). The experiment uses a set of counter-propagating Gaussian and Laguerre-Gaussian beams, where an atom in the BEC can absorb a photon from one beam and emit a (stimulated) photon into the other beam. We also create vortices with higher angular momentum by transferring the angular momentum of several photons per atom. Finally, we demonstrate the coherent superposition of different rotational states, and show that the phase in these is determined by the phase of the light used for their generation. [Preview Abstract] |
Thursday, May 18, 2006 8:36AM - 8:48AM |
K5.00004: Theory of Raman Superradiance Imaging of Condensed Bose Gases Hermann Uys, Pierre Meystre We investigate superradiant off-resonant Raman scattering of light from an elongated Bose-condensate of atoms. Absorption imaging of superradiant systems yields stronger image contrast than imaging of systems scattering light incoherently. However, the spatial structure of the recoiling atomic fields is not simply proportional to the initial state density. We present a multi-mode theory that reproduces the time evolving spatial features observed in absorption images and accounts for shot-to-shot fluctuations. [Preview Abstract] |
Thursday, May 18, 2006 8:48AM - 9:00AM |
K5.00005: Coherent acceleration of matter waves in circular waveguides Omjyoti Dutta, Markku Jaaskelainen, Pierre Meystre We consider the theory of coherent acceleration of matter waves in a circular waveguide. Loss of coherence during the acceleration process is modeled by taking into account excitations to higher transverse trap levels and the inclusion of classical noise in the accelerating force. The acceleration is optimized in the sense of generating a minimal amount of population in the excited mode in the perturbative limit by using a time dependent acceleration force which has the temporal profile of Blackman pulse. [Preview Abstract] |
Thursday, May 18, 2006 9:00AM - 9:12AM |
K5.00006: Genetic Algorithm approach to Excited Gaussons in Bose-Einstein Condensates with attractive interactions Matt Kalinski Using our recently developed Genetic Algorithm (GC) implementation of the non-fixed node Quantum Difussion Monte Carlo (QDMC) method we find the stationary solutions of the Gross-Pitaevskii equation with the attractive nonlinearity with the Galilean invariance originated from our theory of bright solitons without the inverse scattering transformation. The nodal constraints are randomly tossed for the population of solitons and genetic operations are performed for the lowest energy members of the population for the next generation. Within our theory the ground state bright soliton is approximated by Gausson of the Nonlinear Quantum Mechanics with the Logarithmic nonlinearity and therefore excited solutions, topologically originated from the excited states of the harmonic oscillator are also expected. However those are only possible within the fist nonlinear interation and the second interation alters the potential. Therefore no straightforward analytical theory is possible. The ground state of the nonlinear Schrodinger equation is found with the nonlinear Diffussion Monte Carlo Method. Those are excited solitons in the laboratory frame. Restricted basis Fourier-Mathieu nonlinear theory is also provided as semi-analytical comparison. [Preview Abstract] |
Thursday, May 18, 2006 9:12AM - 9:24AM |
K5.00007: All-optical modeling of superfluid shock waves Jason W. Fleischer, Wenjie Wan The properties of superfluid-like shock waves and interactions are studied by mapping the condensate problem to a beam propagation problem in nonlinear optics. In both cases, a single, macroscopic wavefunction describes the coherent wave behavior of interest, while the shock itself results from a repulsive/defocusing response to a high-density/intensity perturbation. The waves are dissipationless and dispersive, with an oscillating front whose period decreases towards the leading edge. The initial oscillations resemble a train of dark solitons, while the low-intensity regions at the leading edges result in a sound-like profile. Using a nonlinear photorefractive crystal and the power of optical imaging, we directly observe 1D and 2D shock waves, their nonlinear properties as a function of intensity, and double-shock wave collisions. Analytical calculations and numerical simulations show excellent agreement with the experimental results. Further, it is anticipated that the photonic methods established here will lead to all-optical modeling of even richer superfluid phenomena (e.g. turbulence) in the near future. [Preview Abstract] |
Thursday, May 18, 2006 9:24AM - 9:36AM |
K5.00008: Diffraction of 0.5 keV electrons from free-standing transmission gratings Ben McMorran, John Perreault, Tim Savas, Alex Cronin A nanostructured grating was used to diffract a low-energy (500 eV) electron beam, and the current transmitted into the zeroth diffraction order was greater than 5\% of the incident beam current. This diffraction efficiency indicates that the 55-nm-wide grating bars absorb electrons but the 45-nm-wide slots between bars transmit electron de Broglie waves coherently. The diffraction patterns can be asymmetric, and can be explained by a model that incorporates an electrostatic potential energy for electrons within 20 nm of the grating structure calculated by the method of images. [Preview Abstract] |
Thursday, May 18, 2006 9:36AM - 9:48AM |
K5.00009: Interference between competing pathways in the interaction of three-level atoms and radiation Tony Abi-Salloum, Lorenzo Narducci When light interacts with atoms, it can induce transitions by way of distinct but indistinguishable pathways and yield unexpected results. In this talk we discuss the physical origin of the transparency induced in two different Cascade configurations by the simultaneous interplay of the coupling and probe fields. The two studied configurations differ by the different strengths of the applied fields. Probe and coupling fields are switched between configurations. We show, in the inhomogeneous limit, the existence of quantum interference in one configuration which is associated with Electromagnetically Induced Transparency. We also show the absence of interference in the other configuration which is related to the Autler-Townes effect. We use techniques borrowed from quantum scattering theory$^{1}$. The transition amplitude between selected initial and final states offers what we believe is convincing evidence for the appearance, or for the absence, of quantum interference effects. $^{1}$ C. Cohen-Tannoudji, J. Dupont-Roc, and G. Grynberg. Atom-Photon Interactions: Basic Processes and Applications. Wiley (1992). [Preview Abstract] |
Thursday, May 18, 2006 9:48AM - 10:00AM |
K5.00010: Noninvasive imaging in biology using ultrafast coherent control via a pair of chirped pulses Svetlana Malinovskaya, Vladimir Malinovsky The key to advance cutting edge imaging methods in biology is ultrafast pulsed laser techniques that may control vibrational dynamics in molecules. Given vibrational spectra of biological species contain molecular signatures, imaging may be achieved by selective excitation of particular molecular vibrations using stimulated Raman scattering. We present the results of vibrational mode selective excitation using a pair of femtosecond {\em chirped} laser pulses in two-photon Raman scheme, and analyze the possibility of adiabatic population transfer in selected vibrational modes. We also discuss how femtosecond pulse shapes should be modified to take into account decoherence effects present in solution. [Preview Abstract] |
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