Bulletin of the American Physical Society
2005 36th Meeting of the Division of Atomic, Molecular and Optical Physics
Tuesday–Saturday, May 17–21, 2005; Lincoln, Nebraska
Session F4: Quantum Optics, Matter Optics, and Coherent Control |
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Chair: Mark Raizen, University of Texas at Austin Room: Burnham Yates Conference Center Hawthorne |
Thursday, May 19, 2005 10:30AM - 10:42AM |
F4.00001: High-efficiency phase-shaped ultra-broadband non-collinear optical parametric amplifier (NOPA) Andrei Florean, Elizabeth Carroll, Brett Pearson, Roseanne Sension, Philip Bucksbaum We present an improved NOPA scheme, which allows us to generate ultra-broadband pulses, extending from 490nm to 830nm. The beam's spatial profile is Gaussian, with 5$\mu $J typical energy, while the input blue energy is 15$\mu $J/45$\mu $J respectively for the 2 passes (8{\%} efficiency). The design is based on two stages amplification in 2mm thick BBO crystals, and it uses a Pellin-Broca prism placed in the pump's path. The purpose of the prism is to stretch the pump in time and to increase its chromatic angular divergence, both effects enhancing the amplified bandwidth. In addition we present a software model, which predicts the best non-collinear NOPA angle for a set pump central wavelength and desired amplified bandwidth. We phase-shape the NOPA output in a 4f prism-based shaping system, by means of a 128 pixels liquid crystal modulator (LCM), with less than 35{\%} losses. Because of the limited LCM size we decrease the NOPA bandwidth. The compression is coarsely attained with a BK7 prism compressor and then finely tuned with the LCM, by using a SHG signal in a 40 $\mu $m BBO crystal as feedback in a genetic algorithm (GA) run. The output is used in molecular feedback-controlled experiments. [Preview Abstract] |
Thursday, May 19, 2005 10:42AM - 10:54AM |
F4.00002: Einstein-Podolsky-Rosen correlations using dissociation of a molecular Bose-Einstein condensate Karen Kheruntsyan, Murray Olsen, Peter Drummond We combine two of Einstein's contributions to twentieth century physics, Bose-Einstein condensation and the Einstein-Podolsky-Rosen (EPR) paradox, to propose a test of local realism with mesoscopic numbers of massive particles. Using dissociation of a Bose-Eistein condensate of homonuclear diatomic molecules into the constituent bosonic atoms, we demonstrate that strongly entangled output atomic beams may be produced which possess nonlocal EPR correlations in particular field quadratures [1]. These are directly analogous to the position and momentum correlations originally considered by EPR, and to the quadrature correlations for massless photons demonstrated experimentally using optical parametric down-conversion. We show that for realistic non-uniform condensate models, the proposed matter-wave quadrature measuments have to rely on mode-matched local oscillators. Our model takes into account molecular condensate depletion, s-wave scattering interaction and possible one-body losses of atoms and molecules. An experimental realization of this proposal, which can in principle be achieved via optical Raman transitions or using a magnetic Feshbach resonance, would be a test of fundamental quantum mechanics with massive particles in a mesoscopic regime. [1] K. V. Kheruntsyan, M. K. Olsen, and P. D. Drummond, cond-mat/0407363. [Preview Abstract] |
Thursday, May 19, 2005 10:54AM - 11:06AM |
F4.00003: Continuous Measurement of the 133 Cs Clock Transition Pseudo-spin Souma Chaudhury, Greg Smith, Kevin Schultz, Poul Jessen We demonstrate a weak continuous measurement of the pseudospin associated with the clock transition in a sample of laser cooled Cs atoms. Our scheme uses an optical probe tuned near the D1 transition to measure the sample birefringence, which is proportional to the population in one of the clock states and therefore provides information about the z component of the collective pseudospin. For proper probe polarization and frequency the differential light shift of the clock states vanishes and the measurement becomes non-demolition, at least on timescales short compared to optical pumping due to the scattering of probe photons. The measurement performance is comparable to that seen in Faraday measurements of spin-angular momenta, and is in excellent agreement with our theoretical models. In optically dense samples the measurement sensitivity can be high enough to allow backaction-induced squeezing, which suggests potential applications in the improvement of atomic clocks and atom interferometers. [Preview Abstract] |
Thursday, May 19, 2005 11:06AM - 11:18AM |
F4.00004: Pulse chirping in mode selective excitation Svetlana Malinovskaya The theory of coherent control of molecular vibrations using ultrafast chirped laser pulses in stimulated Raman spectroscopy is investigated. Nonadiabatic and adiabatic pulse interactions with molecules are considered, with the goal of achieving selective excitation of energetically close Raman transitions. A model of two-level systems interacting with transform-limited pump and chirped Stokes pulse is used. Methods for creating a desired coherent superposition of states is analyzed within a dressed state picture. [Preview Abstract] |
Thursday, May 19, 2005 11:18AM - 11:30AM |
F4.00005: Designing Molecular Eigenstates in a Four-level Lambda System Teodora Kirova, Frank Spano, A. Marjatta Lyyra The interaction of single c.w. laser (coupling) field with a four-level lambda system containing two closely spaced upper levels (a and b) is studied as a means to attain quantum control. By adjusting the coupling field Rabi frequency and detuning, it is possible to create a target state of a prescribed admixture of a and b within the dressed state representation. We prove that the design of such a state requires a certain relation between the Rabi frequency and the detuning of the coupling laser, expressed by a specific ``control'' equation. We further show how the creation of the target eigenstate is revealed through the optical absorption spectrum. Electromagnetically induced transparency of an additional probe beam is also studied. The four-level lambda system gives rise to generally two dark resonances for a given coupling field detuning. [Preview Abstract] |
Thursday, May 19, 2005 11:30AM - 11:42AM |
F4.00006: A Bose-Einstein Condensate in a Box Todd Meyrath, Chih-Sung Chuu, James Hanssen, Gabriel Price, Florian Schreck, Mark Raizen We report experimental progress towards the quantum control of individual atoms from a Bose-Einstein condensate. Our system consists of a single one-dimensional BEC of rubidium-87 that is optically trapped in a crossed pair of Hermite-Gaussian TEM01 mode beams. Each beam is tightly focused in one direction and elongated in the other. The overlap of the two beams creates a narrow dark tube with mean transverse oscillation frequencies of 40kHz, comparable to what is obtained with optical lattices, but with a single condensate instead of many replicas. Axial confinement in our trap is provided by Gaussian beam end-caps producing a ``particle-in-a-box'' type geometry. At the smallest measured numbers of 300 atoms, we observe fragmentation of the condensate and have determined that it is due to slight variations in the optical potential along the axial direction. We have implemented an optical compensation scheme to flatten the axial potential. We have demonstrated single atom detection with nearly unit quantum efficiency and this setup is fully integrated with the new trap, paving the way for direct measurements of quantum atom statistics. [Preview Abstract] |
Thursday, May 19, 2005 11:42AM - 11:54AM |
F4.00007: Quantum Transport of a Bose Einstein Condensate Hrishikesh Kelkar, Braulio Gutierrez-Medina, Kevin Henderson, Mark Raizen We report progress on experiments to study many-body quantum transport and dynamics in one-dimensional potentials. Our system consists of a Bose-Einstein Condensate (BEC) of sodium atoms confined to a hybrid magnetic/optical trap. Transverse confinement is provided by a 2-D axially symmetric magnetic trap with a trap frequency of 317 Hz. The BEC is confined axially by a focused YAG laser beam, or by two focused spots that are separated by a controlled distance, creating an optical box. The atoms are then released into an optical potential along the axial direction that is created by an array of far detuned laser spots. Each spot can be independently controlled both in position and power, with a spatial resolution of 6$\mu $m. This potential can be combined with a standing wave that is aligned along the trap axis, enabling transport measurements in potentials that can range from periodic to disordered. [Preview Abstract] |
Thursday, May 19, 2005 11:54AM - 12:06PM |
F4.00008: Quantum-optical spacetime coordinate frames and Compton acceleration William Harter By carefully re-examining some details of quantum and classical optical wave interference, it is possible to give an elegant and transparent redevelopment of relativity and quantum theory in a few simple lines and figures. The key is to let optical coherent states provide spacetime coordinate frames, a kind of quantum GPS. Understanding of quantum coordinate frames, such as Casimir rotors used in molecular and nuclear theory, benefit as well from a more thorough examination of wave mechanics. Geometry of Compton effects and other optical processes are quite revealing and suggest ways to make wave nets of constant acceleration using optical elements of constant velocity. [Preview Abstract] |
Thursday, May 19, 2005 12:06PM - 12:18PM |
F4.00009: Constraints for quantum logic arising from conservation laws and field fluctuations Julio Gea-Banacloche, Masanao Ozawa We explore the connections between the constraints on the precision of quantum logical operations that arise from a conservation law, and those arising from quantum field fluctuations. We show that the conservation-law based constraints apply in a number of situations of experimental interest, such as Raman excitations, and atoms in free space interacting with the multimode vacuum. We also show that for these systems, and for states with a sufficiently large photon number, the conservation-law based constraint represents an ultimate limit closely related to the fluctuations in the quantum field phase. [Preview Abstract] |
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