Bulletin of the American Physical Society
Joint Spring 2010 Meeting of the Texas Sections of the APS, AAPT, and SPS
Volume 55, Number 3
Thursday–Saturday, March 18–20, 2010; Austin, Texas
Session C3: Atomic, Molecular, and Optical Physics I |
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Chair: David Wolf, Austin Community College Room: Robert Lee Moore Hall 5.104 |
Friday, March 19, 2010 10:30AM - 10:42AM |
C3.00001: Frequency-Domain Streak Camera for Ultrafast Imaging of Evolving Light-Velocity Objects Zhengyan Li, Rafal Zgadzaj, Xiaoming Wang, Stephen Reed, Yang Zhao, Michael Downer We demonstrate a frequency-domain streak camera (FDSC) that captures the picosecond evolution of luminal velocity refractive index structures in a single shot. In FDSC, a probe-reference pulse pair propagates obliquely to an evolving index structure generated by a pump pulse in glass, supplementing a conventional frequency-domain holographic (FDH) probe-reference pair that co-propagates with the pump. A single spectrometer acquires data from both probes via spatial or temporal multiplexing, demonstrating the possibility of frequency-domain tomography (FDT) in which a single spectrometer processes data from over a dozen of probing angles. [Preview Abstract] |
Friday, March 19, 2010 10:42AM - 10:54AM |
C3.00002: Observation of Optical Bullets formed in Laser-driven Plasma Bubble Accelerators P. Dong, S.A. Reed, S.A. Yi, S. Kalmykov, G. Shvets, N.H. Malis, C. McGuffey, S.S. Bulanov, V. Chvykov, G. Kalintchenko, K. Krushelnick, A. Maksimchuk, T. Matsuoka, A.G.R. Thomas, V. Yanovsky, M.C. Downer Laser-driven plasma ``bubble'' electron accelerators, a nonlinear regime of the laser wakefield accelerator, have produced collimated, nearly mono-energetic relativistic electron beams up to 1 GeV energy in millimeter acceleration lengths. To date the bubble's spatio-temporal structure has been accessible only from intensive computer simulations based on estimated initial conditions. Here we demonstrate direct, non-invasive, single-shot visualization of bubbles in plasmas of density n$_{e} \quad >$ 10$^{19}$ cm$^{-3}$, whether or not the bubbles produce relativistic electrons, by observing ``bullets'' of light that the bubble trap, focus and compress from co-propagating probe pulses. We correlate these bullets with relativistic electrons that the bubble captured and accelerated. Frequency Domain Holography (FDH),used previously to visualize weakly nonlinear sinusoidal wakes in plasmas of density n$_{e} \quad <$ 0.6 $\times $ 10$^{19}$ cm$^{-3}$, are tweaked to work in this high density regime. [Preview Abstract] |
Friday, March 19, 2010 10:54AM - 11:06AM |
C3.00003: Isotope Separation Using Single-Photon Atomic Sorting Melissa Jerkins, Isaac Chavez, Mark Raizen Isotope separation is one of the grand challenges of modern society and holds great potential for basic science, medicine, energy, and defense. We present a new and general approach to isotope separation. The method is based on an irreversible change of the mass-to-magnetic moment ratio of a particular isotope in an atomic beam, followed by deflection in a magnetic field gradient. We numerically simulate isotope separation for a range of examples. The first class of atoms we consider are those that have zero magnetic moment in their ground electronic state. A laser induces an irreversible transition to a metastable state, followed by magnetic deflection. The second (larger) class of atoms we consider are those that have a magnetic moment in their ground state. The magnetic stretch-state is deflected in one zone of a magnetic field gradient, followed by a laser excitation that lowers the magnetic moment of a particular isotope. Those atoms are then separated in a second field gradient zone. We show that the efficiency of the process is only limited by the available laser power, since one photon on average enables the separation of one atom. [Preview Abstract] |
Friday, March 19, 2010 11:06AM - 11:18AM |
C3.00004: Towards the creation of atomic Fock states David Medellin, Gabriel Price, Kirsten Viering, Jianyong Mo, Mark Raizen Atomic Fock states provide ideal initial conditions to study few-body atomic physics. Recently, our group proposed and demonstrated the method of ``laser culling'', achieving sub-Poissonian atom number statistics in a degenerate bosonic gas. We propose a new approach using fermionic Lithium 6, where a theoretical analysis has demonstrated the prospect of producing an atom ``on demand'' with ultra-high fidelity. A new experimental setup is being built towards this end and the current status of the experiment is discussed. [Preview Abstract] |
Friday, March 19, 2010 11:18AM - 11:30AM |
C3.00005: Single-photon cooling in an rf-dressed magnetic trap Travis Bannerman, Edvardas Narevicius, Mark Raizen The cooling and trapping of atoms in the gas phase has been a major theme of physics research in the last several decades. Progress has largely been enabled by the development of laser cooling techniques, which, though powerful, have been successfully implemented with only a handful of atomic species. Our group has recently demonstrated a general cooling technique that, by requiring the scattering of only a single photon, circumvents the restrictions inherent in traditional laser cooling techniques. The efficiency of the cooling was shown to be limited only by the dynamics of the initially trapped atoms. Here we show how the cooling efficiency may be improved with the use of an rf-dressed magnetic trap, with final temperatures approaching the recoil temperature. We outline the implementation of single-photon cooling for hydrogen, an atom which cannot be cooled with traditional techniques. We also consider the application of single-photon cooling to molecules. [Preview Abstract] |
Friday, March 19, 2010 11:30AM - 11:42AM |
C3.00006: Toward magnetic trapping of isotopes of hydrogen Robert Clark, Adam Libson, S. Travis Bannerman, Thomas Mazur, Isaac Chavez, Mark Raizen Over the past decades, spectroscopy of atomic hydrogen has enabled precision measurements of many fundamental physical quantities. Today, the trapping of hydrogen and its isotopes remains an important goal in physics. One promising technique for obtaining such samples is magnetic deceleration of a supersonic beam, via an ``atomic coilgun.'' In this work, we present progress toward magnetically trapping deuterium in a simple room-temperature apparatus, which includes the coilgun and a solid-state laser system for addressing the 1S-2S transition. We also discuss prospects for cooling samples of hydrogen, deuterium, and tritium through the recently discovered technique of single-photon cooling. [Preview Abstract] |
Friday, March 19, 2010 11:42AM - 11:54AM |
C3.00007: Trapping of Silica Microspheres in Air and Vacuum using Counter-Propagating Optical Tweezers Simon Kheifets, Tongcang Li, David Medellin, Mark G. Raizen We have used counter-propagating dual-beam optical tweezers to trap micron-scale Silica spheres in air and vacuum and observe their motion at microsecond and sub-Angstrom scales. This has allowed for detailed study of Brownian motion and precise measurements of fluid-particle interactions. There has been growing interest in cooling of mechanical modes of high Q resonators towards ground-state levels, which is usually limited by coupling of the resonator to a warmer thermal reservoir. When in vacuum, our bead is completely thermally isolated and represents an ideal candidate for ground-state cooling and ultimately for use as an ultra-sensitive detector operating at the quantum limit. [Preview Abstract] |
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