Bulletin of the American Physical Society
39th Annual Meeting of the APS Division of Atomic, Molecular, and Optical Physics
Volume 53, Number 7
Tuesday–Saturday, May 27–31, 2008; State College, Pennsylvania
Session U5: New Experimental Techniques |
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Chair: Marty Ligare, Bucknell University Room: Nittany Lion Inn Boardroom I |
Saturday, May 31, 2008 8:00AM - 8:12AM |
U5.00001: Rubidium atomic hyperfine filter for amplitude manipulation of femtosecond frequency comb Marin Pichler, Hrvoje Skenderovi\' c, Damir Aumiler, Ticijana Ban, Goran Pichler Femtosecond mode-locked laser pulse train excitation in rubidium $5$ $^{2}S_{1/2}\rightarrow5$ $^{2}P_{3/2}$ transition is used for direct mapping of the optical frequency comb to rubidium atom velocity comb. The induced comb-like structure in the rubidium ground state hyperfine level populations is monitored by a weak cw scanning probe laser. By introducing an additional rubidium cell, a hyperfine atomic filter is realized which modifies the amplitude of the selected frequency comb lines. The hyperfine optical filter can be a pure isotope $^{85}$Rb or $^{87}$Rb cell, in which case only that isotope will affect the optical frequency comb. [Preview Abstract] |
Saturday, May 31, 2008 8:12AM - 8:24AM |
U5.00002: Laser frequency comb for improved exoplanet detection and cosmology Chih-Hao Li, Andrew J. Benedick, Peter Fendel, Alex Glenday, Franz X. Kaertner, David F. Phillips, Dimitar Sasselov, Andrew Szentgyorgyi, Ronald L. Walsworth Searches for extrasolar planets using the periodic Doppler shift of stellar lines are approaching Earth-like planet sensitivity. To find a 1-Earth-mass planet in an Earth-like orbit, an order of magnitude improvement in state-of-the-art radial velocity spectroscopy is necessary. An approach that combines a laser frequency comb with a Fabry-Perot cavity has been suggested as a promising avenue to improved wavelength calibration. Here we report the fabrication of such a laser comb with up to 40 GHz ($\approx 1\ \AA$) line-spacing, without compromise of long-term stability, reproducibility or spectral resolution and that is well matched to the resolving power of high-resolution astrophysical spectrographs. The instrument will be deployed on the MMT in May 2008 to calibrate the Hectochelle spectrograph in a demonstration project to search for dark matter in globular clusters and in 2009/10 at the HARPS clone spectrograph on the William Herschel telescope to search for exoplanets. [Preview Abstract] |
Saturday, May 31, 2008 8:24AM - 8:36AM |
U5.00003: Spin-Exchange Optical Pumping of Alkali Salts Ben Olsen, Brian Patton, Yuan-Yu Jau, Will Happer, Kiyoshi Ishikawa Spin-Exchange Optical Pumping (SEOP) is a technique used to polarize nuclei in excess of their equilibrium limit. SEOP is achieved by optically pumping an alkali vapor which then transfers angular momentum to the nuclei of interest. We have recently hyperpolarized $^{133}$Cs nuclei in solid CsH using SEOP, achieving magnetizations more than an order of magnitude larger than the thermal equilibrium value.\footnote{Ishikawa \emph{et. al.}, Phys. Rev. Lett. {\bf 98}, 183004 (2007)} In subsequent work, we investigate the mechanisms underlying this transfer of angular momentum. By optically pumping Cs vapor with laser light resonant with several optical transitions, each yielding different nuclear and electronic spin currents to the solid, we attempt to determine the source of transferred angular momentum. Early evidence suggests both electronic and nuclear spin polarization in the vapor contribute to $^{133}$Cs nuclear polarization in the salt. The $^1$H polarization is also mildly affected by optical pumping. We compare these results to numerical simulations and to results from other alkali salts. Further studies are warranted to discover if polarization can be transferred to other nuclei (e.g., alkali salts) on the cell walls. [Preview Abstract] |
Saturday, May 31, 2008 8:36AM - 8:48AM |
U5.00004: Laser-Atomic Oscillator Yuan-Yu Jau, William Happer We report a newly developed technique, laser-atomic oscillator, for simultaneously generating stable optical and electrical modulations with a very few components. It requires only a semiconductor laser, a vapor cell, and a few optical components. No photodetector and electronic feedback are needed. In this new system, the ground-state hyperfine coherence of alkali-metal atoms is spontaneously generated. The modulated laser light with a spectrum of a small optical comb is automatically produced, and the spacing between the comb peaks is photonically locked to the hyperfine frequency. The charge carriers in the semiconductor laser are also modulated at the hyperfine frequency. Laser-atomic oscillator is purely optical. Its simple structure allows the system to be very compact. We believe this new technique will bring some advantages in the applications of atomic chronometry, atomic magnetometry, and generation of multi-coherent light. [Preview Abstract] |
Saturday, May 31, 2008 8:48AM - 9:00AM |
U5.00005: Polarization of metastable 129Xe Tian Xia, Steven Morgan, Yuan-Yu Jau, William Happer We have measured atomic polarization of metastable 129Xe in a pyrex cell by optical pumping, while metastability exchange optical pumping of 3He is routinely done. The atomic polarization of metastable Xe is on the order of 10{\%}. Metastable xenon is created by electrodeless rf discharge. The hyperfine transition of metastable 129Xe is observed by microwave excitation. Atomic polarization can be demonstrated by comparison of the intensities of the transitions between different Zeeman sublevels, while pumping a specific optical transition of metastable Xe with circularly polarized light. This work offers insight into attempts to polarize 129Xe nuclei by metastability exchange optical pumping. [Preview Abstract] |
Saturday, May 31, 2008 9:00AM - 9:12AM |
U5.00006: Slowing and Stopping Supersonic Beams with an Atomic Coilgun Adam Libson, Edvardas Narevicius, Christian G. Parthey, Isaac Chavez, Julia Narevicius, Uzi Even, Mark G. Raizen We report the stopping of a supersonic beam of metastable neon using an atomic coilgun. The coilgun relies on the Zeeman effect, and uses pulsed magnetic fields of up to 5.2 T to bring atoms from 446 m/s to near rest. Additionally, we have implemented the coilgun to slow a supersonic beam of molecular oxygen from 458 m/s to 238 m/s. This method can be applied to stop and trap any paramagnetic atom or molecule. Future applications will be discussed. [Preview Abstract] |
Saturday, May 31, 2008 9:12AM - 9:24AM |
U5.00007: Detecting level crossings without looking at the spectrum M. Bhattacharya, C. Raman Crossings and avoided crossings are a ubiquitous phenomenon in physics, and are associated with many important physical effects such as Berry's phase, Feshbach resonances and quantum chaos. We present an algebraic technique to detect level crossings which does not require the solution or complete knowledge of the Hamiltonian of the system [1,2,3]. Details of the method, including a novel way to visualize crossings, will be presented using the simple example of a ground state hydrogen atom in a magnetic field [4]. \newline \newline [1] M. Bhattacharya and C. Raman, Phys. Rev. Lett. \textbf{97}, 140405-1 (2006). \newline [2] M. Bhattacharya and C. Raman, Phys. Rev. A, \textbf{75}, 033405-1 (2007). \newline [3] M. Bhattacharya and C. Raman, Phys. Rev. A, \textbf{75}, 033406-1 (2007). \newline [4] M. Bhattacharya, Am. J. Phys., \textbf{75}, 942 (2007). [Preview Abstract] |
Saturday, May 31, 2008 9:24AM - 9:36AM |
U5.00008: ABSTRACT WITHDRAWN |
Saturday, May 31, 2008 9:36AM - 9:48AM |
U5.00009: Monitoring coherent vibrational control with transient multidimensional infrared spectroscopy. Matthew Ross, Kevin Kubarych Multidimensional infrared (MDIR) Fourier transform spectroscopy is a powerful experimental technique to relieve spectral congestion, revealing coherence transfer, energy relaxation, and coupling between states. Using novel non-equilibrium, transient MDIR sequences we monitor the effects of high vibrational excitation $(v>2)$ on intramolecular dynamics and system-bath interactions. MDIR spectroscopy offers a structurally sensitive probe of coherent control enabling a more detailed molecular interpretation of control mechanisms. A phase shaped, high-energy IR control pulse is timed to arrive either before or during a three-pulse echo sequence. We investigate the spectral phase dependence of this control pulse on the evolving MDIR spectrum in a system of strongly coupled CO oscillators in metal carbonyls. A key goal is controlling ground electronic state dynamics by exciting the system with optical excitation that pushes beyond the perturbative limit in order to enhance or suppress specific transitions in analogy to NMR spectroscopy. [Preview Abstract] |
Saturday, May 31, 2008 9:48AM - 10:00AM |
U5.00010: Detection and Imaging of $\rm{He}_2$ Triplet Molecules in Superfluid Helium W.G. Rellergert, S.B. Cahn, A. Curioni, J.A. Nikkel, J.D. Wright, D.N. McKinsey We present new results on the detection and imaging of $\rm{He}_2$ triplet molecules in superfluid helium using laser-induced fluorescence. A two photon transition at 905 nm results in the emission of a single detectable photon of shorter wavelength (640 nm). This cycling transition can be driven many times over the course of the molecule lifetime (13 s). New lasers with higher repetition rates and average powers have allowed us to study the efficiency of the transition as the cycling rate is increased. Results of these studies and their implications for detecting and imaging individual molecules are discussed. This technique has potential applications in the detection of gamma rays, WIMP dark matter, and ultracold neutrons, as well as the three-dimensional imaging of fluid flow and vortices in superfluid helium. [Preview Abstract] |
Saturday, May 31, 2008 10:00AM - 10:12AM |
U5.00011: Laser Induced Electron Diffraction A. Staudte, M. Meckel, D. Comtois, D. Zeidler, D. Pavicic, H. Bandulet, H. Pepin, J.C. Kieffer, R. Doerner, D.M. Villeneuve, P.B. Corkum If a molecule is subjected to a strong, infrared laser field usually an electron from the Highest Occupied Molecular Orbital (HOMO) will tunnel into the continuum. Due to the oscillating laser field a temporally confined electron wavepacket is created and quickly accelerated away from the parent ion. However, some portion of this electron wavepacket will be swept back over the parent molecule once before departing. This laser driven electron scattering off its parent molecule is believed to be a useful method to determine molecular structure through electron diffraction. We have used COLTRIMS to measure the three-dimensional electron momentum distribution of aligned O$_2$ and N$_2$ molecules singly ionized by an intense laser pulse. We find that the low energy part of the electron spectrum carries the fingerprint of the HOMO. In the high energy part of the 3D electron spectrum we identify the first fingerprint of laser induced electron diffraction. Using a simple classical trajectory model we achieve a good agreement with the experiment. The method can be possibly extended to more complex molecules since the interference fringes are largely insensitive to the symmetry of the HOMO of the molecule and thus only reflect the internuclear separation. [Preview Abstract] |
Saturday, May 31, 2008 10:12AM - 10:24AM |
U5.00012: Analysis of a single pulse of light through a Fabry-P\'{e}rot interferometer J. Bruce Johnson, Kevin Lyon, Michael J. Johnson We present a method of analyzing the output of a single pulse of light from a Fabry-P\'{e}rot interferometer. Together with an independent measurement of the pulsewidth the analysis enables the determination of the linewidth, time-bandwidth product, and consequently the degree of coherence of the pulses. The method presented is ideal for light pulses longer than a picosecond where analysis with a FROG is difficult. The analysis presented builds on the method presented by Marzenell, Beigang, and Wallenstein by analyzing the ring pattern of the Fabry-P\'{e}rot interferometer. S. Marzenell, R. Beigang, R. Wallenstein, Appl. Phys. B \textbf{71}, 185 -- 191 (2000). [Preview Abstract] |
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