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 U3: Atomic, Molecular, and Nanoparticle Structure and Properties |
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Chair: Carol Tanner, University of Notre Dame Room: A703 |
Friday, June 17, 2011 10:30AM - 10:42AM |
U3.00001: Improved Polarizabilities of Th$^{4+}$ from microwave spectroscopy of Th$^{3+}$ Rydberg levels Julie Keele, Stephen Lundeen, Charles Fehrenbach The dipole and quadrupole polarizabilities of Rn-like Th$^{4+}$ were recently measured using the optical Resonant Excitation Stark Ionization Spectroscopy (RESIS) method [1]. With this method, a Doppler-tuned CO$_{2}$ laser excites high-L Rydberg levels of Th$^{3+}$ to a much higher Rydberg level that can be detected by Stark ionization, and the polarizabilities are revealed by the fine structure pattern resolved in the laser excitation. Much improved precision can be obtained with the RESIS/Microwave technique [2] in which direct transitions between high-L levels of the same principal quantum number are induced by RF or microwave fields and detected by their effect on the optical RESIS signals. We will report on progress using this technique to improve the determinations of the Th$^{4+}$ polarizabilities.\\[4pt] [1] M.E. Hanni, et. al., Phys. Rev. A \underline {82}, 022512 (2010)\\[0pt] [2] M.E. Hanni, et. al., Phys. Rev. A \underline {78}, 062510 (2008) [Preview Abstract] |
Friday, June 17, 2011 10:42AM - 10:54AM |
U3.00002: Polarizability measurements of the ground and metastable states of Sr, Yb, and Ba William Holmgren, Ivan Hromada, Catherine Klauss, Vincent Lonij, Alex Cronin We report progress towards 0.1{\%} measurements of the DC polarizabilities of strontium, ytterbium, and barium in the ground 1S0 and metastable 3P0 states. We use a Mach-Zehnder atom interferometer with an electric field gradient to perform these measurements. Since our beam splitters are species-independent nanogratings, we can eliminate many systematic errors by performing ratio measurements with respect to a better-known polarizability (e.g. $\alpha _{\mbox{Sr}} /\alpha _{\mbox{Li}} )$. These measurements will reduce uncertainty in optical clocks and provide new benchmark tests for atomic structure calculations. [Preview Abstract] |
Friday, June 17, 2011 10:54AM - 11:06AM |
U3.00003: Up-down asymmetry of the electrons ejected from barium $6p_{1/2}nk$ autoionizing states Jirakan Nunkaew, Tom Gallagher The Ba $6p_{1/2}nk$ autoionizing Stark states do not have well-defined parities but have the Rydberg electrons localized in the upfield or downfield side of the atom. As a result when they autoionize the angular distributions of ejected electrons are not up/down symmetric with respect to the laser polarization direction. In this experiment, we measure the ejected electron signals from Ba $6p_{1/2}nk$ autoionizing Stark states, of n=28 and 29, produced by linearly polarized laser excitation in weak electric fields of less than 15 V/cm. In the weak electric field region, the energy gained by the ejected electrons is comparable to the initial energy of the ejected electron. This makes the observation of the up/down asymmetry of the ejected electrons possible. We observe that the electrons from Ba $6p_{1/2}nk$ autoionizing red states are ejected preferentially in the upfield direction while the electron from Ba $6p_{1/2}nk$ autoionizing blue states are ejected preferentially in the downfield direction. [Preview Abstract] |
Friday, June 17, 2011 11:06AM - 11:18AM |
U3.00004: Electromagnetically Induced Transparency in the Far-off Resonance Trap of Cs Atoms Chin-Chun Tsai, Zong-Syun He, Sheng-Lung Lin, Yung-Yung Chang In this experiment, electromagnetically induced transparency\,(EIT) in the far-off-resonance optical trap of Cs atoms is investigated. The optical trap is generated by an Nd:YAG laser\,(1064\,nm) of laser power 3.4 W, and beam waist 150 \,$\mu$m with the trap depth about 70\,$\mu$K and is trapped about $2.6\times10^5$ atoms. The cascade EIT is operated with two counter-propagating beams, probe and coupling, which are superimposed on the optical trap with the size of coupling beam slightly larger than the probe beam. The probe laser is at transition from $|6S_{1/2},\,F=4\rangle$ to $|6P_{3/2},\,F=5\rangle$ and the coupling laser is from $|6P_{3/2},\,F=5\rangle$ to $|8S_{1/2},\,F=4\rangle$. The frequency of probe laser is stabilized and fixed while frequency of the coupling laser is scanned through the resonance of $6P_{3/2}$ to $8S_{1/2}$. A numerical simulation by solving the steady state density matrix fits well with the experimental profile. [Preview Abstract] |
Friday, June 17, 2011 11:18AM - 11:30AM |
U3.00005: Causes of power broadening in EIT intensity noise spectroscopy Michael Crescimanno, Charles Snider, Shannon O'Leary EIT noise spectroscopy is a potentially promising way to simplify magnetometer design. One technically fortuitous characteristic of this intensity noise spectroscopy is the non-power broadening behaviour. We describe quantum optics theory applied to more realistic models of EIT systems that explain the existence and range of this power broadening-free regime. [Preview Abstract] |
Friday, June 17, 2011 11:30AM - 11:42AM |
U3.00006: Anti-Relaxation Coatings at High Magnetic Field Ben Olsen, Will Happer, Brian Patton, Dmitry Budker, Mikhail Balabas Polarized alkali metal vapors are the basis for many technologies and experiments in atomic physics such as magnetometers, atomic clocks, precision measurements and spin exchange optical pumping (SEOP). These applications all rely on long relaxation times of the populations and coherences in the vapor, and considerable effort has been spent developing techniques to extend these times. The significant relaxation due to the glass walls of vapor cells can be drastically reduced by applying a coating of organic molecules such as paraffin to the cell's interior. To study the effects of anti-relaxation coatings on alkali vapors, we measured the ground-state populations of cesium vapor in coated vapor cells at high magnetic field. In this regime, each ground-state sublevel population can be individually measured with a weak D1 $(S_{1/2}\rightarrow P_{1/2})$ laser while a stronger D2 $(S_{1/2}\rightarrow P_{3/2})$ laser depopulates a single sublevel. We physically translated the probe beam to measure the populations at different distances from the wall of the vapor cell, over a range of pump laser frequencies. We also measured the longitudinal relaxation rates of the cesium populations in the coated vapor cells by monitoring absorption of the probe while modulating the pump laser intensity. [Preview Abstract] |
Friday, June 17, 2011 11:42AM - 11:54AM |
U3.00007: Investigation of hyperfine clock resonances in alkali-vapor cells with novel antirelaxation surface coating Eric Corsini, Todor Karaulanov, Mikhail Balabas A recently identified alkene based antirelaxation coating for alkali-metal vapor cells has enabled demonstration of ground-state polarization times in excess of a minute, which is two orders of magnitude longer than with conventional paraffin coatings.\footnote{M.V. Balabas, T Karaulanov, M.P. Ledbetter, and D. Budker, Phys. Rev. Lett. \textbf{105}, 070801 (2010)} This narrow resonance combined with vapor cells short term stability and compact size, spurs a renewed interest in application of coated cells to secondary frequency standards, and raises new questions as to the mechanisms underlying wall-collision induced relaxation. We will present a systematic study of hyperfine transition widths and shifts and compare them to those in cells coated with paraffin. [Preview Abstract] |
Friday, June 17, 2011 11:54AM - 12:06PM |
U3.00008: Precision Laser Transmission Spectroscopy: Applications to Nanoparticle Systems Carol Tanner, Frank Li, Ching-Ting Hwang, Robert Schafer, Steven Ruggiero We describe the implementation of precision laser transmission spectroscopy (LTS) for determining the size, shape, and number of nanoparticles in suspension. Our apparatus incorporates a tunable laser and balanced optical system, which measures light transmission over a wide wavelength range (210-2300 nm) with high precision and sensitivity. Spectral inversion is employed to determine both the particle size distribution and the absolute number density of particles ranging in diameter from 5 to 3000 nm with $\sim $3 nm resolution. With respect to density, the sensitivity or our measurement system ranges from $\sim $1000 particles/mL up to 10$^{10}$ particles/mL (5x10$^{-8}$ vol.{\%} to 0.5 vol. {\%}). The size range of applicability is comparable to that of dynamic light scattering (DLS) but with approximately six orders of magnitude higher sensitivity and five times the resolution. The technique also allows us to determine the length and width of rod shaped particles including biological objects. Currently, LTS is being applied as a tool to investigate various biological and non-biological nanoparticle systems including: metals, oxides, carbon, organic materials, proteins, viruses, bacteria, liposomes, DNA, etc. We acknowledge the support of the University of Notre Dame Office of the Vice President for Research and NDnano/MIND. [Preview Abstract] |
Friday, June 17, 2011 12:06PM - 12:18PM |
U3.00009: Wheeler-Feynman absorber revisited: a useful technique to calculate decay rates and lifetimes in small scale optical systems Murugesan Venkatapathi The Wheeler-Feynman (WF) absorber theory of radiation though no more of interest in explaining self interaction of an electron, can be very useful in today's research in small scale optical systems. The significance of the WF absorber is the use of time-symmetrical solution of Maxwell's equations as opposed to only the retarded solution. The radiative coupling of emitters to nano wires in the near field and change in their lifetimes due to small mode volume enclosures have been elucidated with the retarded solutions before. These solutions have also been shown to agree with quantum electrodynamics, thus allowing for classical electromagnetic approaches in such problems. It is here assumed that the radiative coupling of the emitter with a body is in proportion to its contribution to the classical force of radiative reaction as derived in the WF absorber theory. Representing such nano structures as a partial WF absorber acting on the emitter makes the computations considerably easier than conventional electromagnetic solutions for full boundary conditions. [Preview Abstract] |
Friday, June 17, 2011 12:18PM - 12:30PM |
U3.00010: ABSTRACT WITHDRAWN |
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