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 K3: Undergraduate Research Session |
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Chair: Eric Wells, Augustana College, Sioux Falls Room: Keller Building 104 |
Thursday, May 29, 2008 2:00PM - 2:20PM |
K3.00001: Precise measurement of the hyperfine splittings within the 6p$_{3/2}$ level of atomic indium using two-color diode laser spectroscopy Invited Speaker: The hyperfine splittings of the 6P$_{3/2}$ state of indium(I=9/2) have been measured for the first time using a two-color excitation scheme. These results provide a precise experimental test of new \textit{ab initio} wavefunction calculations of three-valence-electron atomic systems such as indium and thallium. We first excite ground-state atoms in a heated quartz indium cell to the intermediate 6S$_{1/2}$ state using a blue (GaN) diode laser at 410 nm. By measuring the differential atomic absorption of double-passed, second-order-diffracted beams from an acousto-optic modulator, we are able to stabilize the blue laser frequency to the sub-MHz level. A second laser beam at 1291 nm overlaps the first in the vapor cell, exciting Doppler-narrowed hyperfine transitions to the 6P$_{3/2}$ excited state. By modulating the blue laser beam and using lock-in detection, we obtain background-free, low-noise IR spectra. By locking first to one then the other intermediate hyperfine level, we determine all three hyperfine splittings, as well as the `A' and `B' hyperfine constants, for the 6P$_{3/2 }$excited state. While we continue to explore many potential systematic errors, current statistical precision is at the few MHz level, and preliminary results show very good agreement with theory predictions at this level. [Preview Abstract] |
Thursday, May 29, 2008 2:20PM - 2:40PM |
K3.00002: Stabilized 1762 nm Laser for Barium Ion Qubit Readout via Adiabatic Passage Invited Speaker: Trapped ions are one of the most promising candidates for the implementation of quantum computation. We are trapping single ions of Ba$^{137}$ to serve as our qubit, because the hyperfine structure of its ground state and its various visible-wavelength transitions make it favorable for quantum computation. The two hyperfine ground levels will serve as our $\vert $1$>$ and $\vert $0$>$ qubit states. The readout of the qubit will be accomplished by first selectively shelving the ion directly to the metastable 5D5/2 state using a 1762 nm narrow band fiber laser. Next, the cooling and repumping lasers are turned on and the fluorescence of the ion is measured. Since the 5D5/2 state is decoupled from the laser cooling transitions, the ion will remain dark when shelved. Thus if fluorescence is seen we know that the qubit was in the $\vert $0$>$ state, and if no fluorescence is seen it was in the $\vert $1$>$ state. The laser is actively stabilized to a temperature-controlled, high-finesse 1.76 um Zerodur optical cavity. The shelving to the 5D5/2 state is most efficiently achieved with adiabatic passage, which requires a smooth scan of the laser frequency across the transition resonance. To accomplish this, the laser frequency is modulated by an AOM driven by a smooth frequency sweep of adjustable amplitude and duration. [Preview Abstract] |
Thursday, May 29, 2008 2:40PM - 3:00PM |
K3.00003: A Novel Short Extended Cavity Diode Laser for Red Wavelengths Invited Speaker: We present the design and characterization of a short extended cavity diode laser with immediate applications in ultracold atomic physics. To reach wavelengths unavailable in commercial laser diodes, a laser was constructed such that it could be cooled without loss in performance. We demonstrate that this laser design has a mode-hop-free tuning range of 20 GHz or greater when modulating laser current, and that it can also be adjusted using temperature controls and a piezo-electric output coupler mount. We also show that this laser achieves stable single-mode operaction with both 90\% and 50\% reflective output couplers without degrading its performance. Finally, we present an application of this laser as a repumper in cooling and trapping experiments of $^{88}$Sr, including increasing the yield of trapped atoms and studying the lifetimes of metastable atomic states. [Preview Abstract] |
Thursday, May 29, 2008 3:00PM - 3:20PM |
K3.00004: Beam Production and Stabilization via Frequency Up-conversion in Rubidium Vapor Invited Speaker: Two pumping lasers with wavelengths of 776nm and 780nm produce two-step excitation from the ground state of rubidium. These excited atoms undergo a double cascade through the 6P$_{3/2}$ energy state before returning to the ground state. The final transition to the ground state produces a fluorescence of 420nm photons. When the pump lasers are co-propagating and detuned from the resonances, a forward propagating coherent blue beam is observed to emanate from the rubidium vapor cell. The beam is found to be collimated and to have a power up to 15$\mu $W. However, the beam has not yet been extensively characterized due to its relative instability related to the precise tunings of the two pump lasers and the temperature of the rubidium vapor cell. This work discusses the attempts to stabilize, characterize, and model the blue beam that results from this process. In our specific set up, two co-propagating external-cavity diode laser beams at 776 nm and 780 nm are directed through a rubidium vapor cell with a natural isotopic abundance of Rb$^{85}$ and Rb$^{87}$. The power in each beam is approximately 30 mW. The vapor cell is heated via a novel oven design and can be held to a temperature of 25-300$^{o}$C, and the diode lasers are independently tunable through temperature, current, and external cavity gratings. [Preview Abstract] |
Thursday, May 29, 2008 3:20PM - 3:40PM |
K3.00005: Theoretical study of half-cycle pulse assisted ionization and recombination in Rydberg atoms Invited Speaker: We perform a fully quantum-mechanical calculation of the dynamics and ionization of both radial and angular wave packets of a Rydberg electron when kicked by successive terahertz half-cycle pulses (HCPs) in arbitrary directions. We study HCP-assisted recombination and ionization processes experimentally studied by Ziebel and Jones (Phys. Rev. A, \textbf{vol}, pg, (2003)). The wave packets are represented on a nonlinear radial grid, and a truncated angular momentum basis; and the unitary propagation is carried out by an implicit finite-difference method. The HCP interaction is modelled as an impulse, or momentum boost of the wavefunction. We present comparisons of our results with the experimental and classical calculations of Ziebel and Jones. We further investigate the recombination \& ionization of radial \emph{and} angular wavepackets (produced by a first HCP) assisted by a second HCP polarized in an arbitrary direction from the first. [Preview Abstract] |
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