Bulletin of the American Physical Society
41st Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 55, Number 5
Tuesday–Saturday, May 25–29, 2010; Houston, Texas
Session W5: Laser Cooling and Trapping |
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Chair: Dan Heinzen, University of Texas at Austin Room: Arboretum I-III |
Saturday, May 29, 2010 8:00AM - 8:12AM |
W5.00001: Towards Laser trapping of Argon-39 - A Spectroscopic Study of the Metastable Cycling Transition at 811.8 nm William Williams, Zheng-Tian Lu, Kenneth Rudinger, Chenyu Xu, Reika Yokochi, Peter Mueller Phase-modulation saturation spectroscopy is performed on an enriched radioactive Ar-39 sample. The spectrum of the metastable cycling transition at 811.8 nm is recorded, and its isotope shift between Ar-39 and Ar-40 is derived. The hyperfine coupling constants A and B for both the lower and upper states of the transition are also determined. Atomic structure information of this transition is needed in order to implement Atom Trap Trace Analysis (ATTA) of this rare isotope for applications in the earth sciences. This work is supported by DOE, Office of Nuclear Physics under contract No. DE-AC02-06CH11357. [Preview Abstract] |
Saturday, May 29, 2010 8:12AM - 8:24AM |
W5.00002: Engineering trapping potentials for ultracold polar molecules Svetlana Kotochigova We study the dynamic polarizability (Stark shift) of ultracold polar molecules due to the combined effect of a trapping laser and an external electric field. We found that the polarizability depends on the relative orientation of these fields. In fact, the relative orientation can influence the geometry of the trapping potential and thus collisional properties of the molecules. Moreover, at a particular orientation, a so called ``magic angle,'' the trapping potential is insensitive to the external fields. Inspite of the fact that no ``magic frequency'' is found in the optical domain between various rotational states of a number of ground state polar molecules at zero electric field, there exist ``magic electric field'' values, where the Stark shifts can be made equal. [Preview Abstract] |
Saturday, May 29, 2010 8:24AM - 8:36AM |
W5.00003: Multi-Photon Magneto-Optical Trapping Roger Brown, Saijun Wu, Thomas Plisson, William Phillips, J.V. Porto We demonstrate a Magneto-Optical Trap (MOT) configuration which employs optical forces due to light scattering between two electronically excited states of Cesium. A multi-photon cooling mechanism allows for the replacement of standard MOT beams in up to 4 of the usual 6 directions with MOT beams connecting~excited to further excited states. The multi-photon mechanism creates cooling and trapping on both red and blue sides of the two-photon resonance. The new configuration also exhibits many of the same experimentally appealing features found in a standard MOT including: efficient capture from a vapor cell, densities approaching 10$^{11}$ atoms per cubic cm and sub-Doppler temperatures. Operating this multi-photon MOT in a far single photon detuned regime, we observe sub-Doppler temperatures on the blue side of two photon resonance indicating a fundamentally different two color polarization gradient cooling effect. Possible applications of this MOT are improved single-atom detection by efficiently collecting fluorescence along the path of the excited MOT beams, using optical filters to separate the fluorescence from the trapping light, and the ability to trap new species with inconvenient laser wavelengths by relaxing power requirements on the MOT beams. PRL 103, 173003 [Preview Abstract] |
Saturday, May 29, 2010 8:36AM - 8:48AM |
W5.00004: Capture of a continuous beam of Li atoms in a cryogenic, supersonic helium jet. Michael Borysow, Brady Stoll, Daniel Heinzen We are developing an intense cold atom source based on continuous post-nozzle injection of lithium atoms into a supersonic helium jet. The jet operates at a temperature of 5 Kelvin and with a continuous flux of approximately$10^{20}$ helium atoms per second, corresponding to a helium phase space density of order $10^{-3}$. By adiabatic expansion, the temperature in the moving frame will be reduced into the mK regime. Lithium atoms injected into the beam will become entrained in the helium flow, and subsequently extracted from it with a magnetic lens. Numerical simulations show that high efficiency of capture and extraction may simultaneously be realized. We anticipate that the extracted lithium beam will have a brightness that is substantially larger than what can be achieved with laser-cooling. We have completed studies of the capture of Li atoms by the helium jet with laser-induced fluorescence. The fluorescence images show clear evidence of entrainment of the Li atoms. [Preview Abstract] |
Saturday, May 29, 2010 8:48AM - 9:00AM |
W5.00005: Cooling Atoms with a Moving One-Way Barrier Elizabeth Schoene, Jeremy Thorn, Daniel Steck We demonstrate the use of a moving optical one-way barrier for cooling a collection of atoms. In our experiment, rubidium atoms begin in a far-detuned dipole trap consisting of a single focused Gaussian beam. Two laser beams transversely cross the trap; one provides a repulsive (attractive) potential for atoms in the upper (lower) ground state, and the other pumps atoms into the upper ground state on one side of the first beam, forming a one-way barrier. The optical one-way barrier is adiabatically swept along the longitudinal axis of the trap. At each point, the barrier traps atoms near their turning point, where they have less kinetic energy. As the barrier sweeps, the atoms do not regain their kinetic energy, and are eventually left at the trap focus with less kinetic energy than before. We experimentally study the effectiveness of barrier-cooling, focusing on how experimental limitations affect the cooling limit. [Preview Abstract] |
Saturday, May 29, 2010 9:00AM - 9:12AM |
W5.00006: Simultaneous Optical Trapping of Lithium and Ytterbium Atoms Vladyslav Ivanov, Alexander Khramov, Anders Hansen, William Dowd, Subhadeep Gupta Simultaneous trapping of different atomic species forms the starting point for experiments probing strong interactions and aspects of superfluidity in mass-imbalanced ultracold mixtures, as well as the synthesis of dipolar molecules through interspecies scattering resonances. Our choice of lithium (Li) and ytterbium (Yb) atoms as the two constituent species is based on several reasons. Both Li and Yb possess stable bosonic and fermionic isotopes which can be independently brought to quantum degeneracy. Li is a one-electron atom and Yb is a two-electron atom, allowing the use of species-selective trapping methods with magnetic fields, magnetic trapping of diatomic LiYb molecules, and a large molecular electric dipole moment for studies of strongly dipolar gases. Ultracold polar LiYb is also a promising candidate for a sensitive electron electric dipole moment (EDM) measurement. We have achieved simultaneous magneto-optical trapping of lithium and ytterbium atoms by loading Zeeman slowed atomic beams from two separate beamlines. We will report on our experimental setup and latest experiments on trapping and cooling of both species in a far off resonance optical trap. [Preview Abstract] |
Saturday, May 29, 2010 9:12AM - 9:24AM |
W5.00007: Narrow linewidth cooling of $^{6}$Li P.M. Duarte, T.A. Corcovilos, J.M. Hitchcock, R.G. Hulet We present progress toward the realization of narrow linewidth laser cooling on the $2S_{1/2}\rightarrow 3P_{3/2}$ transition of $^{6}$Li at 323 nm. Laser cooling on the D2 transition of $^{6}$Li at 671 nm is limited to 140 $\mu$K due to the 5.9 MHz transition linewidth. The 323 nm UV transition has a linewidth of 150 kHz, reducing the Doppler limit of laser cooling to 20 $\mu$K, still above but comparable to the recoil limit of 15 $\mu$K. We expect that implementing a stage of UV laser cooling after our 671 nm magneto-optical trap will enhance the phase-space density of the gas by a factor of 20. This will allow efficient loading to a moderately deep (700 $\mu$K) optical trap/lattice directly after laser cooling without the need of an additional deeper optical trap between the MOT and lattice stages, in contrast with other all-optical $^{6}$Li experiments. [Preview Abstract] |
Saturday, May 29, 2010 9:24AM - 9:36AM |
W5.00008: Toward magnetic trapping of isotopes of hydrogen Robert Clark, S. Travis Bannerman, Isaac Chavez, Adam Libson, Tom Mazur, Mark Raizen Over the past decades, spectroscopy of atomic hydrogen has enabled precision measurements of many fundamental physical quantities. While atomic hydrogen has previously been trapped, its heavier isotopes deuterium and tritium have not. One promising technique for obtaining these 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 deuterium and tritium through the recently discovered technique of single-photon cooling. [Preview Abstract] |
Saturday, May 29, 2010 9:36AM - 9:48AM |
W5.00009: A pulsed Sisyphus scheme for laser cooling of atomic hydrogen Saijun Wu, Roger C. Brown, William D. Phillips, J.V. Porto We discuss a 3-level laser cooling scheme and its application to cooling atomic Hydrogen. In this scheme, ground state atoms are repetitively excited to a meta-stable state that is shifted and quenched by a standing wave laser, and are subsequently cooled by a Sisyphus effect. We demonstrate numerically that this cooling scheme can have a large capture velocity and can have sub-Doppler equilibrium temperatures. The scheme may be particularly useful for cooling of atomic species that require deep-UV lasers for electronic excitations. In particular, we discuss the possibility of cooling magnetically trapped hydrogen atoms from a Kelvin down to 10's of milli-Kelvin temperatures with manageable photo-ionization and spin-flip losses, using high-power 2S-3P laser light (at 656 nm) and pulsed 1S-2S 2-photon excitation (at 243 nm). [Preview Abstract] |
Saturday, May 29, 2010 9:48AM - 10:00AM |
W5.00010: Stable Trap for Neutral Atoms with a Superconducting Disc Tetsuya Mukai A stable magnetic quadrupole trap for neutral atoms on a
superconducting Nb thin-film disc is demonstrated. The
quadrupole field is composed of the magnetic field that is
generated by vortices on the disc introduced by field cooling
of the disc, and a uniform external field perpendicular to the
disc surface. The dynamics and stability of the trap are
studied. The trap is stable when all trapping processes are
performed above the dendritic instability temperature $T_a$.
When the field intensity is changed below this temperature, the
quadrupole field collapses, and the trap disappears. The
initial vortex density decreases even when the external field
is changed at a temperature $T>T_a$. However, the vortex
density is stabilized at an equilibrium density, whereas at
$T |
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