Bulletin of the American Physical Society
40th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 54, Number 7
Tuesday–Saturday, May 19–23, 2009; Charlottesville, Virginia
Session S4: Laser Trapping and Cooling |
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Chair: Kristian Corwin, Kansas State University Room: Clark Hall 108 |
Friday, May 22, 2009 2:00PM - 2:12PM |
S4.00001: Methods for Non-destructive Temperature Measurements in a Magneto-Optical Trap Frank A. Narducci, Dwight Duncan, Grady R. White, James Lough, Jon P. Davis Certain practical applications for precision measurements by atom interferometers require knowledge of the input atom cloud's temperature from realization to realization. Recent work [1,2] has shown how to measure the temperature of atoms in a magneto-optical trap in a non-destructive, {\em in situ} manner. We discuss an alternate, simpler method for the nondestructive measurement of the temperature of an atom cloud and compare our method with earlier techniques. \\[4pt] [1] T. Brzozowski, M. Brzozowska, J. Zachorowski, M. Zawada, W. Gawlik, {\em PRA}, {\bf 71}, 013401 (2005).\\[0pt] [2] M. Brzozowska, T. Brzozowski J. Zachorowski, W. Gawlik, {\em PRA}, {\bf 72}, 061401(R), (2005). [Preview Abstract] |
Friday, May 22, 2009 2:12PM - 2:24PM |
S4.00002: Influence of Optical Molasses in the Loading of a Shallow Optical Trap Mathew Hamilton, Anthony Gorges, Jacob Roberts We have compared loading $^{85}$Rb atoms into a shallow far-off-resonance trap (FORT) from an optical molasses stage following a magneto-optical trap (MOT) stage with loading from a MOT stage only. Examination of the rate of atoms loaded into the FORT as well as the losses from the FORT during both loading processes over a range of detunings and hyperfine pump powers reveals that losses during both are essentially the same. The load rate however, is different enough that the number of atoms which we can trap is improved by a factor of 2 using an optimized sequence which includes an optical molasses stage compared with optimal loading directly from a MOT. These observations are consistent with disruptions due to the magnetic fields present in the MOT. [Preview Abstract] |
Friday, May 22, 2009 2:24PM - 2:36PM |
S4.00003: Cross Species Suppression of Optical Trap Loading Rate in a Heteronuclear Mixture Anthony Gorges, Mathew Hamilton, Jacob Roberts We report the effects of simultaneously loading $^{85}$Rb and $^ {87}$Rb into a far off resonant trap (FORT) resulting in the disruption of the $^{87}$Rb load rate and number loaded. While many problems arise from cooling a relatively dense cloud of atoms (radiation pressure, Raman transitions, etc.), the large detuning between the transitions of $^{85}$Rb and $^{87}$Rb should act to mitigate many of those effects. We observe, however, significant decrease in the load rate and number of one isotope of Rb into the FORT when the other non-resonant isotope is present. For instance if a $^{85}$Rb MOT is present during an $^{87}$Rb FORT load, the loading rate for $^{87}$Rb is reduced even if $^{85}$Rb itself is not loading into the FORT. Examination of the dynamics behind this load rate reduction reveal that it is neither due to elastic collisions nor light- assisted loss. We theorize the long-range dipole-dipole interactions are responsible for the observed load rate reduction. [Preview Abstract] |
Friday, May 22, 2009 2:36PM - 2:48PM |
S4.00004: Multistage Zeeman deceleration A.W. Wiederkehr, S.D. Hogan, M. Andrist, H. Schmutz, B. Lambilotte, F. Merkt In recent years multistage Zeeman deceleration of open shell atoms and molecules has been developed as a possible method to produce cold ($< 1$~K) samples for applications in precision spectroscopy and studies of cold reactive collisions~[1-7]. This contribution will present the strategy followed at ETH Zurich which relies on (i) the generation of strong magnetic field pulses ($> 2$~T) with rise and fall times of only a few microseconds, (ii) the deceleration and loading of samples into quadrupole magnetic traps, (iii) 3D particle trajectory simulations of the complete deceleration and trapping processes, and (iv) comparison of the simulations with measurements of the velocity and spatial distributions of the decelerated and trapped samples. The four generations of Zeeman deceleration and trapping devices developed in our group will be presented and compared using results obtained with different samples. \\[0pt] [1] N.~Vanhaecke \emph{et al.}, Phys. Rev. A \textbf{75}, 031402(R)(2007).\\[0pt] [2] S.~D.~Hogan \emph{et al.}, Phys. Rev. A \textbf{76}, 023412 (2007).\\[0pt] [3] E.~Narevicius \emph{et al.}, New. J. Phys. \textbf{9}, 358 (2007).\\[0pt] [4] E.~Narevicius \emph{et al.}, Phys. Rev. Lett. \textbf{100}, 093003 (2008).\\[0pt] [5] E.~Narevicius \emph{et al.}, Phys. Rev. A \textbf{77}, 051401(R) (2008).\\[0pt] [6] S.~D.~Hogan \emph{et al.}, J. Phys. B \textbf{41}, 081005 (2008).\\[0pt] [7] S.~D.~Hogan \emph{et al.}, Phys. Rev. Lett. \textbf{101}, 143001 (2008). [Preview Abstract] |
Friday, May 22, 2009 2:48PM - 3:00PM |
S4.00005: Efficient Cooling of Paramagnetic Atoms with Single Photons Travis Bannerman, Gabriel Price, Kirsten Viering, Mark Raizen Complete deceleration of supersonic beams of atoms has recently been demonstrated using pulsed magnetic fields. Any atom with a magnetic moment may be decelerated with this technique, opening the door to magnetically trapped samples of nearly any atom in the periodic table at temperatures in the tens of millikelvins. Further cooling of these atoms is not practical with traditional laser cooling methods or evaporative cooling. We review our cooling technique which only requires the atom to possess a magnetic moment and an accessible electric dipole transition. Nearly complete removal of each atom's kinetic energy is achieved through the scattering of a single photon, in a manner characteristic of Maxwell's demon. We present data with $^{87}$Rb and outline the implementation of ``single-photon cooling'' for hydrogen isotopes. [Preview Abstract] |
Friday, May 22, 2009 3:00PM - 3:12PM |
S4.00006: Progress towards trapping of atomic hydrogen isotopes Isaac Chavez, Adam Libson, Tom Mazur, Julia Majors, Mark Raizen Using a series of pulsed electromagnetic coils (atomic coilgun) we can stop supersonic beams of paramagnetic atoms and molecules. We will employ the coilgun method to stop and trap supersonic beams of hydrogen isotopes. The slowed atoms will be trapped in a quadrupole magnetic trap where single-photon atomic cooling will be applied. Further applications will be discussed. [Preview Abstract] |
Friday, May 22, 2009 3:12PM - 3:24PM |
S4.00007: Guiding and Trapping of Rydberg atoms in a linear magnetic atom guide Cornelius Hempel, Mallory Traxler, Varun Vaidya, Georg Raithel We describe an experimental approach and present results on the dynamics of Rydberg atoms in a high-gradient magnetic guiding and trapping apparatus. The setup consists of two parallel current-carrying wires providing a quadrupole trapping potential with a gradient of 2.7~kG$\cdot \mathrm{cm}^{-1}$ at its center. A Ioffe-Pritchard type trap can be formed by superposition of an inhomogeneous longitudinal bias field. Rubidium Rydberg atoms are excited using the two-photon transition 5S$_{1/2}$ $\rightarrow$ 5P$_{3/2}$ $\rightarrow$ $nL$, where $n$ and $L$ are principal and angular-momentum quantum numbers. An ion-imaging insert allows for time-delayed and spatially resolved detection of the excited atoms and their motion within the trapping potential. The excitation geometry is suitable for coherent, highly efficient population of circular Rydberg levels using adiabatic transfer in crossed magnetic and time-dependent electric fields. Circular-state atoms have long radiative lifetimes and small electric polarizabilities, making them ideal for Rydberg-atom trapping experiments and for studies that require long coherence times. [Preview Abstract] |
Friday, May 22, 2009 3:24PM - 3:36PM |
S4.00008: Light scattering from a dense and ultracold atomic gas Dmitriy Kupriyanov, Igor Sokolov, Mark Havey The quantum optical response of high density ultracold atomic systems is important to a wide range of fundamentally and technically important physical processes. We present here a microscopic analysis of the light scattering on such a system, and compare it with a corresponding description based on macroscopic Maxwell theory. Results are discussed in the context of the spectral resonance structure of the scattering cross section, the time-dependent response under a range of conditions, and evolution of these quantities as the atomic density is varied. For high atomic densities, the microscopic theoretical treatment reveals a distributed and configuration dependent narrow resonance structure. This structure is attributed to microcavity spatial structures associated with the dense and ultracold atomic gas. [Preview Abstract] |
Friday, May 22, 2009 3:36PM - 3:48PM |
S4.00009: A New Technique for Measuring Atomic Recoil Frequency Using Coherence Functions Scott Beattie, Brynle Barrett, Iain Chan, Carson Mok, Itay Yavin, A. Kumarakrishnan We have developed a new technique for measuring the atomic recoil frequency using a single-state echo type atom interferometer that manipulates laser cooled atoms in the ground state. The interferometer relies on momentum state interference due to 2 standing wave pulses that produce density gratings. The interference is modified by applying a 3$^{rd}$ standing wave pulse during the interferometer pulse sequence. As a result, the grating contrast exhibits periodic revivals at the atomic recoil frequency, $\omega _{r}$ as a function of the time at which the 3$^{rd}$ pulse is applied, allowing $\omega _{r}$ to be measured easily and precisely. The contrast is accurately described by a coherence function, which is the Fourier transform of the momentum distribution, produced by the 3$^{rd}$ pulse and by the theory of echo formation. If the 3$^{rd}$ pulse is a traveling wave, loss of grating contrast is observed, an effect also described by a coherence function. The decay of the grating contrast as a function of continuous wave light intensity is used to infer the cross section for photon absorption. Details of this work will be published in PRA Rapid Comm. (2009). [Preview Abstract] |
Friday, May 22, 2009 3:48PM - 4:00PM |
S4.00010: Transient enhancement of the nonlinear atom-photon coupling via recoil-induced resonances Joel Greenberg, Daniel Gauthier We use an optically dense, anisotropic magneto-optical trap to study recoil-induced resonances (RIRs) in the transient, high-gain regime.~ In particular, we find that the finite atomic response time and redistribution of momentum-space population govern the atomic dynamics.~ By simultaneously allowing one to engineer the atomic momentum distribution and exploit gain enhancements due to collective effects, our system is a promising candidate for the realization of few-photon nonlinear optical effects in a traveling-wave geometry for application to quantum information networks. [Preview Abstract] |
Friday, May 22, 2009 4:00PM - 4:12PM |
S4.00011: Towards the creation of Fock states of atoms Hrishikesh Kelkar, Tongcang Li, David Medellin, Kirsten Viering, Mark Raizen Degenerate Bose and Fermi gases have proven to be extremely useful in understanding many quantum phenomenon and quantum phases. However, precise control over the atom number which could enable a clean study of quantum few body systems is still not achieved. Using the method of laser culling of atoms [1] we have already demonstrated sub Poissonian number distribution for $^{87}$Rb atoms [2]. A new setup in $^{23}$Na will improve upon this result by having much higher trap frequencies, optical access and spatially resolved single atom detection, taking us closer to the goal of creating Fock states. [1] A.M. Dudarev, Q. Niu, and M.G. Raizen. Phys. Rev. Lett. \textbf{98}, 063001 (2007). [2] C.-S. Chuu, F. Schreck, T.P. Meyrath, J.L. Hanssen, G.N. Price, and M.G. Raizen. Phys. Rev. Lett. \textbf{59}, 260403 (2005). [Preview Abstract] |
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