Bulletin of the American Physical Society
2013 Joint Meeting of the APS Division of Atomic, Molecular & Optical Physics and the CAP Division of Atomic, Molecular & Optical Physics, Canada
Volume 58, Number 6
Monday–Friday, June 3–7, 2013; Quebec City, Canada
Session P3: Cooling Methods for Molecules |
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Chair: Phil Gould, University of Connecticut Room: 202 |
Thursday, June 6, 2013 2:00PM - 2:12PM |
P3.00001: Two species Bose-Einstein condensate of $^{23}$Na and $^{87}$Rb Xiaoke Li, Dezhi Xiong, Fudong Wang, Dajun Wang $^{23}$Na and $^{87}$Rb are the first two species to be Bose-Einstein condensed in 1995 and they continue to be two of the most popular atoms for quantum gas researches since. Both ultracold mixtures of these two atoms and ground state NaRb molecules are also of great interest to study. We report on the first realization of the double condensate of these two atoms by exploiting evaporative cooling and sympathetic cooling techniques in a hybrid trap. The two condensates are observed to be immiscible with both atoms prepared in the $|1,-1\rangle$ spin states. This behavior is consistent with the interspecies interaction strength extracted from a cross-species thermalization measurement. Future experiments with this system will also be discussed. [Preview Abstract] |
Thursday, June 6, 2013 2:12PM - 2:24PM |
P3.00002: Double BEC of Rb and Sr: the power of sympathetic narrow-line cooling Benjamin Pasquiou, Alex Bayerle, Simon Stellmer, Slava Tzanova, Rudolf Grimm, Florian Schreck We report on the creation of a rubidium/strontium double BEC. A striking aspect of our method is the efficient cooling of rubidium by strontium atoms, which are laser cooled on a narrow intercombination line. This powerful technique allows us to cool the mixture to 1 microkelvin, reaching a phase-space density of 0.07 for Sr and 0.015 for Rb in an optical trap. Evaporative cooling from such favorable starting conditions leads to simultaneous Bose-Einstein condensation of both species, with 1.5 $\times$ 10$^{5}$ atoms in each cloud. The sympathetic narrow-line cooling could be very helpful to bring other species and mixtures to quantum degeneracy. Double BEC of Rb and Sr is the first step on our path to produce open-shell polar molecules. Contrary to bi-alkali molecules studied so far, alkali/alkaline-earth RbSr molecules will exhibit both an electric and magnetic dipole moment. This additional internal degree of freedom will give us more flexibility to control RbSr molecules, and will be helpful for the simulation of spin dependent lattice models. [Preview Abstract] |
Thursday, June 6, 2013 2:24PM - 2:36PM |
P3.00003: Evaporative cooling of reactive polar molecules confined in a 2D geometry Bihui Zhu, Goulven Qu\'em\'ener, John Bohn, Ana Maria Rey, Murray Holland Recent experimental developments in loading ultracold ${}^{40}$K$^{87}$Rb molecules into quasi-2D traps together with the tunability of the ratio between elastic and inelastic interactions by controlling a DC electric field are opening the door for evaporative cooling of reactive polar molecules. We use Monte Carlo simulations and semianalytic models to study experimental parameter regimes in which evaporative cooling is feasible. Specifically, we investigate how the anisotropic character of dipole-dipole collisions together with the reduced dimensionality affect the efficiency of evaporative cooling. We also investigate anti-evaporation effects induced by chemical reactions that take place when more than one vibrational state is populated along the axial direction. [Preview Abstract] |
Thursday, June 6, 2013 2:36PM - 2:48PM |
P3.00004: A Centrifuge Decelerator: Slowing down Continuous Beams of Polar Molecules by an Inertial Force Sotir Chervenkov, Xing Wu, Josef Bayerl, Andreas Rohlfes, Martin Zeppenfeld, Gerhard Rempe We present the concept of and show compelling experimental results from a novel and versatile decelerator for continuous beams of neutral polar molecules, which employs the centrifugal potential in a rotating frame. A beam of polar molecules is injected at the periphery and electrically guided [1] to the center of the rotating frame along a spiral-shaped electrostatic quadrupole guide. Thus the molecules climb up the centrifugal potential hill and get decelerated as they propagate. In proof-of-principle experiments we demonstrate the deceleration of continuous beams of neutral CF$_3$H, CH$_3$F, and CF$_3$CCH from a liquid-nitrogen cooled effusive source, yielding continuous output intensities exceeding $10^8\,\rm{molecules}\,\rm{mm^{-2}}\,\rm{s^{-1}}$ with velocities below $20\,\rm{m}\,\rm{s^{-1}}$.\\[4pt] [1] S.A. Rangwala et al., Phys. Rev. A {\bf 67}, 043406 (2003) [Preview Abstract] |
Thursday, June 6, 2013 2:48PM - 3:00PM |
P3.00005: A permanent magnet trap for buffer gas cooled atoms and molecules D. Nohlmans, S.M. Skoff, R.J. Hendricks, D.M. Segal, B.E. Sauer, E.A. Hinds, M.R. Tarbutt Cold molecules are set to provide a wealth of new science compared to their atomic counterparts [1]. Here we want to present preliminary results for cooling and trapping atoms/molecules in a permanent magnetic trap. By replacing the conventional buffer gas cell [2] with an arrangement of permanent magnets, we will be able to trap a fraction of the molecules right where they are cooled. For this purpose we have designed a quadrupole trap using NdFeB magnets, which has a trap depth of 0.4 K for molecules with a magnetic moment of 1 $\mu_{\mathrm{B}}$. Cold helium gas is pulsed into the trap region by a solenoid valve and the atoms/molecules are subsequently ablated into this and cooled via elastic collisions, leaving a fraction of them trapped. This new set-up is currently being tested with lithium atoms as they are easier to make. After having optimised the trapping and detection processes, we will use the same trap for YbF molecules. \\[4pt] [1] L.D. Carr, D. DeMille, R.V. Krems and J. Ye, \textit{New J. Phys}. 11, 055049 (2009)\\[0pt] [2] S. M. Skoff, R. J. Hendricks, C. D. J. Sinclair, J. J. Hudson, D. M. Segal, B. E. Sauer, E. A. Hinds and M. R. Tarbutt, \textit{Phys. Rev. A} 83, 023418 (2011) [Preview Abstract] |
Thursday, June 6, 2013 3:00PM - 3:12PM |
P3.00006: Towards Magnetic Trapping of Polar Molecules from a Slow Buffer Gas Beam Hsin-I Lu, Ivan Kozyryev, Boerge Hemmerling, Julia Piskorski, John Doyle General methods for delivering cold, chemically diverse molecules in large quantities could have a profound impact in the areas of quantum simulation, cold controlled chemistry, and particle physics using resonance methods. We report our progress towards loading of a very slow molecular beam into a deep magnetic trap via optical pumping. Employing a two-stage buffer gas cell configuration, we have produced a cold and slow CaF beam with a forward velocity of $v_{f}\sim65$ m/s and a velocity spread of $\delta v_l\sim 40$ m/s. A hexapole magnetic lens is used to focus the molecular beam into a 4 T deep magnetic trap, located at 30 cm from the source. We plan to optically pump the molecules in two steps, achieving magnetic deceleration and irreversible trap loading. Since only a few photon scattering is required during the process, this method could be applicable to a wide range of magnetic molecules, including those lacking closed cycling transitions. Continuous loading to build up the molecular density as well as co-trapping of multiple species are feasible. Cold collisions and sympathetic cooling will be studied based on this work. [Preview Abstract] |
Thursday, June 6, 2013 3:12PM - 3:24PM |
P3.00007: A Magneto-Optical Trap for Diatomic Molecules Mark Yeo, Matthew Hummon, Alejandra Collopy, Benjamin Stuhl, Boerge Hemmerling, Garrett Drayna, Eunmi Chae, Aakash Ravi, Hsin-I Lu, John Doyle, Jun Ye The magneto-optical trap (MOT) has long been the workhorse for atomic physics and is a powerful technique to rapidly produce ultracold, densesamples of atoms. Extending this technique to produce cold, dense samples of a diverse set of molecules will revolutionize the study of strongly interacting quantum systems, precision measurement and physical chemistry. In this work we demonstrate transverse magneto-optical trapping, in 1D and 2D, of a YO molecular beam using a quasi-cycling transition and an oscillating quadrupole magnetic field. We will then report on progress made towards the realization of a 3 dimensional molecular MOT. [Preview Abstract] |
Thursday, June 6, 2013 3:24PM - 3:36PM |
P3.00008: Toward Laser Cooling of CaF Boerge Hemmerling, Garrett Drayna, Eunmi Chae, Aakash Ravi, Hsin-I Lu, Mark Yeo, Matthew T. Hummon, Alejandra Collopy, Benjamin K. Stuhl, Jun Ye, John M. Doyle The prospects of novel physics employing polar cold molecules encompass quantum computing and simulations, controlled ultra-cold chemistry and precision measurements. However, a method liable to bring a general class of chemically diverse molecules to the ultracold regime still needs to be developed. We report on the progress of experiments to laser cool CaF molecules, including the implementation of a magneto-optical trap (MOT). We use a 2-stage buffer-gas cooled beam source to produce a cold and slow beam of particles [1]. In this experiment, we plan to load the trap from this buffer-gas source. As a precursor to working with CaF, we successfully implemented the first buffer-gas loaded MOT of Yb, without the use of a Zeeman slower, but using only a non-chirped slowing laser. The lifetime of the MOT was measured to be $>100$\,ms, with the distance between the source and the MOT $\sim 30$\,cm. We describe a scheme for the laser cooling and magneto-optical confinement of CaF molecules, following an approach similar to those used in the cooling of SrF and YO [2,3].\\[0pt] [1] N.R. Hutzler, et al., Chem. Rev. 112, 4803 (2012). 2. E.F. Shuman, et al., Nature 467, 820 (2010). 3. M.T. Hummon, et al., arXiv:1209.4069 (2012) [Preview Abstract] |
Thursday, June 6, 2013 3:36PM - 3:48PM |
P3.00009: Laser Controlled Rotational Cooling in Na$_2$ Based on Exceptional Points Viatcheslav Kokoouline, Adam Wearne, Roland Lefebvre, Osman Atabek In this study, we describe a computational simulation of the interaction of diatomic molecule with an applied laser field. It is known that for certain laser wavelengths and intensities, the wave functions and eigenenergies of two states become degenerate. Such locations in the laser parameter space are known as ``exceptional points.'' Applying a laser pulse of which encircles one or more exceptional points in the parametric plane of wave length versus intensity, one can bring an ensemble of diatomic molecule into a pre-selected rovibrational state after the laser pulse is over. During this process, a fraction of the molecules dissociate, and those, which remain, are brought to the chosen rovibrational state. Although this scheme can be applied more generally, here we use Na$_2$ as an illustrative example. We examine the locations in the parametric space of exceptional points, which lead to the exchange of rotational states, and how the shape of laser pulse in the parametric plane affects the ``purification'' of the chosen rovibrational state and the dissociation of other states. This work is supported by the National Science Foundation, Grant No PHY-10-68785. [Preview Abstract] |
Thursday, June 6, 2013 3:48PM - 4:00PM |
P3.00010: Rotational Cooling of Trapped SiO$^{+}$ by Optical Pumping David Tabor, Jason Nguyen, Yen-Wei Lin, Fillan Grady, Brian Odom We present results for preparation of trapped molecular ions with a high degree of internal state purity by optical pumping with a broadband pulse-shaped femtosecond laser. The highly diagonal Franck-Condon factors of the dipole-allowed B-X transition in SiO$^{+}$ make optical pumping on the P-branch of this transition favorable for fast stepwise pumping through the tens of rotational levels populated in a room-temperature distribution. By using resonance enhanced multiphoton dissociation (1+1' REMPD) to state-selectively form Si$^{+}$, we probe the internal states of our SiO$^{+}$ sample and determine the degree of rotational cooling. [Preview Abstract] |
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