Bulletin of the American Physical Society
48th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 62, Number 8
Monday–Friday, June 5–9, 2017; Sacramento, California
Session C9: Laser Cooling |
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Chair: David DeMille, Yale University Room: 315 |
Tuesday, June 6, 2017 2:00PM - 2:12PM |
C9.00001: ABSTRACT WITHDRAWN |
Tuesday, June 6, 2017 2:12PM - 2:24PM |
C9.00002: Novel Cooling Of Ultracold Atoms Using Spatially Selective Optical Pumping Jonathan Gilbert, Jacob Roberts A novel cooling technique for ultracold gases will be presented. This technique has relatively few requirements for particular properties of the ultracold gas and thus should be widely applicable. A detailed description of how the cooling technique works will be presented, along with specific predictions for the cooling of an ultracold gas of~$^{\mathrm{87}}$Rb confined in an optical trap. Recent experimental efforts have focused on optimizing the cooling technique over multiple cycles of cooling. We have observed cooling of the gas by more than 20{\%}. Possibilities for improvement in the technique will be discussed. [Preview Abstract] |
Tuesday, June 6, 2017 2:24PM - 2:36PM |
C9.00003: Narrow Linewidth Laser Cooling via Adiabatic Transfer John Bartolotta, Murray Holland, Matthew Norcia, James Thompson, Julia Cline We simulate and provide a theoretical framework for a new cooling method applicable to particles with narrow-linewidth optical transitions. The particles are adiabatically transferred to lower momentum states upon interaction with counter-propagating laser beams that are repeatedly swept over the transition frequency. A reduced reliance on spontaneous emission (compared to Doppler cooling) allows for larger slowing forces. Cooling via a 7.6 kHz dipole forbidden transition in Strontium-88 is simulated using one-dimensional quantum jump and c-number Langevin equation methods. This ``sweep cooling" mechanism also shows promise for application to systems lacking closed cycling transitions, such as molecules. [Preview Abstract] |
Tuesday, June 6, 2017 2:36PM - 2:48PM |
C9.00004: Raman sideband cooling to high phase-space density Alban Urvoy, Jiazhong Hu, Zachary Vendeiro, Wenlan Chen, Vladan Vuletic Raman sideband cooling is a very fast and reliable way of cooling atoms to sub-Doppler temperatures. \\ However, as virtually all methods of optical cooling, it has so far only reached a maximum phase-space density two orders of magnitude below that required for Bose-Einstein condensation. Here, we present our results on Raman sideband cooling in a 2D optical lattice. We observe only limited losses as the atoms are cooled, partly as a result of using optical pumping light that is far detuned to the red of atomic transition. \\ By combining this efficient cooling and the compression of the atomic ensemble into individual 1D lattices, we are able to reach phase-space densities on the order of unity in tightly confined tubes, each containing several tens of atoms. We discuss the applicability of this method for a fast and efficient all-optical creation of a degenerate quantum gas. [Preview Abstract] |
Tuesday, June 6, 2017 2:48PM - 3:00PM |
C9.00005: Laser cooling by adiabatic transfer Matthew Norcia, Julia Cline, John Bartolotta, Murray Holland, James Thompson We have demonstrated a new method of laser cooling applicable to particles with narrow linewidth optical transitions. This simple and robust cooling mechanism uses a frequency-swept laser to adiabatically transfer atoms between internal and motional states. The role of spontaneous emission is reduced (though is still critical) compared to Doppler cooling. This allows us to achieve greater slowing forces than would be possible with Doppler cooling, and may make this an appealing technique for cooling molecules. In this talk, I will present a demonstration of this technique in a cold strontium system. [Preview Abstract] |
Tuesday, June 6, 2017 3:00PM - 3:12PM |
C9.00006: Two Dimensional Grating Magneto Optical Trap in $^{\mathrm{87}}$Rb Eric Imhof, Bethany Kroese, Matthew Squires We demonstrate an enhanced two dimensional grating magneto optical trap with a single input beam and a planar diffraction grating. This configuration allows for an increase in experimental access when compared with a traditional two beam 2D MOT. We find a flux \textgreater 4x10$^{\mathrm{8\thinspace }}$rubidium atoms/s at a mean velocity of 18 m/s. The velocity distribution has a 3 m/s standard deviation. We use the atomic beam to load a three dimensional grating MOT with 2x10$^{\mathrm{8\thinspace }}$atoms. Methods to improve flux output will be discussed. [Preview Abstract] |
Tuesday, June 6, 2017 3:12PM - 3:24PM |
C9.00007: Dual-species MOT for fermionic dysprosium and potassium atoms Vincent Corre, Cornelis Ravensbergen, Slava Tzanova, Elisa Soave, Marian Kreyer, Alexander Werlberger, Emil Kirilov, Rudolf Grimm We report on the first realization of a dual-species magneto-optical trap that combines strongly magnetic lanthanide atoms (dysprosium) with alkali atoms (potassium). Advanced cooling techniques (gray molasses and narrow-line cooling) give us favorable starting conditions for evaporative cooling in an optical dipole trap which, by combining universal dipolar scattering and sympathetic cooling, should allow us to bring polarized samples of both species into the degenerate regime. With naturally abundant fermionic and bosonic isotopes of both dysprosium and potassium, this system provides a versatile platform to study degenerate mixtures. We are particularly interested in Fermi-Fermi mixtures, in which the mass imbalance is expected to give rise to novel pairing mechanisms and exotic quantum phases. [Preview Abstract] |
Tuesday, June 6, 2017 3:24PM - 3:36PM |
C9.00008: Using a directional analog to the Hanle effect to Characterize fields in a magneto-optical trap Jarom Jackson, Dallin Durfee The Hanle effect describes a depolarization of scattered light due to the rotation of atoms in a magnetic field. We will discuss a directional analog to the Hanle effect, in which field-induced rotation changes the spatial emission pattern of the scattered light. We use this effect to measure the spatially dependent magnetic field of a magneto-optical trap (MOT) in situ. The method is well suited for this task, because little to no setup or additional equipment is needed beyond what is typically present in an experiment using a MOT, and the magnitude of the fields in a MOT are naturally in the most sensitive range of this method. [Preview Abstract] |
Tuesday, June 6, 2017 3:36PM - 3:48PM |
C9.00009: High Fidelity Preparation of a Single Atom in Its 2D Center of Mass Ground State Pimonpan Sompet, Yin Hsien Fung, Eyal Schwartz, Matthew D. J. Hunter, Jindaratsamee Phrompao, Mikkel F. Andersen Complete control over quantum states of individual atoms is important for the study of the microscopic world. Here, we present a push button method for high fidelity preparation of a single $^{85}$Rb atom in the vibrational ground state of tightly focused optical tweezers. The method combines near-deterministic preparation of a single atom with magnetically-insensitive Raman sideband cooling. We achieve 2D cooling in the radial plane with a ground state population of 0.85, which provides a fidelity of $\sim$0.7 for the entire procedure (loading and cooling). The Raman beams couple two sublevels ($|F=3,m=0\rangle$ and $|F=2,m=0\rangle$) that are indifferent to magnetic noise to first order. This leads to long atomic coherence times, and allows us to implement the cooling in an environment where magnetic field fluctuations prohibit previously demonstrated variations. Additionally, we implement the trapping and manipulation of two atoms confined in separate dynamically reconfigurable optical tweezers, to study few-body dynamics. [Preview Abstract] |
Tuesday, June 6, 2017 3:48PM - 4:00PM |
C9.00010: Shot-noise dominant regime of a nanoparticle in a laser beam Changchun Zhong, Francis Robicheaux The technique of laser levitation of nanoparticles has become increasingly promising in the study of cooling and controlling mesoscopic quantum systems. Unlike a mechanical system, the levitated nanoparticle is less exposed to thermalization and decoherence due to the absence of direct contact with a thermal environment. In ultrahigh vacuum, the dominant source of decoherence comes from the unavoidable photon recoil from the optical trap which sets an ultimate bound for the control of levitated systems. In this paper, we study the shot noise heating and the parametric feedback cooling of an optically trapped anisotropic nanoparticle in the laser shot noise dominant regime. The rotational trapping frequency and shot noise heating rate have a dependence on the shape of the trapped particle. For an ellipsoidal particle, the ratio of the axis lengths and the overall size controls the shot noise heating rate relative to the rotational frequency. For a near spherical nanoparticle, the effective heating rate for the rotational degrees of freedom is smaller than that for translation suggesting that the librational ground state may be easier to achieve than the vibrational ground state. [Preview Abstract] |
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