Bulletin of the American Physical Society
47th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 61, Number 8
Monday–Friday, May 23–27, 2016; Providence, Rhode Island
Session T5: New Techniques for Laser Cooling and Trapping |
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Chair: Hal Metcalf, Stonybrook University Room: 551AB |
Friday, May 27, 2016 8:00AM - 8:12AM |
T5.00001: Manipulation of Ultracold Atoms using Double-Loop Microtraps William van Wijngaarden, Bin Jian, Andrei Mouraviev Ultracold atoms created using microtraps are being used in an increasing number of diverse applications. This talk discusses exciting work demonstrating a double-loop microtrap which consists of two concentric circular wire loops carrying oppositely oriented currents. This generates a magnetic field configuration that traps a magnetic dipole in three dimensions. The position of the trapped atoms relative to the atom chip surface containing the microwire loops, can be precisely controlled by applying different currents in the two lops or alternatively using a so called bias magnetic field oriented perpendicular to the chip surface. An important advantage of the double-loop microtrap is that it can be daisy chained in series to create a one or two dimensional microtrap array. Future possibilities are presented as to how atoms can be transferred between adjacent microtraps as well as the use of an additional micro sized Ioffe coil to create a trap having a nonzero magnetic field minimum to reduce atom loss by suppressing Majorana transitions. [Preview Abstract] |
Friday, May 27, 2016 8:12AM - 8:24AM |
T5.00002: Direct frequency comb two-photon laser cooling and trapping Andrew Jayich, Xueping Long, Wesley C. Campbell Generating and manipulating high energy photons for spectroscopy on electric dipole transitions of atoms and molecules with deeply bound valence electrons is difficult. Further, laser cooling of such species is even more challenging for lack of laser power. A possible solution is to drive two-photon transitions [1]. This may alleviate the photon energy problem and open the door to cold, trapped samples of highly desirable species with tightly bound electrons. We perform a proof of principle experiment with rubidium by driving a two-photon transition with an optical frequency comb. We perform optical cooling and extend this technique to trapping, where we are able to make a magneto-optical trap in one dimension. This work is supported by the National Science Foundation CAREER program.\\ \\[1] D. Kielpinski, Phys. Rev. A 73, 063407 (2006) [Preview Abstract] |
Friday, May 27, 2016 8:24AM - 8:36AM |
T5.00003: Construction of a single atom trap for quantum information protocols Margaret E. Shea, Paul M. Baker, Daniel J. Gauthier The field of quantum information science addresses outstanding problems such as achieving fundamentally secure communication and solving computationally hard problems. Great progress has been made in the field, particularly using photons coupled to ions and super conducting qubits. Neutral atoms are also interesting for these applications and though the technology for control of neutrals lags behind that of trapped ions, they offer some key advantages: primarily coupling to optical frequencies closer to the telecom band than trapped ions or superconducting qubits. Here we report progress on constructing a single atom trap for \textsuperscript{87}Rb. This system is a promising platform for studying the technical problems facing neutral atom quantum computing. For example, most protocols destroy the trap when reading out the neutral atom’s state; we will investigate an alternative non-destructive state detection scheme. We detail the experimental systems involved and the challenges addressed in trapping a single atom. All of our hardware components are off the shelf and relatively inexpensive. Unlike many other systems, we place a high numerical aperture lens inside our vacuum system to increase photon collection efficiency. [Preview Abstract] |
Friday, May 27, 2016 8:36AM - 8:48AM |
T5.00004: Towards high phase space density of alkali atoms by simple optical cooling Jiazhong Hu, Zachary Vendeiro, Wenlan Chen, Vladan Vuletic We demonstrate a simple optical cooling method, which can cool down the temperature of rubidium 87 to the ground state of the vibrational levels. We only use one far-detuned laser performing both cooling and optical repumping. By tuning the laser frequency, we verify the dependence of the two-body collision loss versus the laser detuning. Combining with the retrap of the atoms in the optical dipole trap, we can make the phase space density approaching to unity. [Preview Abstract] |
Friday, May 27, 2016 8:48AM - 9:00AM |
T5.00005: Zeeman-Sisyphus Deceleration of Molecular Beams Noah Fitch, Mike Tarbutt Ultracold molecules are useful for testing fundamental physics and studying strongly-interacting quantum systems. One production method is via direct laser cooling in a magneto-optical trap (MOT). In this endeavor, one major challenge is to produce molecules below the MOT capture velocity. Established molecular beam deceleration techniques are poorly suited because they decelerate only a small fraction of a typical molecular pulse. Direct laser cooling is a natural choice, but is also problematic due to transverse heating and the associated molecule loss. I will present a new technique that we are developing, which we call Zeeman-Sisyphus deceleration and which shows great promise for preparing molecular beams for MOT loading. This technique decelerates molecules using a linear array of permanent magnets, along with lasers that periodically optically pump molecules between weak and strong-field seeking quantum states. Being time-independent, this method is well-suited for temporally extended molecular beams. Simultaneous deceleration and transverse guiding makes this approach attractive as an alternative to direct laser cooling. I will present our development of the Zeeman-Sisyphus decelerator and its application to a molecular MOT of CaF and an ultracold fountain of YbF. [Preview Abstract] |
Friday, May 27, 2016 9:00AM - 9:12AM |
T5.00006: Experimental realization of real-time feedback-control of single-atom arrays Hyosub Kim, Woojun Lee, Jaewook Ahn Deterministic loading of neutral atoms on particular locations has remained a challenging problem. Here we show, in a proof-of-principle experimental demonstration, that such deterministic loading can be achieved by rearrangement of atoms. In the experiment, cold rubidium atom were trapped by optical tweezers, which are the hologram images made by a liquid-crystal spatial light modulator (LC-SLM). After the initial occupancy was identified, the hologram was actively controlled to rearrange the captured atoms on to unfilled sites. For this, we developed a new flicker-free hologram algorithm that enables holographic atom translation. Our demonstration show that up to N=9 atoms were simultaneously moved in the 2D plane with the movable degrees of freedom of 2N=18 and the fidelity of 99\% for single-atom 5-$\mu$m translation. It is hoped that our in situ atom rearrangement becomes useful in scaling quantum computers. [Preview Abstract] |
Friday, May 27, 2016 9:12AM - 9:24AM |
T5.00007: Moving Single Atoms Dustin Stuart Single neutral atoms are promising candidates for qubits, the fundamental unit of quantum information. We have built a set of optical tweezers for trapping and moving single Rubidium atoms. The tweezers are based on a far off-resonant dipole trapping laser focussed to a 1 $\mu$m spot with a single aspheric lens. We use a digital micromirror device (DMD) to generate dynamic holograms of the desired arrangement of traps. The DMD has a frame rate of 20 kHz which, when combined with fast algorithms\footnote{D. Stuart et. al., \emph{Fast algorithms for generating binary holograms}, http://arxiv.org/abs/1409.1841}, allows for rapid reconfiguration of the traps. We demonstrate trapping of up to 20 atoms in arbitrary arrangements, and the transport of a single-atom over a distance of 14 $\mu$m with continuous laser cooling, and 5 $\mu$m without. In the meantime, we are developing high-finesse fibre-tip cavities, which we plan to use to couple pairs of single atoms to form a quantum network. [Preview Abstract] |
Friday, May 27, 2016 9:24AM - 9:36AM |
T5.00008: Theoretical model for Sub-Doppler Cooling with EIT System Peiru He, Phoebe Tengdin, Dana Anderson, Ana Maria Rey, Murray Holland We propose a of sub-Doppler cooling mechanism that takes advantage of the unique spectral features and extreme dispersion generated by the so-called Electromagnetically Induced Transparency (EIT) effect, a destructive quantum interference phenomenon experienced by atoms with Lambda-shaped energy levels when illuminated by two light fields with appropriate frequencies. By detuning the probe lasers slightly from the ``dark resonance'', we observe that atoms can be significantly cooled down by the strong viscous force within the transparency window, while being just slightly heated by the diffusion caused by the small absorption near resonance. In contrast to polarization gradient cooling[1] or EIT sideband cooling [2], no external magnetic field or external confining potential are required. Using a semi-classical method, analytical expressions, and numerical simulations, we demonstrate that the proposed EIT cooling method can lead to temperatures well below the Doppler limit. This work is supported by NSF and NIST. [1] JOSA B6.11 (1989): 2023-2045 [2] Physical review letters 85.21 (2000): 4458. [Preview Abstract] |
Friday, May 27, 2016 9:36AM - 9:48AM |
T5.00009: Sisyphus cooling of Trapped Ions as a Route to Experiments in the Quantum Regime Paul C Haljan, Sara Ejtemaee In a linear rf Paul trap, relaxing the transverse confinement can lead laser-cooled trapped ions to undergo a symmetry–breaking structural transition from a linear to a 2-D zigzag configuration. We are interested in exploring the dynamics near the linear-zigzag transition at ultralow temperatures, corresponding to a few quanta or less of thermal energy in the vibrations of the trapped ion crystal. In weaker traps, as in our case, the Lamb-Dicke limit is not strongly fulfilled through Doppler cooling, and Raman sideband cooling of the vibrational modes starting from Doppler temperatures becomes challenging. To resolve this, we have implemented 3-D Sisyphus cooling based on a polarization gradient field as an intermediate step to achieving near ground-state cooling of trapped Ytterbium ions. We have compared the performance of the polarization-gradient cooling of a single trapped ion to simulations, and have extended the technique to cool crystals of a few ions. We find Sisyphus cooling, which has so far not been widely used with trapped ions, to be a simple, robust technique that simultaneously cools all of the vibrational modes to well below the Doppler limit, and paves the way towards our experiments in the quantum regime. [Preview Abstract] |
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