Bulletin of the American Physical Society
2006 37th Meeting of the Division of Atomic, Molecular and Optical Physics
Tuesday–Saturday, May 16–20, 2006; Knoxville, TN
Session N3: Atoms in Optical Lattices |
Hide Abstracts |
Chair: Sabrina Leslie, University of California, Berkeley Room: Knoxville Convention Center 301D |
Thursday, May 18, 2006 1:30PM - 1:42PM |
N3.00001: A lattice of double wells for manipulating pairs of cold atoms. Jennifer Sebby-Strabley, Marco Anderlini, Ben Brown, Johnny Huckans, Jens Kruse, Patricia Lee, Ian Spielman, Steve Rolston, James Porto, William Phillips We describe the design and implementation of a 2D optical lattice of double wells suitable for isolating and manipulating an array of individual pairs of atoms in an optical lattice. Atoms in the square lattice can be placed in a double well with any of their four nearest neighbors. The properties of the double well (the barrier height and the energy offset of the paired sites) can be dynamically controlled. The topology of the lattice is phase stable against phase noise imparted by vibrational phase noise on mirrors. We demonstrate the dynamic control of the lattice by showing the coherent splitting of atoms from single wells into double wells and observing the resulting double-slit atom diffraction pattern. This lattice can be used to test controlled neutral atom motion among lattice sites and should allow for testing controlled two-qubit gates. [Preview Abstract] |
Thursday, May 18, 2006 1:42PM - 1:54PM |
N3.00002: Experiments with Ultra-cold Atoms in an Optical Lattice with Dynamically Variable Lattice Constant John Huckans, Ian Spielman, Bruno Laburthe Tolra, J.V. Porto, W.D. Phillips We have implemented a one-dimensional optical lattice whose periodicity may be dynamically varied with ultra-cold atoms in-situ. We have measured atom heating rates in the lattice as a function of lattice periodicity ramp velocities and profiles. We superimpose another one-dimensional lattice with fixed periodicity and measure atom diffraction as a function of the ratio of the two competing periodicities. Finally, we report interesting near field atomic diffraction results for extremely large periodicity lattices. [Preview Abstract] |
Thursday, May 18, 2006 1:54PM - 2:06PM |
N3.00003: Probing Localization Physics with a Bose-Einstein Condensate Subject to Optical Random Potential: Interplay of Interaction and Disorder Yong P. Chen, M. Junker, D. Dries, C. Welford, J. Hitchcock, R. G. Hulet The ubiquitous control over physical parameters of a Bose-Einstein condensate (BEC) subject to optical disorder makes this system an exciting playground to address many important issues in localization physics of condensed matter. Examples include Anderson localization, Bose glass, and metal-insulator transition. We have constructed an apparatus that enables us to study an optically trapped $^7$Li BEC in the presence of various optical random potential profiles. Both the interaction and disorder parameters of the system can be tuned. I'll discuss our on-going experiments that focus on the interplay between the correlation lengths of BEC and of the disorder. [Preview Abstract] |
Thursday, May 18, 2006 2:06PM - 2:18PM |
N3.00004: Quantum coherence of Hard-Core-Bosons and Fermions: Extended, Glassy and Mott Phases Ana Maria Rey, Indubala I. Satija , Charles W. Clark Disorder has drastic effects in quantum systems of fermions and bosons. For non-interacting particles it leads to Anderson localization and to a metal-insulator transition. When interactions are present, the effects are even more drastic and the different phases induced by the interplay between disorder and interactions has been a topic of continuous theoretical interest. Cold atoms confined by a periodic lattice offer a unique laboratory to explore disordered systems in a controlled manner. I will discuss the use of Hanbury-Brown-Twiss interferometry (HBTI) to study various quantum phases of hard core bosons (HCBs) and ideal fermions confined in a one-dimensional lattice plus an additional quasi-periodic (QP) potential introduced to add pseudo-random disorder. In particular I will show the QP potential induces for HCBs a cascade of Mott-like band-insulator phases, in addition to the Mott insulator, Bose glass, and superfluid phases . The new phases are heralded by a peak to dip transition in the interferogram. On the other hand I will show that ideal fermions display various features characteristic of incommensurate structures such as devil's staircases and Arnold tongues. Finally, I will discuss why HBTI provides an effective method to distinguish Mott and glassy phases [Preview Abstract] |
Thursday, May 18, 2006 2:18PM - 2:30PM |
N3.00005: Metal-insulator transition revisited for cold atoms in non-Abelian gauge potentials Daniel Dakin, Indubala Satija We investigate an analog to the metal-insulator transition that occurs in two-dimensional electron dynamics in a lattice and a perpendicular magnetic field. This localization transition is controlled by the ratio of the anisotropic coupling strengths. Recent theoretical work has demonstrated the ability to simulate this electronic system with cold atoms in an optical lattice using laser beams, allowing one to exploit the benefits of quantum control to study an otherwise difficult strongly correlated condensed matter problem. With extensions to this work, it is possible to create artificial gauge potentials that transform under non-Abelian gauge groups. We study the localization phase transition in the context of cold atoms in an optical lattice under the influence of non-Abelian gauge potentials. [Preview Abstract] |
Thursday, May 18, 2006 2:30PM - 2:42PM |
N3.00006: Quantum reflection of Bose-Einstein condensates from nano-pillars T.A. Pasquini, M. Saba, Y. Shin, G. Jo, C. Christensen, S. Will, D.E. Pritchard, W. Ketterle We observed quantum reflection of Bose-Einstein condensates from a square array of silicon pillars 50 nm in diameter and spaced at 500 nm at probabilities of up to 67\%. For normal incident velocities of 2.5-26 mm/s observations were in good agreement with theoretical calculations based on single atoms interacting with the Casimir potential of a reduced density surface. At low velocities (0.5-2.5 mm/s), we observe that the reflection probability saturates, remaining near an average 55\% rather than increasing to unity. We provide a simple model that quantitatively predicts the saturation behavior for the reflection of a condensate by including a mean field interactions into the single atom theory. Additionally, we observe coherent excitations of the reflected condensate and incoherent s-wave scattering due to the collision between the incident and reflected condensate. [Preview Abstract] |
Thursday, May 18, 2006 2:42PM - 2:54PM |
N3.00007: Interaction-induced localization of an impurity in a trapped Bose-Einstein condensate Ryan Kalas, D. Blume We study the ground state properties of a trapped Bose condensate with a neutral impurity. By varying the strength of the attractive atom-impurity interactions the degree of localization of the impurity at the trap center can be controlled. As the impurity becomes more strongly localized the peak condensate density, which can be monitored experimentally, grows markedly. For strong enough attraction, the impurity can make the condensate unstable by strongly deforming the atom density in the neighborhood of the impurity. This ``collapse'' can possibly be investigated in bosenova-type experiments. [Preview Abstract] |
Thursday, May 18, 2006 2:54PM - 3:06PM |
N3.00008: Coherent collisional spin-dynamics in an optical lattice Artur Widera, Simon F\"olling, Fabrice Gerbier, Torben M\"uller, Immanuel Bloch Coherent control over the spin degree of freedom in ultracold atomic samples is an important ingredient for many applications in quantum information and solid state simulations. We show that the spin-dependent interaction between two $^{87}$Rb atoms sharing one site of an optical lattice leads to a coherent evolution of the interacting spins. We measure several low- damped coherent oscillations between different spin-states, induced by these on-site interatomic collisions. For most of the cases that we have investigated, these spin-oscillations can be described by a Rabi-type model. Moreover, we are able to control these oscillations by external magnetic fields or by microwave fields using the AC-Zeeman effect analogue of the AC- Stark shift. In particular, we can tune the spin-oscillations into resonance yielding full transfer of spin-population or we can completely suppress them. This allows us to use them as a means of measuring the atom number squeezing as the system is brought from the superfluid into the Mott-insulator regime, similar to cavity QED experiments. [Preview Abstract] |
Thursday, May 18, 2006 3:06PM - 3:18PM |
N3.00009: Bragg spectroscopy of Bose-condensed atoms in an optical lattice Xu Du, Shoupu Wan, Emek Yesilada, Changyun Ryu, Daniel Heinzen We have carried out Bragg spectroscopy of the excitation spectrum of Bose-condensed $^{87}$Rb atoms loaded into a three-dimensional optical lattice. We observe a transition between superfluid and Mott insulating states with increasing lattice height [1]. The superfluid state admits sound waves as excitations. In Bragg spectroscopy, two laser beams with adjustable frequency difference $\omega $, intersecting at an angle $\theta $, create such excitations. In our experiment, we monitor the energy transferred to the atoms as a function of the frequency difference at fixed angle. We find that the resonant peak in the Bragg spectrum of the superfluid moves to lower frequencies with increasing lattice strength, in agreement with calculations [2]. We also find evidence of a gap in the excitation spectrum when the gas is in its Mott insulating state. We acknowledge the support of this work by the R. A. Welch Foundation, The N. S. F., and the D.O.E. Quantum Optics Initiative. [1] Markus Greiner \textit{et al.,} Nature \textbf{415}, 39 (2002). [2] Biao Wu, private communications. [Preview Abstract] |
Thursday, May 18, 2006 3:18PM - 3:30PM |
N3.00010: Direct Observation of Sub-Poissonian Number Statistics in a Degenerate Bose Gas. Chih-Sung Chuu, Florian Schreck, Todd P. Meyrath, Gabriel N. Price, Mark G. Raizen We report the direct observation of Sub-Poissonian number fluctuations for a degenerate Bose gas in an optical trap [1]. Reduction of number fluctuations below the Poissonian limit is observed for average numbers that range from 300 to 12 atoms by a controlled reduction of the confining potential in one dimension. The optical trap composed of five optical sheets is integrated with single atom detection with nearly unit quantum efficiency, enabling a direct and in-situ measurement of atom statistics [2]. Future work includes the generation of arbitrary many-body number states, the study of many-body quantum tunneling, and a statistical study of quantum critical phenomena. [1] C.-S. Chuu, F. Schreck, T. P. Meyrath, J. L. Hanssen, G. N. Price, and M. G. Raizen, ``Direct Observation of Sub-Poissonian Number Statistics in a Degenerate Bose Gas,'' Phys. Rev. Lett. 95, 260403 (2005). [2] T. P. Meyrath, F. Schreck, J. L. Hanssen, C.-S. Chuu, and M. G. Raizen, ``Bose-Einstein Condensate in a Box,'' Phys. Rev. A 71, 041604 (2005). [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700