Bulletin of the American Physical Society
41st Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 55, Number 5
Tuesday–Saturday, May 25–29, 2010; Houston, Texas
Session C1: DAMOP Thesis Prize Session |
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Chair: Elizabeth McCormack, Bryn Mawr College Room: Imperial East |
Wednesday, May 26, 2010 2:00PM - 2:30PM |
C1.00001: A Quantum Gas of Polar Molecules Invited Speaker: Kang-Kuen Ni I will present our experimental realization of a near quantum degenerate gas of absolute ground-state polar molecules. This result represents more than 10 orders of magnitude improvement in phase-space density (PSD) compared to previous results for polar molecules and is only a factor of 15 in PSD away from quantum degeneracy. I will also present initial ultracold collisional studies in our KRb molecule system. Our high phase-space-density gas of polar molecules is created using two coherent steps. First, atoms in an ultracold gas mixture are converted into extremely weakly bound molecules near a Fano-Feshbach resonance. Second, the weakly bound molecules are transferred to the ro-vibronic ground state using a coherent two-photon Raman technique with an efficiency as high as 90\%. We confirmed that these ground-state molecules are polar with a spectroscopic measurement of their permanent electric dipole moment. Additionally, we demonstrate manipulation of the molecular hyperfine state, where we can produce ultracold polar molecules all in a \textit{single} internal quantum state, and in particular, in their \textit{lowest} energy state. With this gas of molecules, we have studied ultracold collisions, including ultracold chemical reactions and collisions controlled by electric dipole-dipole interactions. \\[4pt] This work was performed at the University of Colorado, Boulder under the direction of Dr. Deborah Jin. [Preview Abstract] |
Wednesday, May 26, 2010 2:30PM - 3:00PM |
C1.00002: Pairing and Superfluidity in Strongly Interacting Fermi Gases Invited Speaker: Christian Schunck Ultracold Fermi Gases are ideal model systems to study strongly interacting fermions. Of particular interest is the crossover regime between two limiting cases of fermionic superfluidity, Bose-Einstein condensation of diatomic molecules and BCS superfluidity of pairs bound by many-body interactions. I will describe experiments investigating the interplay of fermionic pairing and superfluidity in this regime with an ultracold gas of fermionic 6Li atoms. By varying the spin populations and temperature in a two component mixture we study the homogeneous phase diagram of the gas at unitarity, where the only relevant energy scale is the Fermi energy. The phase diagram shows first and second order phase transitions merging at a tricritical point. A zero temperature phase transition from a superfluid to a mixed normal state is observed at a critical spin polarization known as the Chandrasekhar-Clogston (CC) limit. Next pairing correlations are studied with radio-frequency (rf) spectroscopy. Strong correlations are found above the critical temperature but also at spin polarizations above the CC limit. Limitations due to final state interactions are overcome by creating new superfluid spin mixtures. The rf dissociation spectra then allow us to determine the spectroscopic pair size. The pairs are the smallest found in fermionic superfluids, highlighting the importance of small fermion pairs for superfluidity at high critical temperatures. Finally, by observing a peak due to thermally excited quasiparticles, the pairing gap is directly determined from the rf spectra. [Preview Abstract] |
Wednesday, May 26, 2010 3:00PM - 3:30PM |
C1.00003: Quantum Information Processing with Ions and Photons Invited Speaker: Steven Olmschenk Quantum information research is driven by the prospect of using the features of quantum physics to tackle otherwise intractable computational problems. Systems of trapped atomic ions have proven to be one of the most promising candidates for the realization of quantum computation due to their long trapping times, excellent coherence properties, and exquisite control of the internal atomic states. Integrating ions (quantum memory) with photons (distance link) offers a unique path to large-scale quantum computation and long-distance quantum communication. I present the implementation of a heralded photon-mediated quantum gate between remote ions, and the employment this gate to perform a teleportation protocol between two ions separated by a distance of about one meter. A quantum bit stored in the hyperfine levels of a single ytterbium ion (Yb${}^{+}$) is teleported to a second Yb${}^{+}$ atom with an average fidelity of 90\% over a replete set of states. The method demonstrated here avoids many of the issues associated with previously demonstrated motional gates, while presenting a new set of challenges and possibilities for integration to larger systems. [Preview Abstract] |
Wednesday, May 26, 2010 3:30PM - 4:00PM |
C1.00004: Overcoming the grand challenges in Quantum Simulations Invited Speaker: Qi Zhou The highly ambitious goal of the ``Quantum Simulation'' program is to simulate the behavior of strongly correlated solid-state systems using cold atoms in optical lattices. It promises to provide insight into a range of long-standing problems in many-body physics. There are, however, significant challenges which need to be overcome in order for these efforts to succeed. The first challenge is that the required temperatures for studying strongly correlated physics in optical lattices are far below those achievable in laboratories today. The second problem concerns the fact that many important thermodynamic qualities, which distribute non-uniformly in the confining trap, are inaccessible by standard imaging methods. In this talk, I will discuss ways to solve these grand challenges. First, I will present schemes which allow for strongly correlated regimes of atoms in optical lattices to be reached. These schemes are based on transferring the entropy out of the region of interest. Examples will be given to demonstrate that these schemes can reach temperature regions down to a few tens of pico-Kelvin. Secondly, I will discuss algorithms to map out the phase diagrams of quantum models and deduce the thermodynamic properties of homogeneous systems, such as the superfluid density and entropy density, which have eluded cold atom experiments for years. Using only the density profile of trapped atoms as input, these algorithms can fulfill the lofty goal of quantum simulation. [Preview Abstract] |
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