Bulletin of the American Physical Society
39th Annual Meeting of the APS Division of Atomic, Molecular, and Optical Physics
Volume 53, Number 7
Tuesday–Saturday, May 27–31, 2008; State College, Pennsylvania
Session P1: Neutral Atom Entanglement (Co-Sponsored by GQI) |
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Chair: Rene Stock, University of Toronto Room: Nittany Lion Inn Ballroom CDE |
Friday, May 30, 2008 11:00AM - 11:36AM |
P1.00001: Controlled Interaction Between Pairs of Atoms in a Double-Well Optical Lattice Invited Speaker: I will describe recent experiments studying ultra-cold atoms in a dynamic, double-well lattice. Using this lattice, we are able to isolate arrays of atom pairs, and separately control the internal states of the atoms in each pair. By controlling interactions between the atoms we are able to induce a controlled exchange interaction between the two atoms, the essential feature of a quantum SWAP gate. Such a lattice provides a test-bed for ideas in neutral atom quantum computing, and a flexible platform for simulating correlated many-body physics. [Preview Abstract] |
Friday, May 30, 2008 11:36AM - 12:12PM |
P1.00002: Single atoms in optical tweezers for quantum computing Invited Speaker: Our group is interested in neutral atom quantum computing. With this goal in mind, we have recently shown how a single rubidium atom trapped in an optical tweezer can be used to store, manipulate and measure a qubit. I will detail in this talk how we trap and observe a single atom in an optical tweezer created by focusing a far-off resonant laser down to a sub-micron waist. Our qubit is encoded on the $\vert $0$\rangle =\vert $F =1, M=0$\rangle $ and $\vert $1$\rangle =\vert $F =2, M=0$\rangle $ hyperfine sublevels of a rubidium 87 atom. We initialize the qubit by optical pumping. We read the state of the qubit using a state selective measurement limited by the quantum projection noise. We perform single qubit operation by driving a two-photon Raman transition. We have measured the coherence time of our qubit by Ramsey interferometry. After applying a spin-echo sequence, we have found an irreversible dephasing time of about 40 ms. To perform a computation, a feature is the ability to perform a gate between two arbitrary qubits of the register. As a first step, we have demonstrated a scheme where the qubit is transfered between two tweezers with no loss of coherence and no change in the external degrees of freedom of the atom. We have then moved the atom over distances typical of the separation between atoms in an array of dipole traps, and shown that this transport does not affect the coherence of the qubit. Finally, I will present our progress towards entangling two atoms, a key ingredient towards building a two-qubit gate. [Preview Abstract] |
Friday, May 30, 2008 12:12PM - 12:48PM |
P1.00003: Quantum Information Processing with Alkaline-Earth-Like Atoms Invited Speaker: Ultracold alkaline-earth-like atoms offer an attractive platform for quantum information processing. ~Nuclear spins are decoupled from electronic angular momentum in the closed shell 1S0 ground state, thereby providing a robust and isolated degree of freedom for a storing qubit. The 1S-$>$3P intercombinations lines provide the means to optically manipulate qubits in unique ways with very long coherence times. ~We present a variety of protocols that make use of these features. ~Due to the identical particle statistics, nuclear-spin exchange can be used to implement a sqrt-swap entangling quantum logic gate via cold s-wave collisions, even when there is no hyperfine or spin-spin dipolar interactions. ~The ability to independently manipulate nuclear and electronic degrees of freedom can allow us to cool atomic motion without decohering nuclear spin qubits via laser cooling or sympathetic cooling in a BEC reservoir. ~Finally, optical Feshbach resonances on the intercombination line allow for control of~atom coupling strengths at the heart of many protocols in QIP. [Preview Abstract] |
Friday, May 30, 2008 12:48PM - 1:24PM |
P1.00004: Controlling interaction of ultracold atoms in an optical superlattice Invited Speaker: First, I will briefly review the methods to control spin- exchange interaction for ultracold atoms in an optical lattice [1], and the recent experimental techniques to demonstrate the second-order tunneling responsible for the spin exchange interaction with a superlattice [2]. Then, I will discuss the interaction for strongly interacting atoms in a lattice near a wide Feshbach resonance. The strong interaction brings in a number of new features such as multi-band populations and direct neighboring interaction. Under certain circumstances, this complicated system can be described by an effective single- band model (the general Hubbard model) which has particle assisted tunneling for the atoms [3]. The particle assisted tunneling means that the effective atomic tunneling rate from the site i to j depends on whether there is another atom on these two sites. The particle assisted tunneling brings in new feature for quantum many-body physics. I will describe an experimental scheme to test the prediction of the particle assisted tunneling for strongly interacting atoms based on the use of the optical superlattice technique [4]. \newline [1] L.-M. Duan, E. Demler, M. D. Lukin, Controlling Spin Exchange Interactions of Ultracold Atoms in Optical Lattices, Phys. Rev. Lett. 91, 090402 (2003). \newline [2] S. F\"olling, S. Trotzky, P. Cheinet, M. Feld, R. Saers, A. Widera, T. M\"uller, I. Bloch, Direct Observation of Second Order Atom Tunnelling, Nature 448, 1029 (2007). \newline [3] L.-M. Duan, Effective Hamiltonian for fermions in an optical lattice across a Feshbach resonance, cond-mat/0508745, Phys. Rev. Lett. 95, 243202 (2005); L.-M. Duan General Hubbard model for strongly interacting fermions in an optical lattice and its phase detection, arXiv:0706.2161, Europhys. Lett. 81, 20001 (2008). \newline [4] T. Goodman, L.-M. Duan, Test of particle assisted tunneling with strongly interacting atoms in an opticla superlattice, in preparation. [Preview Abstract] |
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