Bulletin of the American Physical Society
40th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 54, Number 7
Tuesday–Saturday, May 19–23, 2009; Charlottesville, Virginia
Session R6: Focus Session: Interactions Between Individual Atoms |
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Chair: Thad Walker, University of Wisconsin Room: Minor Hall 209 |
Friday, May 22, 2009 10:30AM - 11:00AM |
R6.00001: Towards entanglement of two individual atoms using the Rydberg blockade Invited Speaker: The Rydberg blockade is of great interest for many quantum information processing schemes, since it provides a way to deterministically entangle two or more atoms and to drive fast quantum gates [1]. Recently, experimental efforts into this direction succeeded in the first observation of the Rydberg blockade between two $^{87}$Rb atoms individually trapped in two neighboring dipole traps [2,3]. Furthermore, in the two atom system the Rabi frequency for oscillations between the ground state $|gg\rangle$ and \emph{one} atom in the Rydberg state is enhanced by $\sqrt 2$ with respect to the Rabi frequency for a single atom [3]. This indicates the production of an entangled state $(|gr\rangle+ e^{i\textbf{k}\Delta \textbf{r}}|rg\rangle)/\sqrt 2$, where $\textbf{k}$ is related to the wave vector of the exciting lasers and $\Delta \textbf{r}$ is the distance between the atoms. The variation of the interatomic distance from shot-to-shot leads to a random phase in the produced entangled state. However, when the Rydberg state is mapped onto another ground state $|g'\rangle$ before the atoms move, this random phase cancels. The resulting entangled state $(|gg'\rangle+ |g'g\rangle)/\sqrt 2$ could then be tested in a Bell measurement or a state tomography. Rotations of the measurement basis are done with a pair of Raman lasers coupling $|g\rangle$ and $|g'\rangle$. The atomic state is read out observing the fluorescence of the remaining atoms after ejecting atoms in state $|g\rangle$ from the trap. The current status of the experiment will be reported.\\[4pt] [1] D.~Jaksch et al., \emph{Phys. Rev. Lett.} \textbf{85}, 2208 (2000). M.D.~Lukin et al., \emph{Phys. Rev. Lett.} \textbf{87}, 037901 (2001).\\[0pt] [2] E.~Urban et al., \emph{Nature Phys.} (2009)(accepted, see also \emph{arxiv:0805.0758}).\\[0pt] [3] A.~Ga\"etan et al., \emph{Nature Phys.} (2009) (accepted, see also \emph{arxiv:0810.2960}). [Preview Abstract] |
Friday, May 22, 2009 11:00AM - 11:30AM |
R6.00002: Observation of long range Rydberg blockade Invited Speaker: Interactions between Rydberg states of neutral atoms are a promising approach for fast and long range quantum gates. We demonstrate that a single Rydberg excited Rb atom blocks excitation of a second atom located more than $10~\mu\rm m$ away. The observed probability of double excitation of $< 20~\%$ is consistent with a theoretical model of the Rydberg interaction. Progress towards using blockade to demonstrate a CNOT gate as well as ideas for efficient creation of multiqubit entanglement will be presented. [Preview Abstract] |
Friday, May 22, 2009 11:30AM - 11:42AM |
R6.00003: Entangled Mechanical Oscillators John D. Jost, J.P. Home, J.M. Amini, D. Hanneke, R. Ozeri*, C. Langer**, J.J. Bollinger, D. Leibfried, D.J. Wineland Quantum entanglement has been the subject of considerable research, in part due to its non-intuitive nature and ubiquitous presence in quantum information processing. For this reason, it is of interest to study entanglement in a variety of systems. We demonstrate deterministic entanglement in a system pervasive in nature: mechanical oscillators. Here, the mechanical oscillators are composed of the vibrations of two Be$^{+}$- Mg$^{+}$ ion pairs held in spatially separate locations. We also demonstrate the entanglement of the internal states of a Be$^{+ }$ ion with a distant mechanical oscillator. The techniques demonstrated in this experiment are likely to form core components of large-scale trapped-ion quantum information processing. * Weizmann Institute of Science, Israel ** Lockheed Martin, Denver, CO [Preview Abstract] |
Friday, May 22, 2009 11:42AM - 11:54AM |
R6.00004: Ultrafast Manipulation of Trapped Ion Qubits Wes Campbell, Qudsia Quraishi, Jonathan Mizrahi, Chris Monroe Ultrashort light pulses are an attractive tool for trapped ion quantum information processing. High pulse intensity permits far-detuned ($>$10 nm) operation, where decoherence from differential AC Stark shifts and spontaneous emission is suppressed. Short pulse duration allows interaction times shorter than a trap oscillation, circumventing the need for cooling to the Lamb-Dicke limit. We describe an experiment with trapped $^{171}$Yb$^+$ using a vanadate laser ($\sim$10 ps pulses at 355 nm). Since the single pulse bandwidth exceeds the $S_{1/2}$ hyperfine splitting, coherent Raman transitions between qubit states should be possible. This is in contrast to our previous work [1] with near-resonant pulses that coherently transfer population to the P-state. It should also be possible to use a series of multiple pulses to impart spin-dependent forces. By controlling the pulse timing and phase we could then entangle multiple ions in a temperature insensitive manner [2,3]. [1] Madsen \textit{et al.}, PRL \textbf{97}, 040505 (2006). [2] Garc\'{i}a-Ripoll \textit{et al.}, PRL \textbf{91}, 157901 (2003). [3] Duan, PRL \textbf{93}, 100502 (2004). [Preview Abstract] |
Friday, May 22, 2009 11:54AM - 12:06PM |
R6.00005: Optical lattice-based addressing and control of long-lived neutral-atom qubits Nathan Lundblad, Ian Spielman, William Phillips, Trey Porto Quantum computational platforms are driven by competing needs: the isolation of the quantum system from the environment to prevent decoherence, and the ability to control the system with external fields. For example, neutral-atom optical-lattice architectures provide environmental isolation through the use of ``clock" states that are robust against changing external fields, yet those same external fields are inherently useful for qubit addressing. Here we demonstrate a technique to address a spatially dense field-insensitive qubit register. A subwavelength-scale effective magnetic-field gradient permits the addressing of selected elements of the qubit register, leaving unmarked qubits unaffected, with little crosstalk or leakage. We demonstrate this technique with rubidium atoms, and show that we can robustly perform single-qubit rotations on qubits located at selected lattice sites. [Preview Abstract] |
Friday, May 22, 2009 12:06PM - 12:18PM |
R6.00006: Dual Degeneracy of Lithium and Cesium Atoms for Scalable Quantum Information Processing Kathy-Anne Soderberg, Arjun Sharma, Kara Lamb, Peter Scherpelz, Andreas Klinger, Skyler Degenkolb, Nathan Gemelke, Cheng Chin We describe first steps in an experiment aimed at scalable quantum information processing with quantum degenerate gases of two atomic species. We discuss simultaneous evaporation of fermionic $^{6}$Li and bosonic $^{133}$Cs atoms. Both atomic species are cooled and trapped in independent magento-optical traps and subsequently transferred to a single dipole trap for evaporative cooling. Cooling the $^{6}$Li atoms into a degenerate band-insulator will allow uniform loading into the optical lattice of one atom/site. These atoms will act as quantum bits (qubits) to store quantum information. A second lattice will confine $^{133}$Cs messenger atoms that will have a low filling ratio of $\sim $1 atom per 100 sites. By translating one lattice relative to the other, the $^{133}$Cs messengers can be transported to any $^{6}$Li qubit for entangling operations. Initial experiments study the interspecies collision properties, serving to guide strategies to implement collision-based entangling operations. [Preview Abstract] |
Friday, May 22, 2009 12:18PM - 12:30PM |
R6.00007: Quantum information processing and quantum simulations with alkaline-earth atoms in an optical lattice Alexey Gorshkov, Eugene Demler, Mikhail Lukin, Andrew Daley, Peter Zoller, Martin Boyd, Jun Ye, Michael Hermele, Victor Gurarie, Ana Maria Rey We describe a method for quantum information processing and quantum simulation with alkaline-earth atoms in an optical lattice. First, we propose and analyze a novel approach to quantum information processing, in which multiple qubits can be encoded and manipulated using electronic and nuclear degrees of freedom associated with individual alkaline-earth atoms trapped in an optical lattice. We discuss potential applications of this approach to fault-tolerant quantum computation and precision measurements. In addition, we propose to use alkaline-earth atoms in optical lattices for quantum simulation of models that are beyond the generic Hubbard model and that rely on the interplay between spin and orbital degrees of freedom. In addition to being interesting and rich in their own right, such models may allow generating fundamental insights into the physics of solid-state systems such as transition metal oxides and heavy fermion materials, which exhibit numerous exotic properties including high temperature superconductivity and spin liquid phases. [Preview Abstract] |
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