Southwest Quantum Information and Technology

Eleventh Annual Meeting, February 19-22, 2009
Seattle, Washington

Full Program | Thursday | Friday | Saturday | Sunday

SESSION 6: Ion Trap QI
Session Chair:
8:30-9:15	Luming Duan, University of Michigan (invited)
	Large Scale Quantum Computation in a Linear Ion Trap
	Abstract. Among the approaches to quantum computation, the trapped ion system remains as one of the leading candidates. The linear Paul trap provides the most convenient architecture for quantum gate operations over a few ions, and the basic requirements for quantum computation have been demonstrated in this setup. However, scaling up this system to a large number of qubits so far remains a formidable challenge because of several obstacles, including the instability of the linear structure and the difficulties of the sideband cooling and addressing for a large ion array. The recent approach to scalable ion trap computation thus has to use a more complicated architecture where the ions are shuttled over different trapping regions. Here, we propose a way to implement large-scale quantum computation in a linear trap by overcoming all the theoretical obstacles. Through excitation of the transverse photon modes in an anharmonic trap, we show that high-fidelity quantum gates can be achieved on ions in a large linear architecture under the Doppler temperature without the requirement of sideband resolving.
9:15-10:45	John Jost, National Institute of Standards and Technology, Boulder
	Ion Motional Entanglement and Quantum Information Experiments at NIST*
	Abstract. I will summarize current trapped-ion quantum information processing (QIP) experiments at NIST. Quantum entanglement has been the subject of considerable research, in part due to its non intuitive nature and ubiquitous presence in QIP. 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 in spatially separate locations. The techniques demonstrated in this experiment are likely to form core components of large-scale trapped-ion QIP. Other work at NIST includes characterization of ion transport dynamics in a trap array that includes a 2-D junction, recent developments in micro-fabricated surface traps, and studies of dynamic decoupling. * supported by IARPA and the NIST Quantum Information Program
10:15-11:00	Christopher Monroe, JQI and University of Maryland (invited)
	Ion Trap Photonic Quantum Networks
	Abstract. The local manipulation and entanglement of nearby atomic ion qubits through their Coulomb interaction is now established as one of the most reliable ways to build entangled states. Trapped ions can also be coupled through a photonic channel, allowing for various remote probabilistic ion-ion entanglement protocols. Recent experiments have shown entanglement, a Bell inequality violation, teleportation, and operation of a two-qubit quantum gate between two ions separated by 1 meter. Despite the probabilistic nature of this ion/photon network, it can be efficiently scaled to much larger numbers of ions for distributed large-scale quantum computing and long-distance quantum communication, especially when accompanied by local Coulomb-mediated deterministic quantum gates. Future work will couple photons emitted from trapped ions into optical cavities, and perhaps interface trapped ion qubits with other optically-active qubits such as quantum dots.
11:00-11:30	Matt Dietrich, University of Washington
	Preparation and detection of a 137Ba+ hyperfine qubit
	Abstract. We report the initialization and state detection of 137Ba+ hyperfine qubits. We load 137Ba+ into a linear Paul trap by direct photoionization with a Xe discharge lamp. The qubit is initialized by optically pumping into the magnetic field insensitive hyperfine ground state (F=2 m_f=0). State selective shelving to the metastable D5/2 state is accomplished by adiabatic rapid passage using a 1762 nm fiber laser stabilized to a high-finesse cavity, a process which is used for high efficiency state detection. Single qubit rotations are accomplished by RF pulses at the hyperfine splitting (8.037 GHz). Rabi flops excited by individual ultrafast laser pulses have been demonstrated and future plans include using these pulses to generate controlled-phase gates between two ions on sub-microsecond time scale.