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The spatial manipulation of ionic qubits in a fast and precise fashion is one of the foremost issues in scalable quantum information processing with trapped ions. We report our recent efforts toward precise manipulation of trapped ions, including separation, recombination and reordering of the ions, in our home-made microscopic surface-electrode trap. We also demonstrate the micromotion compensation for the trapped ions by rf-photon cross-correlation, which ensures the cooling of the ions down to the temperature 23.3mK. [ABSTRACT FROM AUTHOR]

40Ca+ ions are successfully confined, under the cooling of a red-detuned laser, in a home-built microscopic surface-electrode (MSE) trap. With all electrodes deposited on a low-rf-loss substrate, our 500- µm-scale MSE trap is designed involving three potential wells and manufactured by the standard technique of the printed circuit board. Both linear and two-dimensional crystals of 40Ca+ are observed in the trap after preliminary micromotion compensation is carried out. The development of the MSE trap aims at large-scale trapped-ion quantum information processing. [ABSTRACT FROM AUTHOR]

In this paper we try to develop a scalable surface-electrode architecture for ion trap quantum information processing. The confinement of the ions by the rf pseudopotential and the movement of the ions by changing the rf pseudopotential are investigated by numerical simulation. Particular concern is paid to the +-shaped junction, which is the connection of different components of the architecture, and also on the place which yields heat and escaping ions. We show the feasibility of fabricating and operating on the architecture for quantum information processing with currently available technology. [ABSTRACT FROM AUTHOR]

We demonstrate experimentally the Doppler cooling of 40Ca+ ions using the s1/2 → D3/2 electric quadrupole transition, in which the scattering light that is much different from the exciting light makes it possible to collect background-free fluorescence. The idea excluding 397nm excitation has the advantage of high-sensitivity detection and only employs lasers in red and infrared wavelengths, which should be practical for trapped-ion quantum information processing. [ABSTRACT FROM AUTHOR]

By using the special maskless V-grooved c-plane sapphire as the substrate, we previously developed a novel GaN LEO method, or the so-called canti-bridge epitaxy (CBE), and consequently wing-tilt-free GaN films were obtained with low dislocation densities, with which all the conventional difficulties can be overcome [J. Vacuum Sci. Technol. B 23 (2005) 2476]. Here the evolution manner of dislocations in the CBE GaN films is investigated using transmission electron microscopy. The mechanisms of dislocation reduction are discussed. Dislocation behaviour is found to be similar to that in the conventional LEO GaN films except the enhanced dislocation-combination at the coalescence boundary that is a major dislocation-reduction mechanism for the bent horizontal-propagating dislocations in the CBE GaN films. The enhancement of this dislocation-combination probability is believed to result from the inclined shape and the undulate morphology of the sidewalls, which can be readily obtained in a wide range of applicable film-growth conditions during the GaN CBE process. Further development of the GaN CBE method and better crystal-quality of the GaN film both are expected. [ABSTRACT FROM AUTHOR]

We investigate the spectra of the electric quadrupole 42S1/2→32D5/2 transitions in a single 40Ca+ ion confined in a home-built linear trap. We probe the transitions with an ultra-narrow bandwidth laser at 729 nm. In a weak magnetic field, the quadrupole transition splits into ten components with the maximal line strength proportional to their squared Clebsch—Gordan factors. In a magnetic field of the order of Gauss, the observed equidistant sideband reflects the Zeeman substructure modulated by the quantized oscillation due to the secular motion in the trap. The temperature of the trapped ion can be determined by the envelope of the sideband spectrum. We also demonstrate the Rabi oscillation in a carrier transition after the ion has been Doppler cooled, which can be fitted by the model with the thermal state of motion. [ABSTRACT FROM AUTHOR]

The stable confinement of ions in an electromagnetic trap is a prerequisite of sideband cooling and quantum information processing. For a string of ions in a linear ion trap, we report our recent efforts of compensating for micromotion of the ions by three methods, which yields narrower fluorescence spectra and lower temperature. We also achieve a photoionization scheme that loads the ions deterministically into the linear trap from an atomic beam. [ABSTRACT FROM AUTHOR]