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Kirkland, WA, United States

Shu G.,University of Washington | Shu G.,Georgia Institute of Technology | Chou C.-K.,University of Washington | Kurz N.,University of Washington | And 4 more authors.
Journal of the Optical Society of America B: Optical Physics | Year: 2011

Trapped, laser-cooled atoms and ions produce intense fluorescence of the order 107 ~ 108 photons per second. Detection of this fluorescence enables efficient measurement of the quantum state of qubits based on trapped atoms. It is desirable to collect a large fraction of the photons to make the detection faster and more reliable. Additionally, efficient fluorescence collection can improve the speed and fidelity of remote ion entanglement and quantum gates. Refractive and reflective optics, and optical cavities have all been used to collect the trapped ion fluorescence with up to about 10% efficiency. Here we show a novel ion trap design that incorporates a metallic spherical mirror as the integral part of the trap itself, being its RF electrode. The mirror geometry enables up to 35% solid angle collection of trapped ion fluorescence. The movable central pin electrode of this trap allows precise placement of the ion at the focus of the reflector. We characterize the performance of the mirror, and measure 25% collection efficiency, likely limited by the imperfections of the mirror surface. We also study the properties of the images of single ions formed by the spherical mirror and apply aberration correction with an aspherical element placed outside the vacuum system. Owing to the simplicity of its design, this trap structure can be adapted for microfabrication and integration into more complex trap architectures. © 2011 Optical Society of America.

Lovejoy T.C.,University of Washington | Lovejoy T.C.,Nion Company | Yitamben E.N.,University of Washington | Yitamben E.N.,Argonne National Laboratory | And 3 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2011

The growth and phase segregation properties of the potential dilute magnetic semiconductor alloy (MnSe)x(Ga2/3Se) 1-x are studied as a function of thickness, Mn concentration, postgrowth annealing, and the presence or absence of undoped Ga 2Se3 buffer and capping layers. This system is an unusual case in heteroepitaxy where two-phase MnSe+Ga2Se3 has better lattice matching than the (MnSe)x(Ga2/3Se) 1-x alloy. Despite this peculiarity, this system shows a modified form of Stranski-Krastonow growth: laminar films are observed up to a certain x-dependent critical thickness, above which islands are observed by scanning tunneling microscopy. The island morphology depends on the presence or absence of an undoped Ga2Se3 buffer layer and postgrowth annealing. A kinetically stabilized platelet morphology is observed at the crossover point between laminar and islanded films. Based on Mn and Se K-edge extended x-ray absorption fine structure and x-ray absorption near-edge structure spectroscopy, there are two types of Mn in islanded films: Mn that remains doped in the Ga2Se3 but oxidizes upon exposure to air, and Mn that participates in the islands, which are precipitates of the MnSe phase. Consistent with MnO or MnSe, L-edge x-ray absorption on air-exposed films suggests the Mn is in the formal +2 oxidation state. No L-edge x-ray magnetic circular dichroism signal is observed at 20 K, which may be due to surface effects or to a lack of magnetic order. © 2011 American Physical Society.

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The front cover of Nature from March 25th, 2010. The image on the cover was acquired using a Nion microscope, in a collaborative project between Nion, ORNL, Oxford University and Vanderbilt University ...

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About Us Nion is a world-class developer of advanced scanning transmission electron microscopes and other electron-optical instruments. We work in close collaboration with our customers, developing instruments that answer real needs in the real world ...

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