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[en] We study entanglement dynamics of two and three atoms stored in a common nonperfect cavity together with some other nonentangled atoms. It is guessed at first thought that the presence of nonentangled atoms would favor the decoherence process of the interested entangled atoms. We show, on the contrary, that it is not so. Namely, as results of a rigorous nonperturbative analysis, disentanglement rate of the interested atoms decreases with the increase of the number of nonentangled atoms. If the number of nonentangled atoms is sufficiently large, the entanglement of interested atoms could be protected efficiently.
[en] Micromechanical sensing of magnetic force was used to detect nuclear magnetic resonance with exceptional sensitivity and spatial resolution. With a 900 angstrom thick silicon nitride cantilever capable of detecting subfemtonewton forces, a single shot sensitivity of 1.6 x 1013 protons was achieved for an ammonium nitrate sample mounted on the cantilever. A nearby millimeter-size iron particle produced a 600 tesla per meter magnetic field gradient, resulting in a spatial resolution of 2.6 micrometers in one dimension. These results suggest that magnetic force sensing is a viable approach for enhancing the sensitivity and spatial resolution of nuclear magnetic resonance microimaging
[en] Electron spin resonance (ESR) dating can be applied to a wide range of materials and has probably the largest potential amongst the dating techniques for the Quaternary. The dating procedure is very complex and many problems have to be addressed before this method can be regarded as a routine dating technique. This contribution gives a short introduction to ESR dating and tries to outline the specific advantages of this dating method, but also give a very personal opinion about the problems that need attention. It focuses on the actual ESR part of the dating procedure: signal definition and accumulated dose estimation. (author)
[en] In this letter, we describe a unique method of producing hyperthermal neutrals for material processing. The hyperthermal neutrals are produced by accelerating ions across a sheath from a plasma onto a surface. On impact, the ions are neutralized and reflected with ∼50% of their incident energy. These neutrals then bounce off of additional surfaces prior to impacting the target. This unique multiple bounce system was developed for the following reasons: to reduce contamination from sputtered surface material, improve beam uniformity, and reduce UV radiation in the beam path. As a test of this method, we built a prototype beam source and used it to ash photoresist at rates up to 0.022 μm/min. These rates are consistent with a predicted neutral beam flux, 2x1014cm-2s-1. In addition, a simple model is used to indicate that this method is capable of producing economically acceptable ash rates. Comparisons with other neutral-beam production methods are made. copyright 1997 American Institute of Physics