6 research outputs found
High-efficiency quantum interrogation measurements via the quantum Zeno effect
The phenomenon of quantum interrogation allows one to optically detect the
presence of an absorbing object, without the measuring light interacting with
it. In an application of the quantum Zeno effect, the object inhibits the
otherwise coherent evolution of the light, such that the probability that an
interrogating photon is absorbed can in principle be arbitrarily small. We have
implemented this technique, demonstrating efficiencies exceeding the 50%
theoretical-maximum of the original ``interaction-free'' measurement proposal.
We have also predicted and experimentally verified a previously unsuspected
dependence on loss; efficiencies of up to 73% were observed and the feasibility
of efficiencies up to 85% was demonstrated.Comment: 4 pages, 3 postscript figures. To appear in Phys. Rev. Lett;
submitted June 11, 199
Growth mechanism of iron-filled carbon nanotubules
Iron-filled nanotubules were synthesized in a carbon are in the presence of He and Fe(CO)(5) gases. The consumption of the Fe(CO)(5) inside the are chamber was controlled by the pressure of the pentacarbonyliron Fe(CO)(5) gas. Different shapes and filling extents of nanotubules were found depending on the pentacarbonyliron concentration supplied. Based on high-resolution transmission electron microscope images, we propose a growth model of iron-filled carbon nanotubules. The growth proceeds through the deposition and surface diffusion of carbon on the liquidlike metal. The hollow tubules probably grow spontaneously. (C) 1996 American Institute of Physics