5 research outputs found
Quantum cellular automata quantum computing with endohedral fullerenes
We present a scheme to perform universal quantum computation using global
addressing techniques as applied to a physical system of endohedrally doped
fullerenes. The system consists of an ABAB linear array of Group V endohedrally
doped fullerenes. Each molecule spin site consists of a nuclear spin coupled
via a Hyperfine interaction to an electron spin. The electron spin of each
molecule is in a quartet ground state . Neighboring molecular electron
spins are coupled via a magnetic dipole interaction. We find that an
all-electron construction of a quantum cellular automata is frustrated due to
the degeneracy of the electronic transitions. However, we can construct a
quantum celluar automata quantum computing architecture using these molecules
by encoding the quantum information on the nuclear spins while using the
electron spins as a local bus. We deduce the NMR and ESR pulses required to
execute the basic cellular automata operation and obtain a rough figure of
merit for the the number of gate operations per decoherence time. We find that
this figure of merit compares well with other physical quantum computer
proposals. We argue that the proposed architecture meets well the first four
DiVincenzo criteria and we outline various routes towards meeting the fifth
criteria: qubit readout.Comment: 16 pages, Latex, 5 figures, See http://planck.thphys.may.ie/QIPDDF/
submitted to Phys. Rev.
Charge Transfer Doping of Silicon
We demonstrate a novel doping mechanism of silicon, namely n type transfer doping by adsorbedorganic cobaltocene CoCp2 molecules. The amount of transferred charge as a function of coverage is monitored by following the ensuing band bending via surface sensitive core level photoelectron spectroscopy. The concomitant loss of electrons in the CoCp2 adlayer is quantified by the relative intensities of chemically shifted Co2p components in core level photoelectron spectroscopy which correspond to charged and neutral molecules. Using a previously developed model for transfer doping, the evolution in relative intensities of the two components as a function of coverage has been reproduced successfully. A single, molecule specific parameter, the negative donor energy of amp; 8722; 0.50 0.15 eV suffices to describe the self limiting doping process with a maximum areal density of transferred electrons of 2 1013 cm amp; 8722;2 in agreement with the measured downward band bending. The advantage of this doping mechanism over conventional doping for nanostructures is addresse
Semi-endogenous versus Schumpeterian growth models: testing the knowledge production function using international data
Schumpeterian growth theory, Semi-endogenous growth theory, O3, O4,
R&D, International Trade and Creative Destruction—Empirical Findings from Finnish Manufacturing Industries*
The determinants of productivity-enhancing micro-level restructuring are examined empirically with a panel of the twelve Finnish manufacturing industries. It is hypothesized that R&D leads to productivity diversity among plants, which in turn leads to the gradual reshuffling of input shares in the presence of dynamic competitive pressure. The effect of the “creative destruction” on industry productivity growth is measured with the between-component of productivity decomposition. Econometric results indicate with reasonable robustness that R&D generates creative destruction with a lag of several years. Some evidence is found that imports stimulate productivity-enhancing restructuring, especially when domestic R&D is low. Copyright Springer Science + Business Media, Inc. 2005R&D, competition, international trade, productivity, plant-level restructuring,