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This Defense Intelligence Reference Document from the Defense Intelligence Agency, dated 10 December 2010, is one of a series of advanced technology reports produced in FY 2010 under the Advanced Aerospace Weapon System Applications (AAWSA) Program. It reviews quantum computing technologies and DNA-based molecular computing for onboard supercomputing on future spacecraft. It forecasts ion-trap quantum computers within 10 years, simple DNA tile computing within 20 years, and self-repairing DNA computers on a 40-year horizon.
“The Advance”7 pages
UNCLASSIFIED/ /F9R 8Pflll.t.k WCE ODIi X Quantum Dots in Graphene Nanoribbons Graphene ribbons are one dimensional stripes of graphene. They can be considered as unfolded carbon nanotubes. Graphene ribbons were proposed by Nakada et al in 1996 (52). Nakada used the same single orbital tight-binding model that successfully portrays two- dimensional graphene as a semimetal; graphene ribbons are either metallic or semiconducting depending on their crystallographic orientation and width. More realistic calculations using the Hubbard model in a mean field approximation and density functional calculations show that zigzag ribbons are insulating due to the magnetization of their edges with opposite spin orientation in each edge. It has been found that this anti-ferromagnetic insulator phase has a hidden underlying ferroelectric order that can be described as excitonic insulator whose order parameter is the spin-resolved dipole operator, the analog of the spin current operator (53). Long (gl μm) graphene nanoconstrictions display gapped behavior: conduction is suppressed by several orders of magnitude for a wide range of gate voltages around the Dirac point, and for tens of millivolts of source-drain bias (54) (55). 15 Figure 2. Quantum dot in graphene nanoribbon. A ribbon of graphene with semi-conducting armchair boundaries is schematically shown. Two barrier gates (blue) define the rectangular size of the quantum dot (with width Wand length L). A back gate (red) allows one to shift the energy levels in the dot. Two or more quantum dots of this type can be easily put in series in a single nanoribbon. UNCLASSIFIED/ }F&R: 8ffll1Jllt ~!JE! Silt I
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Report, from the dia collection. The PDF is mirrored here; the original link is above. 54 pages are in the text index: search them above, or from the library's search.