11,623 research outputs found
Adiabatic quantum algorithm for search engine ranking
We propose an adiabatic quantum algorithm for generating a quantum pure state
encoding of the PageRank vector, the most widely used tool in ranking the
relative importance of internet pages. We present extensive numerical
simulations which provide evidence that this algorithm can prepare the quantum
PageRank state in a time which, on average, scales polylogarithmically in the
number of webpages. We argue that the main topological feature of the
underlying web graph allowing for such a scaling is the out-degree
distribution. The top ranked entries of the quantum PageRank state
can then be estimated with a polynomial quantum speedup. Moreover, the quantum
PageRank state can be used in "q-sampling" protocols for testing properties of
distributions, which require exponentially fewer measurements than all
classical schemes designed for the same task. This can be used to decide
whether to run a classical update of the PageRank.Comment: 7 pages, 5 figures; closer to published versio
The Local Emergence and Global Diffusion of Research Technologies: An Exploration of Patterns of Network Formation
Grasping the fruits of "emerging technologies" is an objective of many
government priority programs in a knowledge-based and globalizing economy. We
use the publication records (in the Science Citation Index) of two emerging
technologies to study the mechanisms of diffusion in the case of two innovation
trajectories: small interference RNA (siRNA) and nano-crystalline solar cells
(NCSC). Methods for analyzing and visualizing geographical and cognitive
diffusion are specified as indicators of different dynamics. Geographical
diffusion is illustrated with overlays to Google Maps; cognitive diffusion is
mapped using an overlay to a map based on the ISI Subject Categories. The
evolving geographical networks show both preferential attachment and
small-world characteristics. The strength of preferential attachment decreases
over time, while the network evolves into an oligopolistic control structure
with small-world characteristics. The transition from disciplinary-oriented
("mode-1") to transfer-oriented ("mode-2") research is suggested as the crucial
difference in explaining the different rates of diffusion between siRNA and
NCSC
- …