31,103 research outputs found
Interference Automata
We propose a computing model, the Two-Way Optical Interference Automata
(2OIA), that makes use of the phenomenon of optical interference. We introduce
this model to investigate the increase in power, in terms of language
recognition, of a classical Deterministic Finite Automaton (DFA) when endowed
with the facility of optical interference. The question is in the spirit of
Two-Way Finite Automata With Quantum and Classical States (2QCFA) [A. Ambainis
and J. Watrous, Two-way Finite Automata With Quantum and Classical States,
Theoretical Computer Science, 287 (1), 299-311, (2002)] wherein the classical
DFA is augmented with a quantum component of constant size. We test the power
of 2OIA against the languages mentioned in the above paper. We give efficient
2OIA algorithms to recognize languages for which 2QCFA machines have been shown
to exist, as well as languages whose status vis-a-vis 2QCFA has been posed as
open questions. Finally we show the existence of a language that cannot be
recognized by a 2OIA but can be recognized by an space Turing machine.Comment: 19 pages. A preliminary version appears under the title "On a Model
of Computation based on Optical Interference" in Proc. of the 16-th
Australasian Workshop on Combinatorial Algorithms (AWOCA'05), pp. 249-26
Bounding Run-Times of Local Adiabatic Algorithms
A common trick for designing faster quantum adiabatic algorithms is to apply
the adiabaticity condition locally at every instant. However it is often
difficult to determine the instantaneous gap between the lowest two
eigenvalues, which is an essential ingredient in the adiabaticity condition. In
this paper we present a simple linear algebraic technique for obtaining a lower
bound on the instantaneous gap even in such a situation. As an illustration, we
investigate the adiabatic unordered search of van Dam et al. (How powerful is
adiabatic quantum computation? Proc. IEEE FOCS, pp. 279-287, 2001) and Roland
and Cerf (Physical Review A 65, 042308, 2002) when the non-zero entries of the
diagonal final Hamiltonian are perturbed by a polynomial (in , where
is the length of the unordered list) amount. We use our technique to derive
a bound on the running time of a local adiabatic schedule in terms of the
minimum gap between the lowest two eigenvalues.Comment: 11 page
Geology and geochemistry of the Middle Proterozoic Eastern Ghat mobile belt and its comparison with the lower crust of the Southern Peninsular shield
Two prominent rock suites constitute the lithology of the Eastern Ghat mobile belt: (1) the khondalite suite - the metapelites, and (2) the charnockite suite. Later intrusives include ultramafic sequences, anorthosites and granitic gneisses. The chief structural element in the rocks of the Eastern Ghats is a planar fabric (gneissosity), defined by the alignment of platy minerals like flattened quartz, garnet, sillimanite, graphite, etc. The parallelism between the foliation and the lithological layering is related to isoclinal folding. The major structural trend (axial plane foliation trend) observed in the belt is NE-SW. Five major tectonic events have been delineated in the belt. A boundary fault along the western margin of the Eastern Ghats, bordering the low grade terrain has been substantiated by recent gravity and the deep seismic sounding studies. Field evidence shows that the pyroxene granulites (basic granulites) post-date the khondalite suite, but are older than the charnockites as well as the granitic gneisses. Polyphase metamorphism, probably correlatable with different periods of deformation is recorded. The field relations in the Eastern Ghats point to the intense deformation of the terrain, apparently both before, during and after metamorphism
Quantitative mapping of rainfall rates over the oceans utilizing Nimbus-5 ESMR data
The electrically scanning microwave radiometer (ESMR) data from the Nimbus 5 satellite was used to deduce estimates of precipitation amount over the oceans. An atlas of the global oceanic rainfall was prepared and the global rainfall maps analyzed and related to available ground truth information as well as to large scale processes in the atmosphere. It was concluded that the ESMR system provides the most reliable and direct approach yet known for the estimation of rainfall over sparsely documented, wide oceanic regions
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