121 research outputs found
Adiabatic Quantum Computation with a 1D projector Hamiltonian
Adiabatic quantum computation is based on the adiabatic evolution of quantum
systems. We analyse a particular class of qauntum adiabatic evolutions where
either the initial or final Hamiltonian is a one-dimensional projector
Hamiltonian on the corresponding ground state. The minimum energy gap which
governs the time required for a successful evolution is shown to be
proportional to the overlap of the ground states of the initial and final
Hamiltonians. We show that such evolutions exhibit a rapid crossover as the
ground state changes abruptly near the transition point where the energy gap is
minimum. Furthermore, a faster evolution can be obtained by performing a
partial adiabatic evolution within a narrow interval around the transition
point. These results generalize and quantify earlier works.Comment: revised versio
General framework for quantum search algorithms
Grover's quantum search algorithm drives a quantum computer from a prepared
initial state to a desired final state by using selective transformations of
these states. Here, we analyze a framework when one of the selective
trasformations is replaced by a more general unitary transformation. Our
framework encapsulates several previous generalizations of the Grover's
algorithm. We show that the general quantum search algorithm can be improved by
controlling the transformations through an ancilla qubit. As a special case of
this improvement, we get a faster quantum algorithm for the two-dimensional
spatial search.Comment: revised versio
A Stepwise Planned Approach to the Solution of Hilbert's Sixth Problem. III : Measurements and von Neumann Projection/Collapse Rule
Supmech, the universal mechanics developed in the previous two papers,
accommodates both quantum and classical mechanics as subdisciplines (a brief
outline is included for completeness); this feature facilitates, in a supmech
based treatment of quantum measurements, an unambiguous treatment of the
apparatus as a quantum system approximated well by a classical one. Taking
explicitly into consideration the fact that observations on the apparatus are
made when it has `settled down after the measurement interaction' and are
restricted to macroscopically distinguishable pointer readings, the unwanted
superpositions of (system + apparatus) states are shown to be suppressed; this
provides a genuinely physics based justification for the (traditionally
\emph{postulated}) von Neumann projection/collapse rule. The decoherence
mechanism brought into play by the stated observational constraints is free
from the objections against the traditional decoherence program.Comment: 29 pages; one section and two references added; results unchange
Critically damped quantum search
Although measurement and unitary processes can accomplish any quantum
evolution in principle, thinking in terms of dissipation and damping can be
powerful. We propose a modification of Grover's algorithm in which the idea of
damping plays a natural role. Remarkably, we have found that there is a
critical damping value that divides between the quantum and
classical O(N) search regimes. In addition, by allowing the damping to vary in
a fashion we describe, one obtains a fixed-point quantum search algorithm in
which ignorance of the number of targets increases the number of oracle queries
only by a factor of 1.5
Conservation Agriculture for Food Security and Climate Resilience in Nepal
Achieving the sustainable development goals of the United Nations requires innovations in agriculture and development of climate-smart and economically feasible approaches for smallholder farmers in developing countries. Historical climate data of Nepal, which include 116 yr since 1901, has shown an increasing trend for average temperature by 0.016 ˚C yr–1 whereas precipitation has shown a decreasing trend by 0.137 mm yr–1. Such weather trends could enhance glacier melt associated flooding, and delayed monsoon rainfalls negatively impacting the agricultural production. The Nepalese government is promoting conservation agriculture (CA) through development of low-cost technologies that can be used effectively in difficult terrains. Such techniques include crop diversification, crop rotation, cover crops, and minimum tillage; all of which can reduce soil degradation. In addition, increasing crop residue retention can result in greater C sequestration and crop yield and reductions in greenhouse gas emissions. However, there is still lack of consensus on the merits of CA in the context of smallholder farming systems in Nepal. This paper reviews existing literature and provides an overview of farming practices in Nepal, highlights near-term challenges associated with climate change and food security, and discusses the role of CA as a climate-smart strategy to minimize soil degradation and improve food security
Winter Wheat Quality Responses to Water, Environment, and Nitrogen Fertilization
Decreasing carbon (C) footprints by reducing nitrogen (N) and water inputs has been speculated to have negative impacts on wheat grain yield and flour processing quality. The objective of this study was to determine the impact of N and water stress on winter wheat grain yield, protein composition, and dough quality. Wheat fertilized at two N rates (unfertilized and recommended) was grown under water-stressed and well-watered environments. Nitrogen and water stress were measured using the 13C isotopic approach. Research showed that (1) N fertilizer and the water-management environment produced similar impacts on wheat quality and yield loss due to N stress and yield loss due to water stress (YLWS); (2) N fertilizer increased flour protein, dough stability, and relative concentration of glutenin (%Glu), unextractable polymeric protein (UPP), and relative amount of high-molecular-weight glutenin subunits (HMW-GS/LMW-GS); (3) the well-watered environment reduced protein contents when N mineralization was low, whereas it did not influence protein content when mineralization was high; and (4) the %Glu was negatively correlated with yield loss due to N stress (YLNS) and positively correlated with stability. This study showed that a clear understanding of the complex relationship between soil variability and climatic conditions should make it possible to develop adaptive management practices, increase profitability, and improve quality
Soil and Land-Use Change Sustainability in the Northern Great Plains of the USA
In the Northern Great Plains (NGP), the combined impacts of land-use and climate variability have the potential to place many soils on the tipping point of sustainability. The objectives of this study were to assess if the conversion of grassland to croplands occurred on fragile landscapes in the North America Northern Great Plains. South Dakota and Nebraska were selected for this study because they are located in a climate transition zone. We visually classified 43,200 and 38,400 points in South Dakota and Nebraska, respectively, from high-resolution imagery in 2006, 2012, and 2014 into five different categories (cropland, grassland, habitat, NonAg, and water). The sustainability risk of the land-use changes was assessed based on the land capability class (LCC) scores at the selected sites. Sites with LCC scores ≤ 4 are considered sustainable for crop production if appropriate management practices are followed. Scores ≥ 6 are not considered suitable for row crop production. From 2006 to 2014, 910,000 and 360,000 ha of land were converted from grassland to cropland in South Dakota and Nebraska, respectively. Approximately 92 and 80% of the grassland conversion to croplands occurred on land suitable for crop production (land capability class, LCC ≤ 4) in South Dakota and Nebraska, respectively
New Developments in Quantum Algorithms
In this survey, we describe two recent developments in quantum algorithms.
The first new development is a quantum algorithm for evaluating a Boolean
formula consisting of AND and OR gates of size N in time O(\sqrt{N}). This
provides quantum speedups for any problem that can be expressed via Boolean
formulas. This result can be also extended to span problems, a generalization
of Boolean formulas. This provides an optimal quantum algorithm for any Boolean
function in the black-box query model.
The second new development is a quantum algorithm for solving systems of
linear equations. In contrast with traditional algorithms that run in time
O(N^{2.37...}) where N is the size of the system, the quantum algorithm runs in
time O(\log^c N). It outputs a quantum state describing the solution of the
system.Comment: 11 pages, 1 figure, to appear as an invited survey talk at MFCS'201
A quantum genetic algorithm with quantum crossover and mutation operations
In the context of evolutionary quantum computing in the literal meaning, a
quantum crossover operation has not been introduced so far. Here, we introduce
a novel quantum genetic algorithm which has a quantum crossover procedure
performing crossovers among all chromosomes in parallel for each generation. A
complexity analysis shows that a quadratic speedup is achieved over its
classical counterpart in the dominant factor of the run time to handle each
generation.Comment: 21 pages, 1 table, v2: typos corrected, minor modifications in
sections 3.5 and 4, v3: minor revision, title changed (original title:
Semiclassical genetic algorithm with quantum crossover and mutation
operations), v4: minor revision, v5: minor grammatical corrections, to appear
in QI
Analysis of Blunt Abdominal Trauma with Respect to Associated Injuries, Period of Survival And Mechanism of Death Among Autopsies Conducted in Dept. of FMT, RIMS, Ranchi
Abstract : Introduction: Since the abdominal cavity contains the vital organs like liver, spleen, kidney, stomach, intestines etc, traum
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