4,820 research outputs found
A Robust Quantum Random Access Memory
A "bucket brigade" architecture for a quantum random memory of memory
cells needs times of quantum manipulation on control circuit nodes
per memory call. Here we propose a scheme, in which only average times
manipulation is required to accomplish a memory call. This scheme may
significantly decrease the time spent on a memory call and the average overall
error rate per memory call. A physical implementation scheme for storing an
arbitrary state in a selected memory cell followed by reading it out is
discussed.Comment: 5 pages, 3 figure
Many-body Green's function theory of ferromagnetic Heisenberg systems with single-ion anisotropies in more than one direction
The behaviour of ferromagnetic systems with single-ion anisotropies in more
than one direction is investigated with many-body Green's function theory
generalizing earlier work with uniaxial anisotropies only. It turns out to be
of advantage to construct Green's functions in terms of the spin operators S^x,
S^y and S^z, instead of the commonly used S^+,S^- and S^z operators. The
exchange energy terms are decoupled by RPA and the single-ion anisotropy terms
by a generalization of the Anderson-Callen decoupling. We stress that in the
derivation of the formalism none of the three spatial axes is special, so that
one is always able to select a reference direction along which a magnetization
component is not zero. Analytical expressions are obtained for all three
components of the magnetization and the expectation values ,
and for any spin quantum number S. The formalism considers both
in-plane and out-of-plane anisotropies. Numerical calculations illustrate the
behaviour of the magnetization for 3-dimensional and 2-dimensional systems for
various parameters. In the 2-dimensional case, the magnetic dipole-dipole
coupling is included, and a comparison is made between in-plane and
out-of-plane anisotropies.Comment: 16 pages, 8 figures, missing figures adde
Study on the Realization of Freshwater Ecosystem Services from the Perspective of Consumer Willingness to Pay in China
The realization of freshwater ecosystem services value plays a vital role in the survival of human beings and the sustainable development of fisheries, and this process is inseparable from the support of consumers. This paper decomposes freshwater ecosystem services in multiple dimensions. From the perspective of consumers' willingness to pay for ecosystem services, using the survey data of 821 consumers in China, the influence of various dimensions of freshwater ecosystem services on consumers' willingness is explored by the structural equation model. The results show that: (1) consumers already have a certain awareness of freshwater ecosystem services, but the proportion of consumers willing to pay extra for them is not high; (2) the individual characteristics (age, gender, education, and income ) affect consumersâ willingness to pay for freshwater ecosystem services value, but the impact degree is not high; (3) regulating, cultural, and provisional servers functions of freshwater ecosystem services significantly affect consumersâ willingness to pay, especially freshwater ecosystem servicesâ role on regulating carbon emissions, controlling algal biomass, enhancing local fishery culture and improving leisure and leisure entertainment services. This study is helpful to deeply understand consumers' willingness to pay for various dimensions of freshwater ecosystem services and provide more targeted and detailed guidance for realizing it
Bituminous Coal Combustion with New Insights
As one of the most important primary energy, bituminous coal has been widely applied in many fields. The combustion studies of bituminous coal have attracted a lot of attention due to the releases of hazardous emissions. This work focuses on the investigation of combustion characteristics of Shenmu bituminous pulverized coal as a representative bituminous coal in China with a combined TG-MS-FTIR system by considering the effect of particle size, heating rate, and the total flow rate. The combustion products were accurately quantified by normalization and numerical analysis of MS results. The results indicate that the decrease of the particle size, heating rate, and the total flow rate result in lower ignition and burnout temperatures. The activation energy tends to be lower with smaller particle size, faster heating rate, and lower total flow rate. The MS and FTIR results demonstrate that lower concentrations of different products, such as NO, NO2, HCN, CH4, and SO2, were produced with smaller particle size, slower heating rate, and lower total flow rate. This work will guide to understand the combustion kinetics of pulverized coals and be beneficial to control the formation of pollutants
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