A 3D topological insulator quantum dot for optically controlled quantum memory and quantum computing

We present the model of a quantum dot (QD) consisting of a spherical core-bulk heterostructure made of 3D topological insulator (TI) materials, such as PbTe/Pb$_{0.31}$Sn$_{0.69}$Te, with bound massless and helical Weyl states existing at the interface and being confined in all three dimensions. The number of bound states can be controlled by tuning the size of the QD and the magnitude of the core and bulk energy gaps, which determine the confining potential. We demonstrate that such bound Weyl states can be realized for QD sizes of few nanometers. We identify the spin locking and the Kramers pairs, both hallmarks of 3D TIs. In contrast to topologically trivial semiconductor QDs, the confined massless Weyl states in 3D TI QDs are localized at the interface of the QD and exhibit a mirror symmetry in the energy spectrum. We find strict optical selection rules satisfied by both interband and intraband transitions that depend on the polarization of electron-hole pairs and therefore give rise to the Faraday effect due to Pauli exclusion principle. We show that the semi-classical Faraday effect can be used to read out spin quantum memory. When a 3D TI QD is embedded inside a cavity, the single-photon Faraday rotation provides the possibility to implement optically mediated quantum teleportation and quantum information processing with 3D TI QDs, where the qubit is defined by either an electron-hole pair, a single electron spin, or a single hole spin in a 3D TI QD. Remarkably, the combination of inter- and intraband transition gives rise to a large dipole moment of up to 450 Debye. Therefore, the strong-coupling regime can be reached for a cavity quality factor of $Q\approx10^{4}$ in the infrared wavelength regime of around $10\:\mu$m.Comment: 19 pages, 11 figures, RevTe

MEETING THE KYOTO TARGET THROUGH CONSERVATION TILLAGE AND ITS IMPLICATION FOR NATURAL CAPITAL MAINTENANCE, PRODUCTION EFFICIENCY, AND SUSTAINABILITY

According to Article 3.4 of the Kyoto Protocol, agricultural soil could be used as a sink for carbon sequestration and hence it may provide an alternative venue to sequester the greenhouse gas emission. US plans to reduce the carbon emission amount by seven percent below the 1990 level within the target date of 2008-2012. The major approaches to achieve the goal targeted by Kyoto Protocol in US are through fossil fuel tax and increasing forest area by afforestation. This means fossil fuel price will increase which will have a direct impact to conventional tillage cost. As a result farmers would be motivated to use less machinery operation in farming and hence may use conservation tillage in farming practices. Rather than cause and effect relationship created by fuel price increase, conservation tillage itself has been considered as a method suggested to increase carbon sequestration. We analyze the economic and environmental roles of conservation tillage in carbon sequestration. The use of conservation tillage helps to sequester carbon in the form of soil organic matter. We examined the potential of conservation tillage in sequestering carbon and its role in increasing soil natural capital and thus the productivity of soil. We then used the concept of production efficiency to calculate the benefits of soil carbon sequestration using sustainability criteria. The detail of carbon sequestration and soil natural capital buildup were demonstrated using conservation tillage practiced in cotton production in Georgia. Four systems of conservation tillage encompassing both chemical and organic source of plant nutrients were compared for their capacity to sequester carbon. Organic matter buildups were faster in a system with conservation tillage and organic sources of nutrient compared to conventional tillage. Result indicated that in a system with a slow buildup of natural capital, production efficiency was not significant. This has resulted the system to be unprofitable in the short run and unsustainable in the long run. The system with a high amount of organic matter increases the production efficiency of applied inputs and also plays an important role in substituting chemical fertilizers. Alternative tillage management systems were evaluated for their sustainability using total factor productivity. It was found that conservation tillage meets criteria of sustainability more often than the management system containing conventional tillage. Conservation tillage was found to be the best alternative not only to sequester carbon but also developing natural capital-based sustainable system.Kyoto protocol, Carbon sequestration, Natural capital, Production efficiency, Sustainability, Environmental Economics and Policy, Productivity Analysis,

ECONOMIC EFFECT OF IMPERFECT INFORMATION ON CONSERVATION DECISIONS

Cotton farmers in the Piedmont region incorrectly believe conservation systems with winter cover crop and no-till cultivation yield less than conventional systems. We model the effect of organic matter on productivity and show how ignoring this effect causes returns to be underestimated. Farmers with imperfect information underinvest in residue management.residue management, organic matter, productivity, comparative statics, Farm Management, Land Economics/Use, Productivity Analysis,

Factors Affecting the Decision to Adopt and Continue Best Management Practices by Broiler Producers

We analyzed survey data collected from broiler producers in Louisiana to understand the factors affecting the longevity of best management practices adoption. Results indicated variables such as future expansion potential and the length of time the farm have been with the family decreases the chance of adopting best management practices. Our results support the idea that education and income would have positive results on the entry decision to adopt best management practices.adoption, best management practices, broiler production, entry, exit, Farm Management, Livestock Production/Industries,

PART TIME FARMING, FARM PRODUCTIVITY, AND FARM INCOME: EVIDENCE FROM THE SOUTHEAST US

We analyzed the effect of part time farming in the US using a panel data analysis method. Data from three census years on ten southern states and the counties therein indicated that part time farming has a positive impact on the total value of the farm products produced. Although the result is preliminary, it sheds an important light on the changing farm structure in the USA.Agricultural Finance,

PRODUCTION TERMINATION AS AN ALTERNATIVE TO MITIGATE NUTRIENT POLLUTION

Nutrient runoff from agricultural land can be reduced through production termination to mitigate water pollution. The willingness to accept value to terminate the broiler production is evaluated using sample selection model. The result showed a positive relationship between the decision to participation and stated WTA value indicating the producers are willing to terminate the production but at high cost. The farmer’s perception about government role on water pollution, farm income, information and awareness about other pollution reduction alternatives play a major role on stated WTA amount as well as on participation decision.Environmental Economics and Policy,

DYNAMIC ECONOMIC ANALYSIS OF A RESIDUE MANAGEMENT SYSTEM IN COTTON

Residue management system (RMS), comprised of no till cultivation, a winter cover crop, and poultry litter, could be an alternative to existing management system in cotton production in the Georgian Piedmont. We compare the productivity and profitability of RMS with the current system over time, focusing on the role of organic matter. Using dynamic bioeconomic modelling technique, we show that the net return and land value difference between these two systems increase as the terminal period increases. We conclude that if financial and capital markets based on organic matter work efficiently, farmers will choose RMS in cotton production.residue management, organic matter, productivity, Crop Production/Industries,

FROM THE PERSPECTIVE OF GLOBAL WARMING: ALTERNATIVE FARMING SYSTEMS AND SUSTAINABILITY

According to Article 3.4 of the Kyoto Protocol, agricultural soil could be used as a sink for carbon sequestration. Soil sequestration of carbon provides dual benefits: an increase in soil productivity and a reduction in atmospheric carbon concentration. The gain in soil productivity is a slow process and attaining a steady-state level of carbon in soil takes several years. A frequently encountered difficulty in this situation is how to discount the future benefit of carbon sequestration into a current term. We compared the net benefit of four alternative management systems using discount rates based on the sliding gamma distribution, market rate of investment, and the social rate of time preference. We also calculated the sustainability of these alternate management systems based on the profitability and productivity index and their capacity to maintain the natural capital in soil. The result indicated that a management system that combines no-till and an organic source of nutrients is the most attractive system based on carbon sequestration, total discounted net present value, and sustainability perspectives.carbon sequestration, conservation practices, strong and weak sustainability, discounting method, Environmental Economics and Policy, Production Economics,

DYNAMIC ANALYSIS OF A RESIDUE MANAGEMENT SYSTEM IN COTTON

Residue management system (RMS) offers increase productivity gain to farmers by increasing the organic matter. Farmers have failed to realize this gain and consequently have not adopted RMS in cotton cultivation. Benefit of adopting RMS system appears sooner than farmers would think.Environmental Economics and Policy, Productivity Analysis,

NUMERAIRE CHOICE IN AGRICULTURAL SUPPLY ANALYSIS

Economic theory provides little guidance for selecting a numeraire in estimating dual function profit functions. In this study, we examine the choice of numeraire price (equation) for profit function models of Iowa agriculture. The choice of numeraire is evaluated by forecasting accuracy and with a non-nested specification test.Research Methods/ Statistical Methods,