Entangler and analyzer for multiphoton maximally entangled states using weak nonlinearities

In the regime of weak nonlinearity we present two general feasible schemes. One is an entangler for generating any one of the $n$-photon Greenberger-Horne-Zeilinge (GHZ) states and Bell states. After the interactions with cross-Kerr nonlinear media, a phase gate followed by a measurement on the probe beam, and appropriate local operations via classical feed-forward, one can obtain the desired states in a nearly deterministic way. Another scheme is an analyzer for multiphoton maximally entangled states, which is taken as a further application of the above entangler. In this scheme, all of the $2^n$ $n$-photon GHZ states can, nearly deterministically, be discriminated. Furthermore, an efficient two-step nondestructive Bell-state analyzer is designed.Comment: 7 pages, 6 figure

Gap Processing for Adaptive Maximal Poisson-Disk Sampling

In this paper, we study the generation of maximal Poisson-disk sets with varying radii. First, we present a geometric analysis of gaps in such disk sets. This analysis is the basis for maximal and adaptive sampling in Euclidean space and on manifolds. Second, we propose efficient algorithms and data structures to detect gaps and update gaps when disks are inserted, deleted, moved, or have their radius changed. We build on the concepts of the regular triangulation and the power diagram. Third, we will show how our analysis can make a contribution to the state-of-the-art in surface remeshing.Comment: 16 pages. ACM Transactions on Graphics, 201

Scheduled Delays? Scheduled Time Competition and On-Time Performance in the Airline Industry.

No abstractTime competition, on-time performance,

CARBON, TRADE POLICY, AND CARBON FREE TRADE AREAS

This paper discusses both the potential contribution that trade policy initiatives can make towards the achievement of significant global carbon emissions reduction and the potential impacts of proposals now circulating for carbon reduction motivated geographical trade arrangements, including carbon free trade areas. We first suggest that trade policy is likely to be a relatively minor consideration in climate change containment. The dominant influence on carbon emissions globally for next several decades will be growth more so than trade and its composition, and in turn, the size of trade seemingly matters more than its composition given differences in emission intensity between tradables and nontradables. We also note that differences in emissions intensity across countries are larger than across products or sectors and so issues of country discrimination in trade policy (and violations of MFN) arises. We next discuss both unilateral and regional carbon motivated trade policy arrangements, including three potential variants of carbon emission reduction based free trade area arrangements. One is regional trade agreements with varying types of trade preferences towards low carbon intensive products, low carbon new technologies and inputs to low carbon processes. A second is the use of joint border measures against third parties to counteract anti-competitive effects from groups of countries taking on deeper emission reduction commitments. A third is third country trade barriers along with free trade or other regional trade agreements as penalty mechanisms to pressure other countries to join emission reducing environmental agreements. We differentiate among the objectives, forms and possible impacts of each variant. We also speculate as to how the world trading system may evolve in the next few decades as trade policy potentially becomes increasingly dominated by environmental concerns. We suggest that the future evolution of the trading system will likely be with environmentally motivated arrangements acting as an overlay on prevailing trade and financial arrangements in the WTO and IMF, and eventually movement to linked global trade and environmental policy bargaining.carbon, trade policy, WTO, Regional Trade Agreements, trade barriers, anti-competitive effects

A Third Benefit of Joint Non-OPEC Carbon Taxes: Transferring OPEC Monopoly Rent

This paper highlights the potential for joint OECD (or non-OPEC) carbon taxes to reduce OPEC’s monopoly rent and provide benefit to non-OPEC countries provided jointly agreed trigger strategies are adhered to. In traditional economic theory, the primary purpose of a carbon tax is to internalize a global negative externality. A second benefit for individual countries is that the revenue raised by carbon tax can be used to reduce other tax rates and so lower the deadweight loss of tax system. In this paper, we discuss a third benefit of carbon taxes: transferring rents from OPEC to the oil importing countries.We develop a multi-region general equilibrium structure with endogenously determined oil supply for the purpose in which emissions are endogenously determined. We calibrate our model to 2006 data. Our analytics and numerical simulation results highlight how a uniform carbon tax used by all non-OPEC countries will increase the buyer’s price of oil but decrease the supplier’s price of oil, thus decreasing non-OPEC countries’ oil demand, and transferring OPEC monopoly rent to non-OPEC countries. Carbon taxes reduce the welfare of OPEC and increase the welfare of non-OPEC countries. Results also show how carbon taxes reduce global emissions, but the effect is small.carbon taxes, OECD, monopoly rent