Suboptimal quantum-error-correcting procedure based on semidefinite programming

In this paper, we consider a simplified error-correcting problem: for a fixed encoding process, to find a cascade connected quantum channel such that the worst fidelity between the input and the output becomes maximum. With the use of the one-to-one parametrization of quantum channels, a procedure finding a suboptimal error-correcting channel based on a semidefinite programming is proposed. The effectiveness of our method is verified by an example of the bit-flip channel decoding.Comment: 6 pages, no figure, Some notations differ from those in the PRA versio

Dynamical model of financial markets: fluctuating `temperature' causes intermittent behavior of price changes

We present a model of financial markets originally proposed for a turbulent flow, as a dynamic basis of its intermittent behavior. Time evolution of the price change is assumed to be described by Brownian motion in a power-law potential, where the `temperature' fluctuates slowly. The model generally yields a fat-tailed distribution of the price change. Specifically a Tsallis distribution is obtained if the inverse temperature is $\chi^{2}$-distributed, which qualitatively agrees with intraday data of foreign exchange market. The so-called `volatility', a quantity indicating the risk or activity in financial markets, corresponds to the temperature of markets and its fluctuation leads to intermittency.Comment: 9 pages including 2 figure

Performance of fuel cell using calcium phosphate hydrogel membrane prepared from waste incineration fly ash and chicken bone powder

Waste incineration fly ash and bone powder could be Successfully recycled to calcium phosphate hydrogel, a type of fast proton conductor. The electric conductivity of the crystallized hydrogel from them was compared with that from calcium carbonate reagent. It was found that the conductivity of the hydrogel from bone powder is almost equal to that from Calcium carbonate reagent, which is higher than that from incineration fly ash. Because the crystallized hydrogel from incineration ash has a lower crystallinity than that from bone powder and calcium carbonate reagent. However, the difference of the conductivity among them can be hardly observed above 100 degrees C. The fuel cell with membrane electrode assembly (MEA) using the calcium phosphate hydrogel membrane prepared from incineration fly ash and bone powder was observed to generate electricity. The performance of fuel cells having the hydrogel membrane obtained from all raw materials increases with the cell temperature, and the fuel cell containing the hydrogel membrane from incineration fly ash has the highest dependence of the fuel cell performance. For this reason, the difference in the cell performance among them can be hardly observed above 120 degrees C. This tendency agrees with the change in the electric conductivity with the temperature. Further, the performance of all fuel cells with the hydrogel membrane is superior to that of the fuel cell with perfluorosulfonic polymer membrane at temperatures greater than approximately 85 degrees C

Synthesis of calcium phosphate hydrogel from waste incineration fly ash and its application to fuel cell

Waste incineration fly ash was successfully recycled to calcium phosphate hydrogel, a type of fast proton conductor. The crystallized hydrogel from incineration fly ash had a lower electric conductivity and a lower crystallinity than that from calcium carbonate reagent. However, the difference in electric conductivity between these crystallized hydrogels decreases with temperature. This was due to the presence of potassium in the incineration fly ash. The fuel cell with a membrane electrode assembly (MEA) using the calcium phosphate hydrogel membrane prepared from incineration fly ash was observed to generate electricity. The performance of this fuel cell was almost equal to that of a mixture of K2CO3 and CaCO3 reagents; further, the performance of the former was superior to the fuel cell with a perfluorosulfonic polymer membrane at temperatures greater than approximately 85 degrees C