Universal Dynamical Decoupling: Two-Qubit States and Beyond

Uhrig's dynamical decoupling pulse sequence has emerged as one universal and highly promising approach to decoherence suppression. So far both the theoretical and experimental studies have examined single-qubit decoherence only. This work extends Uhrig's universal dynamical decoupling from one-qubit to two-qubit systems and even to general multi-level quantum systems. In particular, we show that by designing appropriate control Hamiltonians for a two-qubit or a multi-level system, Uhrig's pulse sequence can also preserve a generalized quantum coherence measure to the order of $1+O(T^{N+1})$, with only $N$ pulses. Our results lead to a very useful scheme for efficiently locking two-qubit entangled states. Future important applications of Uhrig's pulse sequence in preserving the quantum coherence of multi-level quantum systems can also be anticipated.Comment: 10 pages, 4 figures, minor changes made, submitted to PR

Heat Conduction in two-dimensional harmonic crystal with disorder

We study the problem of heat conduction in a mass-disordered two-dimensional harmonic crystal. Using two different stochastic heat baths, we perform simulations to determine the system size (L) dependence of the heat current (J). For white noise heat baths we find that J ~ 1/L^a with $a \approx 0.59$ while correlated noise heat baths gives $a \approx 0.51$. A special case with correlated disorder is studied analytically and gives a=3/2 which agrees also with results from exact numerics.Comment: Revised version. 4 pages, 3 figure

Are Asians comfortable with discussing death in health valuation studies? A study in multi-ethnic Singapore

BACKGROUND To characterize ease in discussing death (EID) and its influence on health valuation in a multi-ethnic Asian population and to determine the acceptability of various descriptors of death and "pits"/"all-worst" in health valuation. METHODS In-depth interviews (English or mother-tongue) among adult Chinese, Malay and Indian Singaporeans selected to represent both genders and a wide range of ages/educational levels. Subjects rated using 0–10 visual analogue scales (VAS): (1) EID, (2) acceptability of 8 descriptors for death, and (3) appropriateness of "pits" and "all-worst" as descriptors for the worst possible health state. Subjects also valued 3 health states using VAS followed by time trade-off (TTO). The influence of sociocultural variables on EID and these descriptors was studied using univariable analyses and multiple linear regression (MLR). The influence of EID on VAS/TTO utilities with adjustment for sociocultural variables was assessed using MLR. RESULTS Subjects (n = 63, 35% Chinese, 32% Malay, median age 44 years) were generally comfortable with discussing death (median EID: 8.0). Only education significantly influenced EID (p = 0.045). EID correlated weakly with VAS/TTO scores (range: VAS: -0.23 to 0.07; TTO: -0.14 to 0.11). All subjects felt "passed away", "departed" and "deceased" were most acceptable (median acceptability: 8.0) while "sudden death" and "immediate death" were least acceptable (median acceptability: 5.0). Subjects clearly preferred "all-worst" to "pits" (63% vs. 19%, p < 0.001). CONCLUSION Singaporeans were generally comfortable with discussing death and had clear preferences for several descriptors of death and for "all-worst". EID is unlikely to influence health preference measurement in health valuation studies

Magnetic properties of exchange biased and of unbiased oxide/permalloy thin layers: a ferromagnetic resonance and Brillouin scattering study

Microstrip ferromagnetic resonance and Brillouin scattering are used to provide a comparative determination of the magnetic parameters of thin permalloy layers interfaced with a non-magnetic (Al2O3) or with an antiferromagnetic oxide (NiO). It is shown that the perpendicular anisotropy is monitored by an interfacial surface energy term which is practically independent of the nature of the interface. In the investigated interval of thicknesses (5-25 nm) the saturation magnetisation does not significantly differ from the reported one in bulk permalloy. In-plane uniaxial anisotropy and exchange-bias anisotropy are also derived from this study of the dynamic magnetic excitations and compared to our independent evaluations using conventional magnetometryComment: 7 pages, 6 figures, submited to Journal of Physics: Condensed Matte

The efficiency and effectiveness of a mixed public-private broadband deployment

Although it is widely accepted that the future telecommunications access infrastructure relies heavily on Fiber-to-the- Home (FTTH), its deployment is compromised because it requires substantial investment. As such, if the decision to go ahead with the investment is made, the partners involved should make sure the deployment and operations are performed as efficiently and effectively as possible, to ensure both economic and social viability. A deployment is efficient if achieved at minimum expense and is effective if it reaches the outlined goals. This paper analyses the impact of policy decisions affecting the efficiency and effectiveness of New Zealand's public-private partnership in charge of building up a nationwide FTTH network: the Ultra-Fast Broadband (UFB) network. The paper concludes that in the context of such type of partnership a trade-off exists between efficiency and effectiveness. Although both concepts are well suited for assessing the performance of large-scale projects such as FTTH rollouts, they are not necessarily always aligned

A supply chain vulnerability map for the automotive and electronic industries in Brazil / Mauricio F. Blos, Hui-Ming Wee

This paper aims to explore various perspectives of the Supply Chain Risk Management (SCRM) as they relate to the automotive and electronic industries in Brazil based on the historical data from 2010 to 2016. The methodological approach was based on the Supply Chain Vulnerability Map (SCVM). The SCVM was tested in its totaliness and two more risks were added to the hazard vulnerability category to form the SCVM II. The exploratory surveys were used to better understand the impacts on the automotive and electronic industries in Brazil during the study period. An interesting finding was that most of the major automotive and electronic industries are concerned with integrating risk management, governance and compliance in the supply chain. The findings of the empirical investigation and SCRM historical data indicate that managers must integrate risk management, governance and compliance in the supply chain and use the proposed SCVM II. This research revealed the risks that surrounded the supply chain during the time period covered. In the study, the researchers added two more risks to the hazard vulnerability category: item 10, deficient rainfall (as seen in Manaus and São Paulo) and number 13, viral epidemics (to reflect the Zika virus around Brazil), it was named as SCVMII. Among the limitations of the research was that the study applied real data which might vary drastically due to economic downturn of the country. This might affect the performance of the investigated industrie

Foreign exchange exposure: Evidence from the U.S. insurance industry

We study the foreign exchange exposure of U.S. insurers. The evidence shows that no systematic difference exists in the currency risk profiles of life and non-life segments within the insurance industry. This suggests that life and non-life insurers have similar risk exposure management strategies arising from similar risk pooling and financial intermediary functions. The empirical results reveal that a sizable proportion of U.S. insurers are exposed to foreign exchange movements against the seven largest U.S. trade partners in insurance services (U.K., Japan, Switzerland, Netherlands, France, Germany and Canada). Significant operational and size effects are also documented and we find that the frequency of foreign exchange exposure increases with time horizon

An optical study of interdiffusion in ZnSe/ZnCdSe

Copyright 1996 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. This article appeared in Applied Physics Letters 69, 1579 (1996) and may be found at