Dynamic decoherence control of a solid-state nuclear-quadrupole qubit

We report on the application of a dynamic decoherence control pulse sequence on a nuclear-quadrupole transition in Pr3+∶Y2SiO5. Process tomography is used to analyze the effect of the pulse sequence. The pulse sequence was found to increase the decoherence time of the transition to over 30 seconds. Although the decoherence time was significantly increased, the population terms were found to rapidly decay on the application of the pulse sequence. The increase of this decay rate is attributed to inhomogeneity in the ensemble. Methods to circumvent this limit are discussed

Dynamic decoherence control of a solid-state nuclear quadrupole qubit

We report on the application of a dynamic decoherence control pulse sequence on a nuclear quadrupole transition in $Pr^{3+}:Y_2SiO_5$ . Process tomography is used to analyse the effect of the pulse sequence. The pulse sequence was found to increase the decoherence time of the transition to over 30 seconds. Although the decoherence time was significantly increased, the population terms were found to rapidly decay on the application of the pulse sequence. The increase of this decay rate is attributed to inhomogeneity in the ensemble. Methods to circumvent this limit are discussed.Comment: 4 pages, 6 figure

Method of extending hyperfine coherence times in Pr^3+:Y_2SiO_5

In this letter we present a method for increasing the coherence time of praseodymium hyperfine ground state transitions in Pr^3+:Y_2SiO_5 by the application of a specific external magnetic field. The magnitude and angle of the external field is applied such that the Zeeman splitting of a hyperfine transition is at a critical point in three dimensions, making the first order Zeeman shift vanishingly small for the transition. This reduces the influence of the magnetic interactions between the praseodymium ions and the spins in the host lattice on the transition frequency. Using this method a phase memory time of 82ms was observed, a value two orders of magnitude greater than previously reported. It is shown that the residual dephasing is amenable quantum error correction

Suitability of project M&E systems to support agricultural MRV: The case of the Kenya dairy NAMA

Several countries are developing nationally appropriate mitigation actions (NAMAs) in the livestock sector. Compared to research on emission factors, much less attention has been paid to understanding systems for collecting activity data on change in livestock management practices and animal performance. This paper presents a framework for synthetic assessment of MRV systems based on UNFCCC criteria for credible MRV. The framework is applied to case studies of two existing monitoring and evaluation systems in Kenya’s dairy sector to investigate the extent to which these systems could be used as the basis for collection and reporting of activity data for a dairy sector NAMA in Kenya. Analysis of the case studies highlights three main findings: (i) codifying data collection, management procedures and roles is important for increasing transparency, while quality control and quality assurance systems play key roles in increasing confidence in data quality; (ii) milk yield is a key indicator used in estimating GHG emissions in the dairy sector, but further research is needed on potential sources of uncertainty and bias associated with different data collection methods; (iii) the involvement of multiple institutions in implementation of the sector- wide NAMA raises challenges related to the consistency and comparability between data collected by different institutions. Options for improvement in MRV practices will be determined to a large extent by the requirements of data users. These issues are not unique to Kenya’s dairy NAMA. Further assessment of the quality of activity data and the characteristics of credible MRV systems will support practical improvements in MRV for agricultural mitigation actions

Review of life-cycle assessments of livestock production: Perspectives for application to environmental impact assessment in developing countries

This review draws on Life-Cycle Assessments (LCA) of livestock value chains. The current state of livestock LCAs is summarized, with an emphasis on limitations and lessons for a developing country context. Of the 149 LCAs reviewed, 19 incorporated developing countries. Key messages are: LCAs can be conducted for livestock value chains in developing countries; and, lessons can be learnt to improve the rigor of alternative methodologies including modeling, indicator specification, allocation of impact and incorporating sensitivity analysis. Further, results from existing LCAs provide a point of reference for future LCAs and sustainability assessments in developing countries