2,572 research outputs found

    Extracting Information from Qubit-Environment Correlations

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    Most works on open quantum systems generally focus on the reduced physical system by tracing out the environment degrees of freedom. Here we show that the qubit distributions with the environment are essential for a thorough analysis, and demonstrate that the way that quantum correlations are distributed in a quantum register is constrained by the way in which each subsystem gets correlated with the environment. For a two-qubit system coupled to a common dissipative environment E\mathcal{E}, we show how to optimise interqubit correlations and entanglement via a quantification of the qubit-environment information flow, in a process that, perhaps surprisingly, does not rely on the knowledge of the state of the environment. To illustrate our findings, we consider an optically-driven bipartite interacting qubit ABAB system under the action of E\mathcal{E}. By tailoring the light-matter interaction, a relationship between the qubits early stage disentanglement and the qubit-environment entanglement distribution is found. We also show that, under suitable initial conditions, the qubits energy asymmetry allows the identification of physical scenarios whereby qubit-qubit entanglement minima coincide with the extrema of the AEA\mathcal{E} and BEB\mathcal{E} entanglement oscillations.Comment: 4 figures, 9 page

    Comparison of Standard Length, Fork Length, and Total Length for Measuring West Coast Marine Fishes

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    Measurements of adult marine fishes on the U.S. west coast are usually made using one of three methods: standard length, fork length, or total length. Each method has advantages and disadvantages. In this paper we attempt to determine whether one method is faster and/or more reliable than the other methods. We found that all three methods were comparable. There was no appreciable difference in the time it took to measure fish using the different methods. Fork length had the most reproducible results; however, it had the highest level of bias between researchers. We therefore suggest that selection of measurement type be based on what other researchers have used for the species under study. The best improvement in measurement reliability probably occurs by adequate training of personnel and not type of measurement used

    Scheme Independence of the Effective Hamiltonian for b→s γb \rightarrow s \, \gamma and b→s gb \rightarrow s \, g Decays

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    We present a calculation of the effective weak Hamiltonian which governs b→s γb \rightarrow s\, \gamma and b→s gb \rightarrow s \, g transitions in two different renormalization schemes (NDR and HV). In the leading logarithmic approximation, we show that the coefficients of the effective Hamiltonian are scheme independent only when one takes correctly into account the scheme dependence of one- and two- loop diagrams. We demonstrate that in NDR there are contributions which were missed in previous calculations. These contributions are necessary to obtain scheme independent coefficients in the final results.Comment: 16 pp + 5 figures not included (available by anonymous ftp at amisan.iss.infn.it (141.108.15.215), directory /ftp/bsgamma), LaTeX, LPTENS 93/28, ROME 93/958, ULB-TH 93/0

    Pueblo, comunidad y multicomunidad.

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    The Honorary White Population: Fighting for Self-Identification

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    The intent of this thesis is to explore the history of classification of Arab-Americans within the United States, showcase how Arab-Americans have encountered systematic racism, and give reasons why Arab-Americans should be able to self-identify. Currently, according to the Census definition, Middle Easterners fall under the White category. This is a misrepresentation of Middle Easterners as they should be considered a minority in light of societal treatment and policies set forth by policy makers. Even though much research has been conducted by the Census, they have elected to withhold the Middle Eastern or North African (MENA) category from the 2020 Census. Solutions for this issue are: Gaining universities\u27 involvement in the movement for a MENA category, encouraging legislation to place MENA as a minority within affirmative action, and the MENA category being placed on the 2030 census
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