Experimental distribution of entanglement with separable carriers

The key requirement for quantum networking is the distribution of entanglement between nodes. Surprisingly, entanglement can be generated across a network without direct transfer-or communication-of entanglement. In contrast to information gain, which cannot exceed the communicated information, the entanglement gain is bounded by the communicated quantum discord, a more general measure of quantum correlation that includes but is not limited to entanglement. Here, we experimentally entangle two communicating parties sharing three initially separable photonic qubits by exchange of a carrier photon that is unentangled with either party at all times. We show that distributing entanglement with separable carriers is resilient to noise and in some cases becomes the only way of distributing entanglement through noisy environments

Optimal imaging of remote bodies using quantum detectors

We implement a general imaging method by measuring the complex degree of coherence using linear optics and photon number resolving detectors. In the absence of collective or entanglement-assisted measurements, our method is optimal over a large range of practically relevant values of the complex degree of coherence. We measure the size and position of a small distant source of pseudothermal light, and show that our method outperforms the traditional imaging method by an order of magnitude in precision. Finally, we show that a lack of photon-number resolution in the detectors has only a modest detrimental effect on measurement precision and simulate imaging using the new and traditional methods with an array of detectors, showing that the new method improves both image clarity and contrast

willdenovii

Trifolium willdenovii Sprengeltrèfle de WilldenowTrifolium willdenovii2 miles NW of Kalama. Upper Kalama Roadopen slope with poison oa

multilobata

Packera multilobata  (Torr. & A. Gray ex A. Gray) W.A. Weber & A. LöveLobeleaf groundselWilliams Ski Area below Bill Williams MountainPonderosa oak forest7000 feetPonderosa, Oa

exaltatus

Senecio integerrimus Nuttallwestern ragwort;western groundsel;entire-leaved ragwort;entire-leaved groundsel;lamb's-tongue ragwortSenecio integerrimusMonitor PassDry part of meadow.7000 fee

Temporal and spatial prediction of radiocaesium transfer to food products

A recently developed semi-mechanistic temporal model to is used predict food product radiocaesium activity concentrations using soil characteristics available from spatial soil databases (exchangeable K, pH, % clay and % organic matter content). A raster database of soil characteristics, radiocaesium deposition, and crop production data has been developed for England and Wales and used to predict the spatial and temporal pattern of food product radiocaesium activity concentrations (Bq kg-1). By combining these predictions with spatial data for agricultural production, an area's output of radiocaesium can also be estimated, we term this flux (Bq y-1 unit area-1). Model predictions have been compared to observed data for radiocaesium contamination of cow milk in regions of England and Wales which received relatively high levels of fallout from the 1986 Chernobyl accident (Gwynedd and Cumbria). The model accounts for 56 and 80% of the observed variation in cow milk activity concentration for Gwynedd and Cumbria respectively. Illustrative spatial results are presented and suggest that in terms of food product contamination areas in the north and west of England and Wales are those most vulnerable to radiocaesium deposition. When vulnerability is assessed using flux the spatial pattern is more complex and depends upon food product

reventus

Astragalus reventus A. GrayBlue Mountain milkvetchKlickital C. Satus north of Satus Pass; Highway 8 about 20 miles easy of junction with 97steep bank about 700 feet above rock cres

Predicting the transfer of radiocaesium from organic soils to plants using soil characteristics

A model predicting plant uptake of radiocaesium based on soil characteristics is described. Three soil parameters required to determine radiocaesium bioavailability in soils are estimated in the model: the labile caesium distribution coefficient (kdl), K+ concentration in the soil solution [mK] and the soil solution→plant radiocaesium concentration factor (CF, Bq kg−1 plant/Bq dm−3). These were determined as functions of soil clay content, exchangeable K+ status, pH, NH+4 concentration and organic matter content. The effect of time on radiocaesium fixation was described using a previously published double exponential equation, modified for the effect of soil organic matter as a non-fixing adsorbent. The model was parameterised using radiocaesium uptake data from two pot trials conducted separately using ryegrass (Lolium perenne) on mineral soils and bent grass (Agrostis capillaris) on organic soils. This resulted in a significant fit to the observed transfer factor (TF, Bq kg−1 plant/Bq kg−1 whole soil) (P<0.001, n=58) and soil solution K+ concentration (mK, mol dm−3) (P<0.001, n=58). Without further parameterisation the model was tested against independent radiocaesium uptake data for barley (n=71) using a database of published and unpublished information covering contamination time periods of 1.2–10 years (transfer factors ranged from 0.001 to 0.1). The model accounted for 52% (n=71, P<0.001) of the observed variation in log transfer factor