Quantum gates via relativistic remote control

We harness general relativistic effects to gain quantum control on a stationary qubit in an optical cavity by controlling the non-inertial motion of a different probe atom. Furthermore, we show that by considering relativistic trajectories of the probe, we enhance the efficiency of the quantum control. We explore the possible use of these relativistic techniques to build universal quantum gates.Comment: 4 pages (+ 4 pages Appendix). 4 figures. RevTex 4.

Multi-scale processes in metapopulations : Contributions of stage structure, rescue effect, and correlated extinctions

Peer reviewedPublisher PD

Test for a large amount of entanglement, using few measurements

Bell-inequality violations establish that two systems share some quantum entanglement. We give a simple test to certify that two systems share an asymptotically large amount of entanglement, n EPR states. The test is efficient: unlike earlier tests that play many games, in sequence or in parallel, our test requires only one or two CHSH games. One system is directed to play a CHSH game on a random specified qubit i, and the other is told to play games on qubits {i,j}, without knowing which index is i. The test is robust: a success probability within delta of optimal guarantees distance O(n^{5/2} sqrt{delta}) from n EPR states. However, the test does not tolerate constant delta; it breaks down for delta = Omega~(1/sqrt{n}). We give an adversarial strategy that succeeds within delta of the optimum probability using only O~(delta^{-2}) EPR states.Comment: 17 pages, 2 figures. Journal versio

Great Mining Camps of Canada 3. The History and Geology of the Cariboo Goldfield, Barkerville and Wells, BC

The discovery of placer gold deposits in the Cariboo in 1860, and the immediate realization of their importance, were directly responsible for the establishment of the Province of British Columbia, allowing Canada to expand from ‘Sea to Shining Sea.’ Later, in the early 1930s, the new lode gold mines helped rescue the province from bankruptcy during the Great Depression. The Cariboo Goldfield is one of the longest continuously productive mining camps in Canada (nearly 150 years). The Cariboo Goldfield, like the California Goldfield, manifests two styles of mineralization: 1) primary lode gold deposits, and 2) secondary placer deposits. In plan, the zone of lode deposits trends linearly about 6 km in a northwest–southeast direction, within an inverted boot-shaped cluster of placer deposits having a surface area of about 250 km2. Three zones of rich placer creeks also trend northwest– southeast within the goldfield, the most northeasterly of which envelopes the known lode trend. The Cariboo Goldfield encompasses two dominant rock domains–an upper or hanging-wall domain of late Paleozoic ophiolitic rocks, part of Slide Mountain Terrane, and a more widespread, lower or foot-wall domain of late Proterozoic to Paleozoic continental margin meta-sedimentary rocks, part of the Barkerville Terrane. In cross-section, the lode deposits are located in a sub-horizontal, terrane-bounding fault (suture or high-strain zone), which separates the hanging-wall and footwall domains. The vertical extent of the mineralized zone below this suture is half a kilo-metre or less. Gold occurs in both pyritic quartz veins and pyritic replacement deposits; the mineralogy of the ore is simple: gold-bearing (auriferous) pyrite and minor amounts of other sulfide minerals. Three lode mines in the goldfield are from southeast to northwest, the Cariboo Gold Quartz, Island Mountain and Mosquito Creek mines. Combined production from these mines between 1933 and 1987 is about 38.3 million grams (g) (1.23 million troy ounces) of gold and 3.16 million g (101 439 troy ounces) of silver, which would be worth more than one billion dollars at current prices (~US$900 gold). Major placer deposits are located largely along creeks in the Goldfield mostly lying in gutters on bedrock overlain by Late Tertiary gravels but gold is also redistributed within overlying glacial sediments. Gold nuggets exhibit diverse shapes, from irregular and drusy to rounded and hammered, indicative of varied histories of transport. Average fineness ranges from 830 to 950 [gold to gold+silver, pure gold = 1000]. Since 1860, placer mines probably produced more than 118.2 million g (3.8 million troy ounces) worth about 3.4 billion dollars at current prices. Adventuresome placer miners reached the south end of the Goldfield in the winter of 1860 and the major producing creeks were all discovered during the following year. Initial mining took place in shallow deposits along creeks but within a year some mining was underway in water saturated gravels to depths of 20 m. Production peaked in 1863 but has continued at diminished rates until today. As placer production tailed off, great efforts went into the search for lode deposits. Many mineralized, pyritic quartz veins were found with very fine-grained gold contained within pyrite, but quartz veins containing nugget gold typical of that found in the placers remained elusive. In spite of provincial government assistance by providing milling and roasting facilities to process the lode deposits, the technology of the day was inadequate to make the deposits economic. The lodes were not viable until cyanide treatment became available and the price of gold rose. The Cariboo Gold Quartz mine opened in January 1933 and Island Mountain in November 1934. The Cariboo Gold Quartz purchased the Island Mountain mine in 1959 and both mines continued producing until 1967 when they closed because of unfavourable economics. Higher gold prices resulted in the Mosquito Creek mine coming into production in 1980 and continuing until 1987, after prices had receded. Recent high gold prices have again stimulated significant exploration. Like all gold rushes, the Cariboo has had a cast of strong and interesting characters. Four of the most memorable include: Billy Barker, an early placer miner; Bill Hong, a later Chinese placer miner; Amos Bowman, the first geologist; and Fred Wells, a prospector and mining entrepreneur during the heyday of lode mining. The village of Barkerville, named after Billy Barker, is now the site of a provincial park and museum dedicated to the gold rush, and the nearby town of Wells, named after Fred Wells, now functions mainly as a base for seasonal tourism, some exploration, and minor placer mining. RÉSUMÉ La découverte des gisements aurifères dans la région de Cariboo en 1860, et la prise de conscience immédiate de leur importance, sont les causes directes de la création de la province de Colombie-Britannique, ce qui a permis au Canada de s’étendre « d’un océan à l’autre ». Puis, au début des années 1930, de nouvelles mines d’or filonien ont permis de sauver la province de la faillite durant la Grande crise. Le champ aurifère de Cariboo est l’un des camps miniers ayant été en production continue le plus longtemps au Canada (presque 150 ans). Le champ aurifère de Cariboo, comme le champ aurifère de Californie, comporte deux styles de minéralisation : 1) des gisements primaires d’or filoniens, et 2) des gisements secondaires placériens. En plan, la zone de gisements filoniens s’étire sur 6 km du nord-ouest vers le sud-est, au sein d’un essain de gisements placériens formant une botte inversée d’une superficie de 250 km2. Trois zones de ruisseaux de riches gisements d’or placériens s’étirent aussi du nordouest au sud-est au sein de la région aurifère, la plus au nord-est envelop-pant la zone de gisements filoniens. Le champ aurifère de Cariboo comprend deux domaines principaux de roches – à l’éponte supérieure, un domaine de roches ophiolitiques paléozoïques faisant partie du terrane de Slide Mountain, et à l’éponte inférieure, un domaine plus étendu de roches métasédimentaires de marge continentale de la fin du Protérozoïque et du Paléozoïque faisant partie du terrane de Barkerville. En coupe, on peut voir que les gisements filoniens sont situés dans la zone d’une faille subhorizontale (de suture ou de déformation intense) séparant les domaines des deux épontes. Verticalement, l’épaisseur de la zone minéralisée sous cette suture ne dépasse pas un demi kilomètre. L’or se présente tantôt dans des veines de quartz pyritiques et tantôt dans des gisements de remplacement pyritique; la minéralogie du minerai est simple : il s’agit de pyrite aurifère et de quantités mineures d’autres minéraux sulfurés. Dans le champ minier, du sudest vers le nord-ouest on trouve trois mines d’or filonien, soit les mines Cariboo Gold Quartz, Island Mountain et Mosquito Creek. La production combinée de ces trois mines entre 1933 et 1987 totalise environ 38,3 millions de grammes (1,23 onces troy) d’or et 3,16 millions de grammes (101 439 onces troy) d’argent, ce qui vaudrait plus d’un milliard de dollars au prix actuels (~900$ US l’once d’or). Les gisements placériens les plus importants sont situés surtout le long de ruisseaux du champ minier formant gouttière sur le substratum recouverts de graviers de la fin du Tertiaire, mais on trouve aussi de l’or remobilisé au sein des dépôts glaciaires sus-jacents. Les pépites d’or se présentent sous des formes diverses, allant d’irrégulières et drusiques à arrondies et martelées, selon l’historique de leur transport. En moyenne la pureté (titre) varie de 830 à 950 (or à or + argent, or pure=1000). Depuis 1860, les mines placériennes ont donné plus de 118,2 millions de grammes (3,8 millions d’onces troy), ce qui vaut environ 3,4 milliards de dollars aux prix actuels. Les chercheurs d’or les plus aventureux ont atteint la limite sud du champ minier à l’hiver de 1860, et les principaux ruisseaux producteurs ont tous été découverts durant l’année suivante. Au début, l’extraction s’est faite à partir des gisements peu pro-fonds le long des ruisseaux, mais en moins d’une année on a travaillé à partir de gisements de graviers saturés d’eau à des profondeurs de 20 m. La meilleur année de production a été 1863, mais la production s’est poursuivie jusqu’à maintenant à des rythmes moindres. Au fur et à mesure que la production placérienne baissait, on a investit de plus en plus d’efforts d’exploration en quête de gisements filoniens. On a trouvé de nombreux gisements filoniens de quarts minéralisés de pyrite renfermant des grains d’or très fins, sans que l’on puisse trouver des gisements filoniens de quartz renfermant des pépites d’or comme celles des gisements d’or placériens. En dépit de l’aide gouvernemental provinciale qui a fourni des installations de concassage et de grillage du minerai filonien, la technologie d’alors n’en permettait pas une exploitation profitable. L’exploitation des gisements filoniens sont demeurés non rentables jusqu’à l’avènement du traitement par cyanure et la hausse du prix. La mine Cariboo Gold Quartz a été inaugurée en janvier 1933 et la mine Island Mountain en novembre 1934. La mine Cariboo Gold Quartz a acheté la mine Island Mountain en 1959 et les deux exploitations ont continué leurs opérations jusqu’à leur fermeture en 1967 à cause d’un contexte économique défavorable. De meilleurs prix pour l’or ont permis l’ouverture de la mine Mosquito Creek en 1980, opérations qui ont continuées jusqu’en 1987, jusqu’à une baisse insoutenable du prix de l’or. La remontée récente des prix a encore une fois stimulé des investissements significatifs en exploration. Comme toutes les ruées vers l’or, celle de la région de Cariboo a eu ses personnages intéressants. En voici quatre parmi les plus illustres : Billy Parker, un des premiers mineurs; Bill Hong, un mineur placérien arrivé plus tard; Amos Bowman, le premier géologue; et Fred Wells, un prospecteur et entrepreneur minier de l’âge d’or de l’exploitation minière filonienne. Le village de Bakerville, du nom de Billy Barker, est maintenant le site d’un parc provincial et d’un musée dédié à la ruée vers l’or, et non loin de là, la petite ville de Wells, du nom de Fred Wells, doit son existence surtout au tourisme saisonnier, à l’exploration minérale et à quelques activités mineures d’extraction de placers

The value of considering demographic contributions to connectivity - a review

Connectivity is a central concept in ecology, wildlife management, and conservation science. Understanding the role of connectivity in determining species persistence is increasingly important in the face of escalating anthropogenic impacts on climate and habitat. These connectivity augmenting processes can severely impact species distributions and community and ecosystem functioning. One general definition of connectivity is that it is an emergent process arising from a set of spatial interdependencies between individuals or populations, and increasingly realistic representations of connectivity are being sought. Generally, connectivity consists of a structural component, relating to the distribution of suitable and unsuitable habitat, and a functional component, relating to movement behavior, yet the interaction of both components often better describes ecological processes. Additionally, although implied by ‘movement', demographic measures such as the occurrence or abundance of organisms are regularly overlooked when quantifying connectivity. Integrating such demographic contributions based on the knowledge of species distribution patterns is critical to understanding the dynamics of spatially structured populations. Demographically-informed connectivity draws from fundamental concepts in metapopulation ecology while maintaining important conceptual developments from landscape ecology, and the methodological development of spatially-explicit hierarchical statistical models that have the potential to overcome modeling and data challenges. Together, this offers a promising framework for developing ecologically realistic connectivity metrics. This review synthesizes existing approaches for quantifying connectivity and advocates for demographically-informed connectivity as a general framework for addressing current problems across ecological fields reliant on connectivity-driven processes such as population ecology, conservation biology and landscape ecology. Using supporting simulations to highlight the consequences of commonly made assumptions that overlook important demographic contributions, we show that even small amounts of demographic information can greatly improve model performance. Ultimately, we argue demographic measures are central to extending the concept of connectivity and resolves long-standing challenges associated with accurately quantifying the influence of connectivity on fundamental ecological processes.Publisher PDFPeer reviewe

The Value of Considering Demographic Contributions to Connectivity: A Review

Connectivity is a central concept in ecology, wildlife management, and conservation science. Understanding the role of connectivity in determining species persistence is increasingly important in the face of escalating anthropogenic impacts on climate and habitat. These connectivity augmenting processes can severely impact species distributions and community and ecosystem functioning. One general definition of connectivity is that it is an emergent process arising from a set of spatial interdependencies between individuals or populations, and increasingly realistic representations of connectivity are being sought. Generally, connectivity consists of a structural component, relating to the distribution of suitable and unsuitable habitat, and a functional component, relating to movement behavior, yet the interaction of both components often better describes ecological processes. Additionally, although implied by \u27movement\u27, demographic measures such as the occurrence or abundance of organisms are regularly overlooked when quantifying connectivity. Integrating such demographic contributions based on the knowledge of species distribution patterns is critical to understanding the dynamics of spatially structured populations. Demographically-informed connectivity draws from fundamental concepts in metapopulation ecology while maintaining important conceptual developments from landscape ecology, and the methodological development of spatially-explicit hierarchical statistical models that have the potential to overcome modeling and data challenges. Together, this offers a promising framework for developing ecologically realistic connectivity metrics. This review synthesizes existing approaches for quantifying connectivity and advocates for demographically-informed connectivity as a general framework for addressing current problems across ecological fields reliant on connectivity-driven processes such as population ecology, conservation biology and landscape ecology. Using supporting simulations to highlight the consequences of commonly made assumptions that overlook important demographic contributions, we show that even small amounts of demographic information can greatly improve model performance. Ultimately, we argue demographic measures are central to extending the concept of connectivity and resolves long-standing challenges associated with accurately quantifying the influence of connectivity on fundamental ecological processes

Visual Head Counts: A Promising Method for Efficient Monitoring of Diamondback Terrapins

Determining the population status of the diamondback terrapin (Malaclemys terrapin spp.) is challenging due to their ecology and limitations associated with traditional sampling methods. Visual counting of emergent heads offers a promising, efficient, and non-invasive method for generating abundance estimates of terrapin populations across broader spatial scales than has been achieved using capture–recapture, and can be used to quantify determinants of spatial variation in abundance. We conducted repeated visual head count surveys along the shoreline of Wellfleet Bay in Wellfleet, Massachusetts, and analyzed the count data using a hierarchical modeling framework designed specifically for repeated count data: the N-mixture model. This approach allows for simultaneous modeling of imperfect detection to generate estimates of true terrapin abundance. Detection probability was lowest when temperatures were coldest and when wind speed was highest. Local abundance was on average higher in sheltered sites compared to exposed sites and declined over the course of the sampling season. We demonstrate the utility of pairing visual head counts and N-mixture models as an efficient method for estimating terrapin abundance and show how the approach can be used to identifying environmental factors that influence detectability and distribution