A folded-sandwich polarization-entangled two-color photon pair source with large tuning capability for applications in hybrid quantum architectures

We demonstrate a two-color entangled pho ton pair source which can be adapted easily to a wide range of wavelengths combinations. A Fresnel rhomb as a geometrical quarter-wave plate and a versatile combination of compensation crystals are key components of the source. Entanglement of two photons at the Cs D1 line (894.3 nm) and at the telecom O-band (1313.1 nm) with a fidelity of $F = 0.753 \pm 0.021$ is demonstrated and improvements of the setup are discussed

Historical aspects of meetings, publication series, and digital resources dedicated to echinoderms

Half a century after the first scientific meeting dedicated to marine spiny-skinned animals (Deuterostomia: Echinodermata) was held in Washington, DC, we take this opportunity to provide information on a number of historical aspects related to the echinoderm scientific community. Apart from shedding light on the historical origins of modern echinoderm conferences, the present contribution presents photographs taken during the first meeting of echinoderm researchers in 1963 as well as during the first installments of the International Echinoderm Conference and the European Conference on Echinoderms. Furthermore, we provide background information on publication series dedicated solely to the Echinodermata as well as descriptions of selected digital resources that focus on echinoderms. Finally, we present a number of echinoderm conference logos and flyers in addition to selected information about specific echinoderm meetings

A new late Cenozoic species of Abertella (Echinoidea: Clypeasteroida) from Patagonia

A new species of abertellid sand dollar, Abertella miskellyi n. sp., is described from the Miocene Camarones Formation of Patagonia, southern Argentina. The new taxon corroborates the existence of the genus in South America, given that Abertella is most common in the southeastern USA and the eastern coast of Central America. It is characterized by a unique basicoronal circle, in which the interambulacral basicoronal plates are very heterogeneous in size (small in interambulacrum 5, largest in interambulacra 2 and 3). Additionally, it features disjunct oral interambulacra involving two ambulacral plates in some of the interambulacra rather than one, thus being the most disjunct of all known species of Abertella. A key to the species of the genus is provided.Fil: Kroh, Andreas. Naturhistorisches Museum Wien; AustriaFil: Mooi, Rich. California Academy of Sciences. Department of Invertebrate Zoology and Geology; Estados UnidosFil: del Rio, Claudia Julia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales; ArgentinaFil: Neumann, Christian. Museum für Naturkunde. Leibniz Institute for Research on Evolution and Biodiversity; Alemani

Evolution, turnovers and spatial variation of the gastropod fauna of the late Miocene biodiversity hotspot Lake Pannon

AbstractLake Pannon constituted the biggest hotspot of biodiversity in the late Cenozoic of Europe, comprising a total diversity of almost 600 gastropod species. The gastropod fauna of this huge brackish system, which existed over about seven million years from the late Miocene to earliest Pliocene within the Pannonian Basin System, has been well documented by a great many of taxonomic works. In contrast, the faunal development within the lake has not been properly addressed from a statistical point of view. The present investigation demonstrates that species were not homogeneously distributed across space and time, generating uneven and temporally shifting patterns of species richness and degree of point endemism across the lake. The faunal compositions of the time intervals analyzed were highly different, contrasting simple species accumulation as suggested by the overall numbers. Shifting patterns of local diversity within the lake reflect changing paleo-shorelines, resulting from prograding river systems entering and successively diminishing the lake surface area. As mainly herbivorous grazers and predominantly shallow-water inhabitants, the gastropods traced the moving shelf margins and vegetation belts accordingly, producing the observed diversity shifts. In addition, each time interval is characterized by a high degree of provincialism, which is considered to reflect high habitat diversity. This claim is supported by the complex subaqueous topography and the presence of extensive delta plains produced by the incoming river systems. A potential driver for provincialism might be the adaptation of species to distinct water depths (and related parameters). Finally, the notable differences among the faunal compositions of the upper Pannonian strata and the succeeding lower Viviparus beds, especially regarding family-level, indicate an environmental turnover at the transition. Brackish-water species are mostly replaced by typical freshwater elements, indicating strong fluvial influence. Based on our results and latest stratigraphic data, we conclude that the Viviparus beds were deposited in a different environment, replacing Lake Pannon in the southern Pannonian Basin in the early Pliocene

The marine fossils from Santa Maria Island. An Historical overview

In the Azores, Santa Maria is the only island with a sedimentary cover in a nine island volcanic system. This southeast most island of the archipelago has a rich fossil record, dated to the Late Miocene-Early Pliocene and to the Pleistocene. Palaeontological investigations on the island started in the late nineteen century. Nevertheless, through the next 150 years, the number of publications and thus the attention given to the fossil record of Santa Maria shows considerable fluctuation over time. From the beginning, the Miocene-Pliocene outcrops, more numerous in the island, focused the attention of the scholars. Recently, however, the interest has shifted to the Pleistocene outcrops. Data obtained from these outcrops has been used extensively in the interpretation and discussion of the Azorean geological genesis and evolution, particularly of Santa Maria, the oldest island of the archipelago. However, its role in the interpretation and discussion of the origin and subsequent evolution of insular marine communities has been meagre. The checklists produced for Santa Maria’s fossiliferous outcrops, account for a large spectrum of represented animal groups. Workers have focused their attention on the molluscs, being the group best represented in the fossil record. Data on other animal groups is still scarce, particularly in case of the Pleistocene outcrops. The fossiliferous beds of Santa Maria are far from being an exhausted matter and further research in the Island should be considered

Sustainable Biodiversity Databasing: International, Collaborative, Dynamic, Centralised

The World Register of Marine Species (WoRMS) is a sustainable model of international collaboration around a centralised database that provides expert validated biodiversity data freely online. This model could be replicated for the over 1.2 million terrestrial and freshwater species to improve quality control and data management in biology and ecology globally

An efficient, tunable, and robust source of narrow-band photon pairs at the 87^{87}Rb D1 line

We present an efficient and robust source of photons at the $^{87}$Rb D1-line (795 nm) with a narrow bandwidth of $\delta=226(1)$ MHz. The source is based on non-degenerate, cavity-enhanced spontaneous parametric down-conversion in a monolithic optical parametric oscillator far below threshold. The setup allows for efficient coupling to single mode fibers. A heralding efficiency of $\eta_{\mathrm{heralded}}=45(5)$ % is achieved, and the uncorrected number of detected photon pairs is $3.8 \times 10^{3}/(\textrm{s mW})$. For pair generation rates up to $5\times 10^{5}/$s, the source emits heralded single photons with a normalized, heralded, second-order correlation function $g^{(2)}_{c}<0.01$. The source is intrinsically stable due to the monolithic configuration. Frequency drifts are on the order of $\delta/20$ per hour without active feedback on the emission frequency. We achieved fine-tuning of the source frequency within a range of $> 2$ GHz by applying mechanical strain.Comment: 6 pages, 4 figure

Методика использования виртуальной среды SolidWorks Simulation для формирования компетенций будущих инженеров

Формирование способности ассоциировать напряженно-деформированное состояние конструкций и моделей С