A low-loss, broadband antenna for efficient photon collection from a coherent spin in diamond

We report the creation of a low-loss, broadband optical antenna giving highly directed output from a coherent single spin in the solid-state. The device, the first solid-state realization of a dielectric antenna, is engineered for individual nitrogen vacancy (NV) electronic spins in diamond. We demonstrate a directionality close to 10. The photonic structure preserves the high spin coherence of single crystal diamond (T2>100us). The single photon count rate approaches a MHz facilitating efficient spin readout. We thus demonstrate a key enabling technology for quantum applications such as high-sensitivity magnetometry and long-distance spin entanglement.Comment: 5 pages, 4 figures and supplementary information (5 pages, 8 figures). Comments welcome. Further information under http://www.quantum-sensing.physik.unibas.c

Characterization and tomography of a hidden qubit

In circuit-based quantum computing, the available gate set typically consists of single-qubit gates acting on each individual qubit and at least one entangling gate between pairs of qubits. In certain physical architectures, however, some qubits may be 'hidden' and lacking direct addressability through dedicated control and readout lines, for instance because of limited on-chip routing capabilities, or because the number of control lines becomes a limiting factor for many-qubit systems. In this case, no single-qubit operations can be applied to the hidden qubits and their state cannot be measured directly. Instead, they may be controlled and read out only via single-qubit operations on connected 'control' qubits and a suitable set of two-qubit gates. We first discuss the impact of such restricted control capabilities on the quantum volume of specific qubit coupling networks. We then experimentally demonstrate full control and measurement capabilities in a superconducting two-qubit device with local single-qubit control and iSWAP and controlled-phase two-qubit interactions enabled by a tunable coupler. We further introduce an iterative tune-up process required to completely characterize the gate set used for quantum process tomography and evaluate the resulting gate fidelities

Rarity of figs (Ficus) on Madagascar and its relationship to a depauperate frugivore community

Bien que plusieurs auteurs aient remarqué le faible nombre d'espèces frugivores présentes à Madagascar, l'interprétation de cette observation n'a jusqu'à présent fait l'objet que de quelques spéculations. Si l'on compare la forêt malgache à celles des régions tropicales de l'Ancien Monde, on y observe que le genre Ficus (généralement considéré comme une ressource-clé pour les frugivores des forêts tropicales) présente à la fois une faible diversité et une densité réduite. La productivité du groupe des Ficus y est relativement basse et sa phénologie ne correspond pas aux séquences habituellement observées par ailleurs. Ces facteurs - dont certains pourraient résulter de la longue période au cours de laquelle Madagascar a été isolée des blocs continentaux - sont considérés comme des paramètres importants pour expliquer le nombre réduit des frugivores sur cette île

Gastrointestinal parasite infection of the Gray mouse lemur (Microcebus murinus) in the littoral forest of Mandena, Madagascar: Effects of forest fragmentation and degradation

Faecal material from 169 individuals of Microcebus murinus living in five littoral forest fragments was analyzed for gastrointestinal parasites. The fragments differed in size and forest quality. Gastrointestinal parasite infection of M. murinus was characterised using parasite species richness, the prevalence of parasites, and the intensity of infection expressed as the number of parasite eggs, larvae and cysts per gram of faeces. For this, a modification of the McMaster flotation egg counting technique was applied to analyze egg shedding. We recorded nine gastrointestinal parasite species in faecal samples of Microcebus murinus. In good quality forest lemurs from a smaller fragment had higher prevalences and intensities of infection of gastrointestinal nematodes and protozoans than animals from a larger forest fragment. In large forests, excretion of eggs from Ascarididae and tapeworms was higher in a degraded forest fragment than in a good quality forest fragment. This situation was reversed in small forest fragments with fewer eggs of Suburula nematodes and protozoans shed by lemurs in the degraded fragment than by lemurs from the good quality fragment. Our analyses are hampered by the fact that we had only one forest fragment per type of treatment. Keeping this limitation in mind, the results are consistent with other studies and indicate that forest degradation and fragmentation have marked effects on the level of parasitism of Madagascar’s lemurs.RÉSUMÉDes matières fécales de 169 individus de Microcebus murinus vivant dans cinq fragments de forêt littorale du sud de Madagascar ont été analysées par la méthode modifiée de flottaison de McMaster. Ces animaux avaient été capturés entre avril 2003 et octobre 2005. Les fragments de forêt diffèrent entre eux par la taille et le degré de dégradation. Pour étudier l’impact de la fragmentation et de la dégradation de la forêt sur l’infestation parasitaire de cette espèce de lémurien, trois critères ont été évalués qui sont le nombre d’espèces de parasite, la prévalence et l’intensité de l’infestation. Les fragments ayant des tailles différentes mais montrant un même type de dégradation ont fait l’objet d’une comparaison au même titre que des fragments présentant un même degré de dégradation mais de mêmes tailles. Neuf espèces de parasites gastro-intestinaux ont été recensées chez Microcebus murinus de la forêt de Mandena dont six nématodes avec une espèce non-identifiée de la famille des Ascarididae et de l’ordre des Strongylida, Trichuris sp., deux espèces d’Oxyuridae dont l’une est du genre Lemuricola et une autre qui n’est pas encore identifiée, Subulura sp., deux cestodes appartenant au genre Hymenolepis et un protozoaire de l’ordre des Coccidia. La fragmentation et la dégradation de la forêt de Mandena affectent le parasitisme de cette espèce de lémurien. Les deux tendances qui ressortent de cette étude sont, d’une part, une augmentation de l’intensité et de la prévalence des parasites gastro-intestinaux de Microcebus murinus dans les plus petits fragments forestiers et d’autre part, une augmentation qui semble être en relation avec le degré de dégradation de la forêt dans les plus grands fragments. L’augmentation du nombre d’espèces de parasites avec la taille des fragments peut être une conséquence de la taille des fragments ou du nombre d’animaux échantillonnés. Dans les grands fragments, les microcèbes sont plus souvent infestés par les deux espèces de cestode lorsqu’ils sont dans des forêts dégradées que dans les fragments plus ou moins intacts. Dans les plus grandes parcelles forestières, la prévalence et l’intensité de l’infestation parasitaire sont plus élevées chez les microcèbes vivant dans les fragments très dégradés. Ce fait pourrait être dû à la réduction ou la perte de l’habitat associée à l’organisation sociale de l’animal car M. murinus dort en groupe pendant le jour, de sorte qu’une réduction de son habitat pourrait favoriser une augmentation des contacts interindividuels et la transmission de parasites, bien que l’infestation des microcèbes n’était pas liée à la densité des hôtes d’une manière significative. En connaissant l’effet néfaste des parasites, cette étude contribuerait à l’amélioration de la conservation de la biodiversité en relation avec les risques et les bénéfices des activités d’exploitation et de gestion de l’écosystème

Plant secondary metabolites and primate food choices : a meta-analysis and future directions

The role of plant secondary metabolites (PSMs) in shaping the feeding decisions, habitat suitability, and reproductive success of herbivorous mammals has been a major theme in ecology for decades. Although primatologists were among the first to test these ideas, studies of PSMs in the feeding ecology of non-human primates have lagged in recent years, leading to a recent call for primatologists to reconnect with phytochemists to advance our understanding of the primate nutrition. To further this case, we present a formal meta-analysis of diet choice in response to PSMs based on field studies on wild primates. Our analysis of 155 measurements of primate feeding response to PSMs is drawn from 53 studies across 43 primate species which focussed primarily on the effect of three classes of PSMs tannins, phenolics, and alkaloids. We found a small but significant effect of PSMs on the diet choice of wild primates, which was largely driven by the finding that colobine primates showed a moderate aversion to condensed tannins. Conversely, there was no evidence that PSMs had a significant deterrent effect on food choices of non-colobine primates when all were combined into a single group. Furthermore, within the colobine primates, no other PSMs influenced feeding choices and we found no evidence that foregut anatomy significantly affected food choice with respect to PSMs. We suggest that methodological improvements related to experimental approaches and the adoption of new techniques including metabolomics are needed to advance our understanding of primate diet choice

Predator avoidance and dietary fibre predict diurnality in the cathemeral folivore Hapalemur meridionalis

Though numerous mammalian taxa exhibit cathemerality (i.e. activity distributed across the 24-h cycle), this includes very few primates, exceptions being species from Aotinae and Lemuridae. Four non-mutually exclusive hypotheses have been proposed to explain the ultimate determinants for cathemeral activity in lemurs: thermoregulatory benefits, anti-predator strategy, competition avoidance and metabolic dietary-related needs. However, these have only been explored in the frugivorous genus Eulemur, with some species increasing nocturnality as a possible response to avoid diurnal raptors and to increase their ability to digest fibre during resource-scarce periods. Since Eulemur lack specializations for digesting bulk food, this strategy would allow for processing fibres over the full 24-h. The folivorous lemurids, i.e. genus Hapalemur, provide a divergent model to explore these hypotheses due to gastrointestinal adaptations for digesting dietary fibre and small body size compared to Eulemur. We linked continuous activity data collected from archival tags with observational behaviour and feeding data from three groups of adult Hapalemur meridionalis from January to December 2013. We tested the effects of thermoregulation, predator avoidance and the weighted proportion of digestible dietary fibre on the daily diurnal/nocturnal activity ratio using a Linear Mixed-Model. Our best-fit model revealed that increased canopy exposure and dietary fibre predicted greater diurnality. Our findings partly contrast with previous predictions for frugivorous lemurids. We propose a divergent adaptive explanation for folivorous lemurids. We suggest that the need to avoid terrestrial predators, as well as longer digestive bouts during bulk food periods, may override cathemerality in favour of diurnality in these bamboo lemurs

Small-scale coexistence of two mouse lemur species (Microcebus berthae and M. murinus) within a homogeneous competitive environment

Understanding the co-occurrence of ecologically similar species remains a puzzling issue in community ecology. The species-rich mouse lemurs (Microcebus spec.) are distributed over nearly all remaining forest areas of Madagascar with a high variability in species distribution patterns. Locally, many congeneric species pairs seem to co-occur, but only little detailed information on spatial patterns is available. Here, we present the results of an intensive capture–mark–recapture study of sympatric Microcebus berthae and M. murinus populations that revealed small-scale mutual spatial exclusion. Nearest neighbour analysis indicated a spatial aggregation in Microcebus murinus but not in M. berthae. Although the diet of both species differed in proportions of food categories, they used the same food sources and had high feeding niche overlap. Also, forest structure related to the spatial distribution of main food sources did not explain spatial segregation because parts used by each species exclusively did not differ in density of trees, dead wood and lianas. We propose that life history trade-offs that result in species aggregation and a relative increase in the strength of intra-specific over inter-specific competition best explain the observed pattern of co-occurrence of ecologically similar congeneric Microcebus species