Photonic qubits, qutrits and ququads accurately prepared and delivered on demand

Reliable encoding of information in quantum systems is crucial to all approaches to quantum information processing or communication. This applies in particular to photons used in linear optics quantum computing (LOQC), which is scalable provided a deterministic single-photon emission and preparation is available. Here, we show that narrowband photons deterministically emitted from an atom-cavity system fulfill these requirements. Within their 500 ns coherence time, we demonstrate a subdivision into d time bins of various amplitudes and phases, which we use for encoding arbitrary qu-d-its. The latter is done deterministically with a fidelity >95% for qubits, verified using a newly developed time-resolved quantum-homodyne method.Comment: 5 pages, 4 figure

Four quadrant 120 A, 10 V power converters for LHC

The LHC (Large Hadron Collider) particle accelerator makes extensive use of true bipolar power converters, with a high precision regulated output current requirement. A special design and topology is required to allow high performance within the converter operating area, including quadrant transition. This paper presents the ±120A ±10V power converter, well represented in the LHC power converters (300 units). The design is adapted for a wide range of magnet loads [from 10mH to 4 Henry] (time constant load [0.1s..1050s]) with stringent EMC requirements. A quick-connect system was applied to the converter modules allowing easy installation and maintenance operations. Discussion of 4 quadrant control and practical results are presented

Investigating the intrinsic noise limit of Dayem bridge NanoSQUIDs

NanoSQUIDs made from Nb thin films have been produced with nanometre loop sizes down to 200 nm, using weak-link junctions with dimensions less than 60 nm. These composite (W/Nb) single layer thin film devices, patterned by FIB milling, show extremely good low-noise performance ∼170 nΦ0 at temperatures between 5 and 8.5 K and can operate in rather high magnetic fields (at least up to 1 T). The devices produced so far have a limited operating temperature range, typically only 1–2 K. We have the goal of achieving operation at 4.2 K, to be compatible with the best SQUID series array (SSA) preamplifier available. Using the SSA to readout the nanoSQUIDs provides us with a means of investigating the intrinsic noise of the former. In this paper we report improved white noise levels of these nanoSQUIDs, enabling potential detection of a single electronic spin flip in a 1-Hz bandwidth. At low frequencies the noise performance is already limited by SSA preamplifier noise

In silico analysis of expressed sequence tags from Trichostrongylus vitrinus (Nematoda): comparison of the automated ESTExplorer workflow platform with conventional database searches

<p>Abstract</p> <p>Background</p> <p>The analysis of expressed sequence tags (EST) offers a rapid and cost effective approach to elucidate the transcriptome of an organism, but requires several computational methods for assembly and annotation. Researchers frequently analyse each step manually, which is laborious and time consuming. We have recently developed ESTExplorer, a semi-automated computational workflow system, in order to achieve the rapid analysis of EST datasets. In this study, we evaluated EST data analysis for the parasitic nematode <it>Trichostrongylus vitrinus </it>(order Strongylida) using ESTExplorer, compared with database matching alone.</p> <p>Results</p> <p>We functionally annotated 1776 ESTs obtained <it>via </it>suppressive-subtractive hybridisation from <it>T. vitrinus</it>, an important parasitic trichostrongylid of small ruminants. Cluster and comparative genomic analyses of the transcripts using ESTExplorer indicated that 290 (41%) sequences had homologues in <it>Caenorhabditis elegans</it>, 329 (42%) in parasitic nematodes, 202 (28%) in organisms other than nematodes, and 218 (31%) had no significant match to any sequence in the current databases. Of the <it>C. elegans </it>homologues, 90 were associated with 'non-wildtype' double-stranded RNA interference (RNAi) phenotypes, including embryonic lethality, maternal sterility, sterile progeny, larval arrest and slow growth. We could functionally classify 267 (38%) sequences using the Gene Ontologies (GO) and establish pathway associations for 230 (33%) sequences using the Kyoto Encyclopedia of Genes and Genomes (KEGG). Further examination of this EST dataset revealed a number of signalling molecules, proteases, protease inhibitors, enzymes, ion channels and immune-related genes. In addition, we identified 40 putative secreted proteins that could represent potential candidates for developing novel anthelmintics or vaccines. We further compared the automated EST sequence annotations, using ESTExplorer, with database search results for individual <it>T. vitrinus </it>ESTs. ESTExplorer reliably and rapidly annotated 301 ESTs, with pathway and GO information, eliminating 60 low quality hits from database searches.</p> <p>Conclusion</p> <p>We evaluated the efficacy of ESTExplorer in analysing EST data, and demonstrate that computational tools can be used to accelerate the process of gene discovery in EST sequencing projects. The present study has elucidated sets of relatively conserved and potentially novel genes for biological investigation, and the annotated EST set provides further insight into the molecular biology of <it>T. vitrinus</it>, towards the identification of novel drug targets.</p

Innate Immune Response Induced in Gnotobiotic Piglets by a Mixed Culture of Commensal Bacteria

Our laboratory has developed a recombined porcine-derived mixed bacterial culture (RPCF) isolated from the ceca of a healthy, pathogen-free pig and have maintained it at steady state in a continuous-flow chemostat. The culture has been shown to protect neonatal and weaned pigs from infection and disease caused by Salmonella and E. coli. However, the mechanism of action of the protection from pathogens observed with the RPCF culture remains unclear

Dynamic Energy Budget models: fertile ground for understanding resource allocation in plants in a changing world

Climate change is having dramatic effects on the diversity and distribution of species. Many of these effects are mediated by how an organism’s physiological patterns of resource allocation translate into fitness through effects on growth, survival and reproduction. Empirically, resource allocation is challenging to measure directly and so has often been approached using mathematical models, such as Dynamic Energy Budget (DEB) models. The fact that all plants require a very similar set of exogenous resources, namely light, water and nutrients, integrates well with the DEB framework in which a small number of variables and processes linked through pathways represent an organism’s state as it changes through time. Most DEB theory has been developed in reference to animals and microorganisms. However, terrestrial vascular plants differ from these organisms in fundamental ways that make resource allocation, and the trade-offs and feedbacks arising from it, particularly fundamental to their life histories, but also challenging to represent using existing DEB theory. Here, we describe key features of the anatomy, morphology, physiology, biochemistry, and ecology of terrestrial vascular plants that should be considered in the development of a generic DEB model for plants. We then describe possible approaches to doing so using existing DEB theory and point out features that may require significant development for DEB theory to accommodate them. We end by presenting a generic DEB model for plants that accounts for many of these key features and describing gaps that would need to be addressed for DEB theory to predict the responses of plants to climate change. DEB models offer a powerful and generalizable framework for modelling resource allocation in terrestrial vascular plants, and our review contributes a framework for expansion and development of DEB theory to address how plants respond to anthropogenic change

Studying patterns of use of transport modes through data mining - Application to U.S. national household travel survey data set

Data collection activities related to travel require large amounts of financial and human resources to be conducted successfully. When available resources are scarce, the information hidden in these data sets needs to be exploited, both to increase their added value and to gain support among decision makers not to discontinue such efforts. This study assessed the use of a data mining technique, association analysis, to understand better the patterns of mode use from the 2009 U.S. National Household Travel Survey. Only variables related to self-reported levels of use of the different transportation means are considered, along with those useful to the socioeconomic characterization of the respondents. Association rules potentially showed a substitution effect between cars and public transportation, in economic terms but such an effect was not observed between public transportation and nonmotorized modes (e.g., bicycling and walking). This effect was a policy-relevant finding, because transit marketing should be targeted to car drivers rather than to bikers or walkers for real improvement in the environmental performance of any transportation system. Given the competitive advantage of private modes extensively discussed in the literature, modal diversion from car to transit is seldom observed in practice. However, after such a factor was controlled, the results suggest that modal diversion should mainly occur from cars to transit rather than from nonmotorized modes to transi

Highly Efficient Source for Indistinguishable Photons of Controlled Shape

We demonstrate a straightforward implementation of a push-button like single-photon source which is based on a strongly coupled atom-cavity system. The device operates intermittently for periods of up to 100 microseconds, with single-photon repetition rates of 1.0 MHz and an efficiency of 60 %. Atoms are loaded into the cavity using an atomic fountain, with the upper turning point near the cavity's mode centre. This ensures long interaction times without any disturbances induced by trapping potentials. The latter is the key to reaching deterministic efficiencies as high as obtained in probabalistic photon-heralding schemes. The price to pay is the random loading of atoms into the cavity and the resulting intermittency. However, for all practical purposes, this has a negligible impact