Demonstration of a Quantum Gate using Electromagnetically Induced Transparency

We demonstrate a native $\mathrm{CNOT}$ gate between two individually addressed neutral atoms based on electromagnetically induced transparency (EIT). This protocol utilizes the strong long-range interactions of Rydberg states to enable conditional state transfer on the target qubit when operated in the blockade regime. An advantage of this scheme is it enables implementation of multi-qubit CNOT$^k$ gates using a pulse sequence independent of qubit number, and provides an simple gate for efficient implementation of quantum algorithms and error correction. We achieve a loss corrected gate fidelity of $\mathcal{F}_\mathrm{CNOT}^\mathrm{cor} = 0.82(6)$, and prepare an entangled Bell-state with $\mathcal{F}_\mathrm{Bell}^\mathrm{cor} = 0.66(5)$, limited at present by laser power. We present a number of technical improvements to advance this to a level required for fault-tolerant scaling.Comment: 6 pages, 5 figures plus Supplementary Materia

Synthesis of Substituted Dihydrobenzofurans via Tandem S_NAr/5-Exo-Trig Cyclization

A tandem S_NAr/5-exo-trig cyclization reaction is reported that converts N-alkyl- and -arylimines derived from o-fluorobenzaldehydes into 3-amino-2,3-dihydro-2,2-diarylbenzofurans in moderate to good yields. Diarylmethoxide coupling partners serve the dual role of nucleophile in the S_NAr step and catalytic base in the cyclization step. With a subset of the substrates, a further base-induced elimination of the 3-amino-2,3-dihydro-2,2-diarylbenzofuran to a phenolic enamine was observed

Z-Selective Cross-Metathesis and Homodimerization of 3E-1,3-Dienes: Reaction Optimization, Computational Analysis, and Synthetic Applications

Olefin metathesis reactions with 3E-1,3-dienes using Z-selective cyclometalated ruthenium benzylidene catalysts are described. In particular, a procedure for employing 3E-1,3-dienes in Z-selective homodimerization and cross-metathesis with terminal alkenes is detailed. The reaction takes advantage of the pronounced chemoselectivity of a recently reported ruthenium-based catalyst containing a cyclometalated NHC ligand for terminal alkenes in the presence of internal E-alkenes. A wide array of commonly encountered functional groups can be tolerated, and only a small excess (1.5 equiv) of the diene coupling partner is required to achieve high yields of the desired internal E,Z-diene cross-metathesis product. Computational studies have been performed to elucidate the reaction mechanism. The computations are consistent with a diene-first pathway. The reaction can be used to quickly assemble structurally complex targets. The power of this cross-metathesis reaction is demonstrated by the concise syntheses of two insect pheromones

Reconnaissance Survey of the Irish Continental Shelf/Shelf Edge - Atlantic Irish Regional Survey (AIRS) 1996: A GLORIA Survey of the Irish Continental Margin

The Atlantic Irish Regional Survey (AIRS96) sidescan sonar survey was carried out in August 1996. Covering an area of 200,000 sq.km it represented the largest reconnaissance seabed survey of the Irish Continental Shelf region. It covered both margins, together with much of the basin floor, of the Irish sector of the Rockall Trough and extended into the northern part of the Porcupine Seabight. The objectives of this project were two fold: 1. Strategic: •to undertake, for the first time a preliminary reconnaissance survey of the Irish Continental Shelf/Shelf Edge, •to establish a strategic database on Shelf/Slope Edge conditions, •to provide training and experience to Irish researchers in state of the art marine surveying equipment (GLORIA) and data processing. 2. Scientific: •to document slope stability and mass wasting features on the margins of the Rockall Trough, •to map, where possible, occurrences of deep water carbonate mounds, •to investigate the sediment erosional, transport and depositional mechanisms that have shaped the present morphology of the region. The survey revealed a range of sedimentary features across the steep (i.e. >6º slope) margins and the basin floor in the Rockall Trough. Four classes of sedimentary feature are recognised: (1) mass failure, (2) canyon systems, (3) sediment fans, and (4) sediment drifts. The western margin is characterised by large-scale downslope mass movement features. The western and central parts of the basin floor in the Rockall Trough contain the Feni Sediment Ridge, a large Miocene-Recent contourite sediment accumulation draped by large sediment waves trending sub-parallel to the dominant modern current pattern. A large-scale downslope mass failure feature is recognised across 14,000 sq.km of the northeastern margin of the Rockall Trough. Smaller slides and slumps occur along the eastern margin in association with more prevalent canyon, channel and fan systems. A cluster of carbonate mounds was imaged in the northern part of the Porcupine Seabight. These represent part of one of the most extensive suites of deep-water carbonate mounds in the Atlantic Margin and are currently the subject of a number of new EU-funded research projects. Strong northward-directed bottom currents along the eastern margin are suggested to erode, circulate and re-deposit sediment on the basin floor and on the western margin of the Rockall Trough. The main terrigenous sedimentary input was from the Irish Mainland Shelf. A broad interplay of alongslope and downslope sediment transport processes shaped the morphology of the Rockall Trough, while tectonically-driven basin subsidence, Quaternary glaciations and glacio-eustatic sea-level fluctuations also influenced the overall sedimentation pattern in the Rockall Trough.Funder: Marine Institut

Origins of Initiation Rate Differences in Ruthenium Olefin Metathesis Catalysts Containing Chelating Benzylidenes

A series of second-generation ruthenium olefin metathesis catalysts was investigated using a combination of reaction kinetics, X-ray crystallography, NMR spectroscopy, and DFT calculations in order to determine the relationship between the structure of the chelating o-alkoxybenzylidene and the observed initiation rate. Included in this series were previously reported catalysts containing a variety of benzylidene modifications as well as four new catalysts containing cyclopropoxy, neopentyloxy, 1-adamantyloxy, and 2-adamantyloxy groups. The initiation rates of this series of catalysts were determined using a UV/vis assay. All four new catalysts were observed to be faster-initiating than the corresponding isopropoxy control, and the 2-adamantyloxy catalyst was found to be among the fastest-initiating Hoveyda-type catalysts reported to date. Analysis of the X-ray crystal structures and computed energy-minimized structures of these catalysts revealed no correlation between the Ru–O bond length and Ru–O bond strength. On the other hand, the initiation rate was found to correlate strongly with the computed Ru–O bond strength. This latter finding enables both the rationalization and prediction of catalyst initiation through the calculation of a single thermodynamic parameter in which no assumptions about the mechanism of the initiation step are made

An Initiation Kinetics Prediction Model Enables Rational Design of Ruthenium Olefin Metathesis Catalysts Bearing Modified Chelating Benzylidenes

Rational design of second-generation ruthenium olefin metathesis catalysts with desired initiation rates can be enabled by a computational model that is dependent on a single thermodynamic parameter. Using a computational model with no assumption about the specific initiation mechanism, the initiation kinetics of a spectrum of second-generation ruthenium olefin metathesis catalysts bearing modified chelating ortho-alkoxy benzylidenes were predicted in this work. Experimental tests of the validity of the computational model were achieved by the synthesis of a series of ruthenium olefin metathesis catalysts and investigation of initiation rates by ultraviolet–visible light (UV-vis) kinetics, nuclear magnetic resonance (NMR) spectroscopy, and structural characterization by X-ray crystallography. Included in this series of catalysts were 13 catalysts bearing alkoxy groups with varied steric bulk on the chelating benzylidene, ranging from ethoxy to dicyclohexylmethoxy groups. The experimentally observed initiation kinetics of the synthesized catalysts were in good accordance with computational predictions. Notably, the fast initiation rate of the dicyclohexylmethoxy catalyst was successfully predicted by the model, and this complex is believed to be among the fastest initiating Hoveyda–Grubbs-type catalysts reported to date. The compatibility of the predictive model with other catalyst families, including those bearing alternative N-heterocyclic carbene (NHC) ligands or disubstituted alkoxy benzylidenes, was also examined

Elderly with Autism: Executive Functions and Memory

Cognitive autism research is mainly focusing on children and young adults even though we know that autism is a life-long disorder and that healthy aging already has a strong impact on cognitive functioning. We compared the neuropsychological profile of 23 individuals with autism and 23 healthy controls (age range 51–83 years). Deficits were observed in attention, working memory, and fluency. Aging had a smaller impact on fluency in the high functioning autism (HFA) group than in the control group, while aging had a more profound effect on visual memory performance in the HFA group. Hence, we provide novel evidence that elderly with HFA have subtle neuropsychological deficits and that the developmental trajectories differ between elderly with and without HFA in particular cognitive domains