Remote capacitive sensing in two-dimension quantum-dot arrays

We investigate gate-defined quantum dots in silicon on insulator nanowire field-effect transistors fabricated using a foundry-compatible fully-depleted silicon-on-insulator (FD-SOI) process. A series of split gates wrapped over the silicon nanowire naturally produces a $2\times n$ bilinear array of quantum dots along a single nanowire. We begin by studying the capacitive coupling of quantum dots within such a 2$\times$2 array, and then show how such couplings can be extended across two parallel silicon nanowires coupled together by shared, electrically isolated, 'floating' electrodes. With one quantum dot operating as a single-electron-box sensor, the floating gate serves to enhance the charge sensitivity range, enabling it to detect charge state transitions in a separate silicon nanowire. By comparing measurements from multiple devices we illustrate the impact of the floating gate by quantifying both the charge sensitivity decay as a function of dot-sensor separation and configuration within the dual-nanowire structure.Comment: 9 pages, 3 figures, 35 cites and supplementar

Cloning of the rice Xo1 resistance gene and interaction of the Xo1 protein with the defense-suppressing Xanthomonas effector Tal2h

The Xo1 locus in the heirloom rice variety Carolina Gold Select confers resistance to bacterial leaf streak and bacterial blight, caused by Xanthomonas oryzae pv. oryzicola and X. oryzae pv. oryzae, respectively. Resistance is triggered by pathogen-delivered transcription activator-like effectors (TALEs) independent of their ability to activate transcription and is suppressed by truncated variants called truncTALEs, common among Asian strains. By transformation of the susceptible variety Nipponbare, we show that one of 14 nucleotide-binding, leucine-rich repeat (NLR) protein genes at the locus, with a zinc finger BED domain, is the Xo1 gene. Analyses of published transcriptomes revealed that the Xo1-mediated response is more similar to those mediated by two other NLR resistance genes than it is to the response associated with TALE-specific transcriptional activation of the executor resistance gene Xa23 and that a truncTALE dampens or abolishes activation of defense-associated genes by Xo1. In Nicotiana benthamiana leaves, fluorescently tagged Xo1 protein, like TALEs and truncTALEs, localized to the nucleus. And endogenous Xo1 specifically coimmunoprecipitated from rice leaves with a pathogen-delivered, epitope-tagged truncTALE. These observations suggest that suppression of Xo1-function by truncTALEs occurs through direct or indirect physical interaction. They further suggest that effector coimmunoprecipitation may be effective for identifying or characterizing other resistance genes

Pauli spin blockade in CMOS double quantum dot devices

Silicon quantum dots are attractive candidates for the development of scalable, spin-based qubits. Pauli spin blockade in double quantum dots provides an efficient, temperature independent mechanism for qubit readout. Here we report on transport experiments in double gate nanowire transistors issued from a CMOS process on 300 mm silicon-on-insulator wafers. At low temperature the devices behave as two few-electron quantum dots in series. We observe signatures of Pauli spin blockade with a singlet-triplet splitting ranging from 0.3 to 1.3 meV. Magneto-transport measurements show that transitions which conserve spin are shown to be magnetic-field independent up to B = 6 T.Comment: 5 pages , 4 figure

A CMOS silicon spin qubit

Silicon, the main constituent of microprocessor chips, is emerging as a promising material for the realization of future quantum processors. Leveraging its well-established complementary metal-oxide-semiconductor (CMOS) technology would be a clear asset to the development of scalable quantum computing architectures and to their co-integration with classical control hardware. Here we report a silicon quantum bit (qubit) device made with an industry-standard fabrication process. The device consists of a two-gate, p-type transistor with an undoped channel. At low temperature, the first gate defines a quantum dot (QD) encoding a hole spin qubit, the second one a QD used for the qubit readout. All electrical, two-axis control of the spin qubit is achieved by applying a phase-tunable microwave modulation to the first gate. Our result opens a viable path to qubit up-scaling through a readily exploitable CMOS platform.Comment: 12 pages, 4 figure

Programming the assembly of carboxylic acid-functionalised hybrid polyoxometalates

We report here the straightforward synthesis and characterisation of a series Anderson-type hybrid polyoxometalates in high yield, functionalised with carboxylic acid following the reaction of anhydride precursors with the starting hybrid cluster ([n-N(C4H9)4]3[MnMo6O18((OCH2)3CNH2)2]). Seven new structures have been obtained, five of which have acid-terminated ligands. Six of these structures have been isolated with a yield higher than 80% with high purity. This reaction is limited by the bulkiness of the anhydride used; this effect can be employed to selectively synthesise one isomer out of three other possibilities. The acid groups and aromatic platforms attached to the clusters can act as building tools to bridge several length scales and engineer molecular packing within the crystal structure. The presence of acids should also change the hydrophilicity of the clusters, and therefore the way they interact with hydrophilic surfaces. We also show a potential relationship between the acid group interaction in the packing diagram and the cluster’s tendency to interact with a hydrophilic surface. In addition to reporting a derived synthetic path to new acid-terminated Mn-Anderson-type hybrids, we describe here a new way to program self-assembly motifs of these compounds in the crystal structure and at interfaces

Additional resource needs for viral hepatitis elimination through universal health coverage : projections in 67 low-income and middle-income countries, 2016–30

Background: The World Health Assembly calls for elimination of viral hepatitis as a public health threat by 2030 (ie, −90% incidence and −65% mortality). However, WHO's 2017 cost projections to achieve health-related Sustainable Development Goals did not include the resources needed for hepatitis testing and treatment. We aimed to estimate the incremental commodity cost of adding scaled up interventions for testing and treatment of hepatitis to WHO's investment scenarios. Methods: We added modelled costs for implementing WHO recommended hepatitis testing and treatment to the 2017 WHO cost projections. We quantified additional requirements for diagnostic tests, medicines, health workers' time, and programme support across 67 low-income and middle-income countries, from 2016–30. A progress scenario scaled up interventions and a more ambitious scenario was modelled to reach elimination by 2030. We used 2018 best available prices of diagnostics and generic medicines. We estimated total costs and the additional investment needed over the projection of the 2016 baseline cost. Findings: The 67 countries considered included 230 million people living with hepatitis B virus (HBV) and 52 million people living with hepatitis C virus (HCV; 90% and 73% of the world's total, respectively). Under the progress scenario, 3250 million people (2400 million for HBV and 850 million for HCV) would be tested and 58·2 million people (24·1 million for HBV and 34·1 million for HCV) would be treated (total additional cost US$27·1 billion). Under the ambitious scenario, 11 631 million people (5502 million for HBV and 6129 million for HCV) would be tested and 93·8 million people (32·2 million for HBV and 61·6 million for HCV) would be treated (total additional cost$58·7 billion), averting 4·5 million premature deaths and leading to a gain of 51·5 million healthy life-years by 2030. However, if affordable HCV medicines remained inaccessible in 13 countries where medicine patents are protected, the additional cost of the ambitious scenario would increase to $118 billion. Hepatitis elimination would account for a 1·5% increase to the WHO ambitious health-care strengthening scenario costs, avert an additional 4·6% premature deaths, and add an additional 9·6% healthy life-years from 2016–30. Interpretation: Access to affordable medicines in all countries will be key to reach hepatitis elimination. This study suggests that elimination is feasible in the context of universal health coverage. It points to commodities as key determinants for the overall price tag and to options for cost reduction strategies. Funding: WHO, United States Centers for Disease Control and Prevention, Unitaid