Suppressing qubit dephasing using real-time Hamiltonian estimation

Unwanted interaction between a quantum system and its fluctuating environment leads to decoherence and is the primary obstacle to establishing a scalable quantum information processing architecture. Strategies such as environmental and materials engineering, quantum error correction and dynamical decoupling can mitigate decoherence, but generally increase experimental complexity. Here we improve coherence in a qubit using real-time Hamiltonian parameter estimation. Using a rapidly converging Bayesian approach, we precisely measure the splitting in a singlet-triplet spin qubit faster than the surrounding nuclear bath fluctuates. We continuously adjust qubit control parameters based on this information, thereby improving the inhomogenously broadened coherence time from tens of nanoseconds to >2 μs. Because the technique demonstrated here is compatible with arbitrary qubit operations, it is a natural complement to quantum error correction and can be used to improve the performance of a wide variety of qubits in both meteorological and quantum information processing applications

The Internet of Things: New Interoperability, Management and Security Challenges

The Internet of Things (IoT) brings connectivity to about every objects found in the physical space. It extends connectivity to everyday objects. From connected fridges, cars and cities, the IoT creates opportunities in numerous domains. However, this increase in connectivity creates many prominent challenges. This paper provides a survey of some of the major issues challenging the widespread adoption of the IoT. Particularly, it focuses on the interoperability, management, security and privacy issues in the IoT. It is concluded that there is a need to develop a multifaceted technology approach to IoT security, management, and privacy.Comment: 18 pages, International Journal of Network Security & Its Applications (IJNSA) Vol.8, No.2, March 201

Extending the performance of hybrid NoCs beyond the limitations of network heterogeneity

To meet the performance and scalability demands of the fast-paced technological growth towards exascale and Big-Data processing with the performance bottleneck of conventional metal based interconnects (wireline), alternative interconnect fabrics such as inhomogeneous three-dimensional integrated Network-on-Chip (3D NoC) and hybrid wired-wireless Network-on-Chip (WiNoC) have emanated as a cost-effective solution for emerging System-on-Chip (SoC) design. However, these interconnects trade-off optimized performance for cost by restricting the number of area and power hungry 3D routers and wireless nodes. Moreover, the non-uniform distributed traffic in chip multiprocessor (CMP) demands an on-chip communication infrastructure which can avoid congestion under high traffic conditions while possessing minimal pipeline delay at low-load conditions. To this end, in this paper, we propose a low-latency adaptive router with a low-complexity single-cycle bypassing mechanism to alleviate the performance degradation due to the slow 2D routers in such emerging hybrid NoCs. The proposed router transmits a flit using dimension-ordered routing (DoR) in the bypass datapath at low-loads. When the output port required for intra-dimension bypassing is not available, the packet is routed adaptively to avoid congestion. The router also has a simplified virtual channel allocation (VA) scheme that yields a non-speculative low-latency pipeline. By combining the low-complexity bypassing technique with adaptive routing, the proposed router is able balance the traffic in hybrid NoCs to achieve low-latency communication under various traffic loads. Simulation shows that, the proposed router can reduce applications’ execution time by an average of 16.9% compared to low-latency routers such as SWIFT. By reducing the latency between 2D routers (or wired nodes) and 3D routers (or wireless nodes) the proposed router can improve performance efficiency in terms of average packet delay by an average of 45% (or 50%) in 3D NoCs (or WiNoCs)

Renewables 2005: Global Status Report

The Global Status Report provides an assessment of several renewables technologies -- small hydro, modern biomass, wind, solar, geothermal, and biofuels -- that are now competing with conventional fuels in four distinct markets: power generation, hot water and space heating, transportation fuels, and rural (off-grid) energy supplies. The report finds that government support for renewable energy is growing rapidly. At least 48 countries now have some type of renewable energy promotion policy, including 14 developing countries. Most targets are for shares of electricity production, typically 5-30 percent, by the 2010-2012 timeframe. Mandates for blending biofuels into vehicle fuels have been enacted in at least 20 states and provinces worldwide as well as in three key countries -- Brazil, China and India. Government leadership provides the key to market success, according to the report. The market leaders in renewable energy in 2004 were Brazil in biofuels, China in solar hot water, Germany in solar electricity, and Spain in wind power. The Global Status Report fills a gap in the international energy reporting arena, which has tended to neglect the emerging renewable energy technologies. Regular updates will be produced in the future. The report was produced and published by the Worldwatch Institute and released today at the Beijing International Renewable Energy Conference 2005, sponsored by the Government of China. This Conference brings together government and private leaders from around the world, providing a forum for international leadership on renewable energy and connects the wide variety of stakeholders that came together at the International Conference for Renewable Energies in Bonn, Germany, in 2004. The creation of REN21 was sponsored by the German Federal Ministry for Economic Cooperation and Development and the German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety. Formally established in Copenhagen in June 2005, REN21 is now supported by a steering committee of 11 governments, 5 intergovernmental organizations, 5 non-governmental organizations, and several regional, local, and private organizations

Weakly nonlinear circuit analysis based on fast multidimensional inverse Laplace transform

There have been continuing thrusts in developing efficient modeling techniques for circuit simulation. However, most circuit simulation methods are time-domain solvers. In this paper we propose a frequency-domain simulation method based on Laguerre function expansion. The proposed method handles both linear and nonlinear circuits. The Laguerre method can invert multidimensional Laplace transform efficiently with a high accuracy, which is a key step of the proposed method. Besides, an adaptive mesh refinement (AMR) technique is developed and its parallel implementation is introduced to speed up the computation. Numerical examples show that our proposed method can accurately simulate large circuits while enjoying low computation complexity. © 2012 IEEE.published_or_final_versio

The Medical Genome Reference Bank contains whole genome and phenotype data of 2570 healthy elderly

Population health research is increasingly focused on the genetic determinants of healthy ageing, but there is no public resource of whole genome sequences and phenotype data from healthy elderly individuals. Here we describe the first release of the Medical Genome Reference Bank (MGRB), comprising whole genome sequence and phenotype of 2570 elderly Australians depleted for cancer, cardiovascular disease, and dementia. We analyse the MGRB for single-nucleotide, indel and structural variation in the nuclear and mitochondrial genomes. MGRB individuals have fewer disease-associated common and rare germline variants, relative to both cancer cases and the gnomAD and UK Biobank cohorts, consistent with risk depletion. Age-related somatic changes are correlated with grip strength in men, suggesting blood-derived whole genomes may also provide a biologic measure of age-related functional deterioration. The MGRB provides a broadly applicable reference cohort for clinical genetics and genomic association studies, and for understanding the genetics of healthy ageing