Topological Features in Ion Trap Holonomic Computation

Topological features in quantum computing provide controllability and noise error avoidance in the performance of logical gates. While such resilience is favored in the manipulation of quantum systems, it is very hard to identify topological features in nature. This paper proposes a scheme where holonomic quantum gates have intrinsic topological features. An ion trap is employed where the vibrational modes of the ions are coherently manipulated with lasers in an adiabatic cyclic way producing geometrical holonomic gates. A crucial ingredient of the manipulation procedures is squeezing of the vibrational modes, which effectively suppresses exponentially any undesired fluctuations of the laser amplitudes, thus making the gates resilient to control errors.Comment: 9 pages, 4 figures, REVTE

Best-case performance of quantum annealers on native spin-glass benchmarks: How chaos can affect success probabilities

Recent tests performed on the D-Wave Two quantum annealer have revealed no clear evidence of speedup over conventional silicon-based technologies. Here, we present results from classical parallel-tempering Monte Carlo simulations combined with isoenergetic cluster moves of the archetypal benchmark problem-an Ising spin glass-on the native chip topology. Using realistic uncorrelated noise models for the D-Wave Two quantum annealer, we study the best-case resilience, i.e., the probability that the ground-state configuration is not affected by random fields and random-bond fluctuations found on the chip. We thus compute classical upper-bound success probabilities for different types of disorder used in the benchmarks and predict that an increase in the number of qubits will require either error correction schemes or a drastic reduction of the intrinsic noise found in these devices. We outline strategies to develop robust, as well as hard benchmarks for quantum annealing devices, as well as any other computing paradigm affected by noise.Comment: 8 pages, 5 figure

Low Carbon Land Use: Paris, Pittsburgh, and the IPCC

This article describes strategies that local governments are employing to both mitigate and adapt to climate change, using their state-given powers to plan community development and to regulate private building. Local governments have significant legal authority to shape human settlements and, in so doing, lower CO2 emissions from buildings and vehicles, increase the sequestration of carbon by the natural environment, and promote distributed energy systems and renewable energy facilities that lower fossil fuel consumption. Local elected leaders are highly motivated to avoid the on-the-ground consequences of our changing climate. The effects of climate change manifest themselves at the local level, where people are killed or injured, property is destroyed, businesses are shuttered, ecosystems are fouled, and where our democratic system is most vibrant and able to respond. In 2014, the international community caught up with local governments in the global race against climate change. That year the Intergovernmental Panel on Climate Change embraced the critical role of municipal governments in mitigating the causes of climate change. In 2015, the Paris Climate Agreement adopted by the Conference of the Parties followed suit. This has encouraged localities to redouble their efforts and creates new and exciting opportunities for intergovernmental partnerships to manage climate change