Manipulation of Ca+ Ions in Penning Traps

The long term aim of this work is to study the suitability of using laser cooled Ca+ ions in Penning traps as the basic components of a quantum computer. A great deal of progress in the field of quantum computing has been made in recent years with laser cooled ions stored in radio frequency ion traps. Building a useful quantum computer with trapped ions is however extremely challenging. Penning traps offer some possible benefits over radio frequency traps. They also create some additional difficulties. The potential advantages and disadvantages of Penning traps are discussed throughout the thesis. We show that we are able to overcome the problems associated with laser cooling in Penning traps, and have trapped single ions for extended periods of time. Pairs of Ca+ ions have been aligned along the axis of a Penning trap, and have been optically resolved. A novel Penning trap array based on PCB boards has been developed. A prototype was built and tested, along with the electronics required to shuttle ions between different sub-traps. Ions have been shuttled a distance of 10 mm in 2.5 μs. A return trip efficiency of up to 75% was seen. A quantum effect – J-state mixing caused by large magnetic fields – has been observed for the first time in single atomic ions. The magnetic field causes a forbidden [Delta]J = 2 transition to become weakly allowed. This effect is of general interest in atomic physics, and is also very relevant for quantum computation studies. A quantitative prediction of the magnitude of the J-mixing effect has been derived theoretically. This is compared to experimental data, and is found to be in excellent qualitative and good quantitative agreement

Approaches for Evaluating and Engineering Resilient Superhydrophobic Materials

Superhydrophobic materials rely upon highly rough surface morphologies in order to maximise water repellency, and requires surface features on the micro/nanoscale. These tremendously small surface structures are inherently physically weak, relative to characteristics of bulk materials. This limits the real-world applicability of many superhydrophobic surfaces, as degradation and loss of superhydrophobicity readily occurs upon exposure to anticipated stimuli. Consequently, there is an absence of long-lasting commercial products, but instead rely upon frequent regeneration. These materials demonstrate a tremendous potential for application in a range of areas, including antifouling, self-cleaning, drag-reduction, anti-icing, etc. To realise application on these fields, superhydrophobic resilience must be maximised. This chapter summarises evaluation methods and engineering procedures in attaining resilience, both are highly important in the development of robust materials

Novel designs for Penning ion traps

We present a number of alternative designs for Penning ion traps suitable for quantum information processing (QIP) applications with atomic ions. The first trap design is a simple array of long straight wires which allows easy optical access. A prototype of this trap has been built to trap Ca+ and a simple electronic detection scheme has been employed to demonstrate the operation of the trap. Another trap design consists of a conducting plate with a hole in it situated above a continuous conducting plane. The final trap design is based on an array of pad electrodes. Although this trap design lacks the open geometry of the traps described above, the pad design may prove useful in a hybrid scheme in which information processing and qubit storage take place in different types of trap. The behaviour of the pad traps is simulated numerically and techniques for moving ions rapidly between traps are discussed. Future experiments with these various designs are discussed. All of the designs lend themselves to the construction of multiple trap arrays, as required for scalable ion trap QIP.Comment: 11 pages, 10 figure

PCA and K-Means decipher genome

In this paper, we aim to give a tutorial for undergraduate students studying statistical methods and/or bioinformatics. The students will learn how data visualization can help in genomic sequence analysis. Students start with a fragment of genetic text of a bacterial genome and analyze its structure. By means of principal component analysis they ``discover'' that the information in the genome is encoded by non-overlapping triplets. Next, they learn how to find gene positions. This exercise on PCA and K-Means clustering enables active study of the basic bioinformatics notions. Appendix 1 contains program listings that go along with this exercise. Appendix 2 includes 2D PCA plots of triplet usage in moving frame for a series of bacterial genomes from GC-poor to GC-rich ones. Animated 3D PCA plots are attached as separate gif files. Topology (cluster structure) and geometry (mutual positions of clusters) of these plots depends clearly on GC-content.Comment: 18 pages, with program listings for MatLab, PCA analysis of genomes and additional animated 3D PCA plot

Intelligent systems in the context of surrounding environment

We investigate the behavioral patterns of a population of agents, each controlled by a simple biologically motivated neural network model, when they are set in competition against each other in the Minority Model of Challet and Zhang. We explore the effects of changing agent characteristics, demonstrating that crowding behavior takes place among agents of similar memory, and show how this allows unique `rogue' agents with higher memory values to take advantage of a majority population. We also show that agents' analytic capability is largely determined by the size of the intermediary layer of neurons. In the context of these results, we discuss the general nature of natural and artificial intelligence systems, and suggest intelligence only exists in the context of the surrounding environment (embodiment). Source code for the programs used can be found at http://neuro.webdrake.net/

Towards Analytics for Wholistic School Improvement: Hierarchical Process Modelling and Evidence Visualization

Central to the mission of most educational institutions is the task of preparing the next generation of citizens to contribute to society. Schools, colleges, and universities value a range of outcomes — e.g., problem solving, creativity, collaboration, citizenship, service to community — as well as academic outcomes in traditional subjects. Often referred to as “wider outcomes,” these are hard to quantify. While new kinds of monitoring technologies and public datasets expand the possibilities for quantifying these indices, we need ways to bring that data together to support sense-making and decision-making. Taking a systems perspective, the hierarchical process modelling (HPM) approach and the “Perimeta” visual analytic provides a dashboard that informs leadership decision-making with heterogeneous, often incomplete evidence. We report a prototype of Perimeta modelling from education, aggregating wider outcomes data across a network of schools, and calculating their cumulative contribution to key performance indicators, using the visual analytic of the Italian flag to make explicit not only the supporting evidence, but also the challenging evidence, as well as areas of uncertainty. We discuss the nature of the modelling decisions and implicit values involved in quantifying these kinds of educational outcomes