Graphics Processing Unit-Accelerated Numerical Simulations and Theoretical Study of Qubit Dynamics in Realistic Systems

Quantum computers are thought to be the future of computation, using the properties of quantum mechanics to solve problems intractable to classical computers. Quantum computing leverages non-classical properties, such as entanglement, to achieve an exponential improvement in computational power. A quantum computer would enable us to address many real-world problems, such as how to synthesize fertilizers more efficiently; how to combat global warming; or to simulate protein folding in biological systems. Although much work has been done to describe the use and implementation of entanglement generation theoretically, it is still a challenge to develop such protocols experimentally. The bulk of this work is focused on creating Graphics Processing Unit (GPU)-accelerated computer simulations of quantum systems with advanced numerical and analytical techniques. Simulations can guide experiments attempting to create building blocks of quantum computers - qubits and their control devices. However, simulation of more realistic device setups in two dimensional systems has been facing problems owing to the space and time domain scaling associated with the solutions of the many-particle time dependent Schrodinger equation (TDSE). Nevertheless, recent advances in computer hardware performance has made previously intractable two-particle problems readily solvable. I have developed custom GPU-accelerated software based on a staggered-leapfrog algorithm that opens up new possibilities of simulating two-dimensional two-particle systems accurately. I focus on three research projects. Firstly, optimally defining a charge-based solid state qubit, and controlling it in a simple and experimentally achievable way, while accounting for imperfections of the waveform generators. I simulate the physical qubit on a fine-grained lattice, and propose an innovative control scheme that accounts for finite rise/fall time of the experimental apparatus, while being relatively fast and resulting in very high operation fidelity. An optimal pulsing scheme with rise time-dependent parameters is found, and shown to be able to achieve an arbitrary qubit rotation. Since the proposed pulse sequence reduces to sine waves to minimize total pulse duration, it is straightforward to implement experimentally, and easily generalisable to different systems. I also show how the fidelity remains sufficiently high independently of the initial qubit state. The proposed sequence can even reduce errors caused by charge noise under certain conditions. Readout techniques are discussed as well, and found to not present significant issues. Secondly, I aid the effort to create a Surface Acoustic Wave quantum computer prototype by describing how to produce an universal quantum gate set with a Root-of-SWAP operation used as a physical two-qubit gate. Using realistic parameters, it is shown how this operation can be performed with high fidelity. Previous work has been done to simulate a proposed Root-of-SWAP method in one dimension - this work focuses on extending this to two dimensions. We find that the method of generating Root-of-SWAP mentioned above breaks down in two dimensions- unwanted excitations are introduced in the extra dimension, causing a phase difference to appear, and thus ruining coherence of the state. I propose to implement the Root-of-SWAP operation via a tunneling interaction across the effective double dot instead. This was previously considered, however was thought to be unstable against variations in tunnel barrier height, which has exponential impact on the speed of the quantum operation. Using newly available computing power, we were able to run detailed two dimensional simulations investigating this method and its robustness against variations in the double dot potential. We find that the method produces high fidelity Root-of-SWAP states, and is robust against small variations in the tunnel barrier. Additionally, we find a relation between the tunnel barrier height and spin measurement probability, providing a way for experimentalists to estimate an actual device barrier indirectly. Finally, I theoretically model and simulate transport through a single electron transistor (SET) device. It is shown that a single donor structure can reliably be engineered from doped quantum dots by taking advantage of the tunability of the electron tunneling rates as well as the interplay, at low temperatures, between disorder conferred by randomness in dopant distribution and electron-electron interaction originating from the high doping concentration. It is possible to electrostatically isolate a single donor from the large ensemble of dopants. I investigate how such a complex system is expected to conduct, and verify a hypothesis that two donors take part in the transport by numerically reproducing the experimental measurements. Finally, it is shown that this device can be used as a single atom detector of the charge occupancy of a nearby capacitively coupled double quantum dot. While this final part does not make use of the GPU-accelerated software, it is still closely related to the rest of this work, and the theme of modeling realistic quantum devices.Project for Developing Innovation Systems of the Ministry of Education, Culture, Sports, Science and Technology (MEXT) Engineering and Physical Sciences Research Council (EPSRC) and Hitachi via CASE studentships RG 9463

A Phenomenological Study Exploring an Infertile Christian Woman\u27s Experience from Clergy Counseling in a Local Church

The purpose of this phenomenological study was to discover the perceptions of infertile women’s perceived experiences with receiving counseling from their local church pastor. The theories guiding this study were identity theory and narrative identity theory, as an infertile woman often feels a loss in their identity due to not being able to become a mother. This study explored how an infertile woman had hope to identify as a mother perceived counseling from her local church. The central research question for this transcendental phenomenological study was: How does a Christian woman who is coping with infertility describe the impact of clergy counseling from her church pastors on mental health and well-being? Data were collected through questionnaires to find participants that fit the criteria for the study. Semi-structured interviews were audio-recorded and transcribed to look for themes. Data analysis was accomplished in a seven-step process that involved organizing, coding, and interpreting the data. This was accomplished by reviewing the transcripts of the interviews several times while taking notes, looking for themes, coding and organizing them, interpreting the themes, and getting feedback from a peer unrelated to the study. The results of this study found themes from the interviews that infertile women found ways to positively cope and to get help through clergy counsel for issues such as identity loss, marital struggles, and social issues

The Elements of Comedy and Parody in the Dionysiaca of Nonnus

In this article the author presents the elements of comedy and parody in the Dionysiaca of Nonnus. The analysis of the passages excerpted from the Dionysiaka shows that the composition of Nonnus’ poem is based on the principle of generic variety

ENERGY UTILIZATION AND NUTRITIVE VALUE OF MAIZE GRAIN CULTIVARS FOR BROILER CHICKENS

The purpose of the study was to determine nutrients digestibility and energy utilization of nine maize cultivars (Opoka, Boruta, Nysa, Smok, Pioneer PR39H64, Monada, Rustika Eurostar, Pionier G12, Arobase) in broiler chickens. Cultivars differed in a content of CP and EE. In vivo digestibility was measured by a standard method on ninety 42 days old broilers. CP digestibility was calculated using the α-amino nitrogen method. Furthermore, digestible energy (DE) and apparent metabolizable energy (AMEN) as well as nitrogen balance and retention were determined. Maize grain nutritive value and energy utilization in broiler chickens depended on the cultivars. The cultivars characterized by higher content of CP and EE had higher digestibility coeffi cient of these nutrients. The cultivar did not infl uence nitrogen balance and retention. It is recommended to take into a consideration the maize grain cultivars and their chemical composition when a broiler diet is being composed

Axonal maintenance, glia, exosomes, and heat shock proteins

© The Author(s), 2016. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in F1000Research 5 (2016): 205, doi:10.12688/f1000research.7247.1.Of all cellular specializations, the axon is especially distinctive because it is a narrow cylinder of specialized cytoplasm called axoplasm with a length that may be orders of magnitude greater than the diameter of the cell body from which it originates. Thus, the volume of axoplasm can be much greater than the cytoplasm in the cell body. This fact raises a logistical problem with regard to axonal maintenance. Many of the components of axoplasm, such as soluble proteins and cytoskeleton, are slowly transported, taking weeks to months to travel the length of axons longer than a few millimeters after being synthesized in the cell body. Furthermore, this slow rate of supply suggests that the axon itself might not have the capacity to respond fast enough to compensate for damage to transported macromolecules. Such damage is likely in view of the mechanical fragility of an axon, especially those innervating the limbs, as rapid limb motion with high impact, like running, subjects the axons in the limbs to considerable mechanical force. Some researchers have suggested that local, intra-axonal protein synthesis is the answer to this problem. However, the translational state of axonal RNAs remains controversial. We suggest that glial cells, which envelop all axons, whether myelinated or not, are the local sources of replacement and repair macromolecules for long axons. The plausibility of this hypothesis is reinforced by reviewing several decades of work on glia-axon macromolecular transfer, together with recent investigations of exosomes and other extracellular vesicles, as vehicles for the transmission of membrane and cytoplasmic components from one cell to another.Harold Gainer’s contribution to this research was supported by the Intramural Research Program of the NINDS, NIH

Acute neurological symptoms of Moschcowitz disease—Case report

Thrombotic thrombocytopenic purpura (TTP, Moschcowitz disease) is characterized by thrombotic microangiopathy leading to microvascular occlusion and ischemic dysfunction of various organs including the brain. In the course of the rare disease most patients develop neurological symptoms of varying severity and characteristics. The case presented is that of a 34-year-old female patient with profound thrombocytopenia, anemia and rapidly progressive neurological deterioration into coma with normal result of brain imaging. TTP was recognized on the basis of hematological analysis. The initiated steroid therapy and plasma exchange failed to prevent the turbulent course of disease in the patient, who died exhibiting symptoms of multiple organ failure caused by thrombotic microangiopathy. TTP remains to be a diagnostic challenge, particularly in the case of atypical symptoms or when neuroimaging and laboratory results are inconclusive. Before using the corticosteroids and plasma exchange, TTP had a case fatality rate of approx. 90% (Podolak-Dawidziak, 2013). Nowadays recovery is possible when vigorous treatment is introduced early in the course of this disease

Elektrokemijsko ispitivanje stabilnosti pasivnog stanja i korozijske otpornosti supermartenzitnog nehrđajućeg čelika

On low interstitial - supermartensitic stainless steels (X1CrNiMo 12-5-1, X2CrNiMo 13-6-2, X1CrNiMo 12-6-2) the electrochemical potentiodynamic polarization tests were carried out and the passive state stability and localized corrosion resistance were compared and evaluated. The effect of quenching and tempering as well as the changes in microstructure on polarisation curves and corrosion properties at room temperature were established. Small differences in chemical composition of steels were also registered on their corrosion parameters changes and resistance.Rad prikazuje usporedbu i procjenu stabilnosti pasivnog stanja i lokalnu otpornost koroziji temeljem ispitivanja elektrokemijske potenciodinamičke polarizacije nisko-intersticijskih supermartenzitnih nehrđajućih čelika (X1CrNiMo 12-5-1, X2CrNiMo 13-6-2, X1CrNiMo 12-6-2). Utvrđeni su utjecaj poboljšavanja čelika i mikrostrukturne promjene na polarizacijskim krivuljama uzoraka te korozijska svojstva pri sobnoj temperaturi. Uočena je i povezanost malih odstupanja kemijskog sastava čelika s promjenom korozijskih parametera i korozijskom otpornošću