Randomized benchmarking in measurement-based quantum computing

Randomized benchmarking is routinely used as an efficient method for characterizing the performance of sets of elementary logic gates in small quantum devices. In the measurement-based model of quantum computation, logic gates are implemented via single-site measurements on a fixed universal resource state. Here we adapt the randomized benchmarking protocol for a single qubit to a linear cluster state computation, which provides partial, yet efficient characterization of the noise associated with the target gate set. Applying randomized benchmarking to measurement-based quantum computation exhibits an interesting interplay between the inherent randomness associated with logic gates in the measurement-based model and the random gate sequences used in benchmarking. We consider two different approaches: the first makes use of the standard single-qubit Clifford group, while the second uses recently introduced (non-Clifford) measurement-based 2-designs, which harness inherent randomness to implement gate sequences.Comment: 10 pages, 4 figures, comments welcome; v2 published versio

Electrification of Urban Freight Transport - a Case Study of the Food Retailing Industry

Decarbonisation is a major challenge for the coming decades, for all industries, including the transport sector. Battery electric vehicles are a potential solution for the transport sector to reduce its carbon impact. Asides from the question whether there is sufficient supply of electric vehicles for freight transport, it is also unclear whether battery-powered trucks meet the practical requirements, especially in terms of their driving range. To investigate this, synthetic tours were generated by solving a Vehicle Routing Problem (VRP). This also generates the fleet size and composition depending on a set of different vehicle types. The network with underlying traffic conditions comes from an publicly available transport model. The generated tours are then simulated with an open-source transport simulation (MATSim), for both diesel and battery electric vehicles (BEVs). In a sensitivity study, two different purchase prices were considered for calculating vehicle costs. The case study uses a model of the food retailing industry for the city of Berlin. 56% of the tours can be driven without recharging. When recharged one time, 90% of the tours are suitable for BEVs. The costs for transporting the goods will increase by 17 to 23% depending on the assumption for the purchase prices for the BEVs. Using a well-to-wheel calculation, the electrification of all tours leads to a reduction of greenhouse gas (GHG) emissions by 26 to 96% depending on the assumed electricity production.DFG, 398051144, Analyse von Strategien zur vollständigen Dekarbonisierung des urbanen Verkehr

Proton Beam Defocusing as a Result of Self-Modulation in Plasma

The AWAKE experiment will use a \SI{400}{GeV/c} proton beam with a longitudinal bunch length of $\sigma_z = 12\,\rm{cm}$ to create and sustain GV/m plasma wakefields over 10 meters . A 12 cm long bunch can only drive strong wakefields in a plasma with $n_{pe} = 7 \times 10^{14}\,\rm{electrons/cm}^3$ after the self-modulation instability (SMI) developed and microbunches formed, spaced at the plasma wavelength. The fields present during SMI focus and defocus the protons in the transverse plane \cite{SMI}. We show that by inserting two imaging screens downstream the plasma, we can measure the maximum defocusing angle of the defocused protons for plasma densities above $n_{pe} = 5 \times 10^{14}\,\rm{electrons/cm}^{-3}$. Measuring maximum defocusing angles around 1 mrad indirectly proves that SMI developed successfully and that GV/m plasma wakefields were created. In this paper we present numerical studies on how and when the wakefields defocus protons in plasma, the expected measurement results of the two screen diagnostics and the physics we can deduce from it.Comment: 3 pages, 2 figures, Conference Proceedings of NAPAC 201

The educational ideas and influence of Thomas Robert Malthus (1766-1834)

In this study, the depth of Malthus's involvement in education will be seen. During his years at Haileybury College, Malthus proved himself to be a caring and conscientious teacher who, as will be demonstrated in Chapter III, was remembered with affection in later life by many of his pupils; he was a loyal member of staff who defended the college against critical reports in the press; he was concerned about the welfare of the boys in his charge, as well as an appropriate curriculum for them and fair methods of assessing their progress. A detailed examination of biographies, letters and published articles will provide ample evidence to prove these claims about Malthus. The criticism has sometimes been made that Malthus wished to condemn the poor to a life made even more difficult by the withdrawal of the assistance offered by the Poor Laws, but the analysis of his theories which appears in Chapters V and VI of this study will demonstrate that this was not Malthus's intention. Far from wanting the poor to suffer increased privation, Malthus hoped that his proposals would offer them the chance to improve their situation and influence their own destiny. A critical study of his own words will show the importance of education in his vision of a better future. An education populace would understand the reasons behind food shortage and would appreciate the necessity of delaying marriage, thereby slowing down the increase in population. Education would encourage the lower classes to strive for self-improvement; it would show them how to be careful and plan for the future; it would `have a considerable effect in the prevention of crimes and the promotion of industry, morality and regular conduct'(2); it would even bring about a more peaceful and stable society as an educated populace would understand the truth about their situation and would not be persuaded by the `false declamation of interested and ambitious demagogues'(3). It is certainly true that Malthus recommended the abolition of the existing Poor Laws, but this does not mean that he wished to condemn the poor to increased suffering. On the contrary, an examination of the historical background of the system of poor relief at the end of the eighteenth century and the beginning of the nineteenth century will help us to understand Malthus's attitude to the Poor Laws, and a detailed analysis of his own proposals in Chapter VI of this study will explain how his ideas about Poor Law reform were linked to his theories about social and economic reform. Finally, Chapters VIII, IX and X of this study will contain an examination of the extent of the influence exerted on public opinion by Malthus and his theories

Master of Science

thesisMaterials that have feature sizes on the mesoscale present unique properties based on diffusion and chemical reactions. Despite the breadth of work done in this area, there is little work done connecting biological mesostructures and the well-developed inorganic mesoporous materials. This thesis presents work done on mesostructured and mesoporous materials to connect biological mesostructures to the field of inorganic mesoporous materials. Specifically, we have developed novel methods for making self-assembled biological-inorganic mesoporous composites, densified mesoporous solids, and investigated tunability of mesostructured biological emulsions (cubosomes). Cubosomes were investigated for tunability of the lattice parameter via addition of a designer peptide and was characterized by cryogenic transmission electron microscopy and small-angle x-ray scattering, which revealed a swelling of the lattice parameter and the appearance of a hexagonal phase at low peptide concentrations. Self-assembled biological-inorganic composite materials was shown to possess order on the mesoscale when observed by transmission electron microscopy and were loaded with Rhodamine B. Fluorescence studies revealed successful loading of the dye and changes in the salt or acid concentration unloaded the dye. SBA-type silica was densified while maintaining mesoporosity using spark plasma sintering and proof of principle were done to illustrate how these materials could be chemically modified into semiconductors relevant to energy applications

Identification of the niche and phenotype of the first human hematopoietic stem cells

SummaryIn various vertebrate species, the dorsal aorta (Ao) is the site of specification of adult hematopoietic stem cells (HSCs). It has been observed that the upregulation of essential hematopoietic transcription factors and the formation of specific intra-aortic hematopoietic cell clusters occur predominantly in the ventral domain of the Ao (AoV). In the mouse, the first HSCs emerge in the AoV. Here, we demonstrate that in the human embryo the first definitive HSCs also emerge asymmetrically and are localized to the AoV, which thus identifies a functional niche for developing human HSCs. Using magnetic cell separation and xenotransplantations, we show that the first human HSCs are CD34+VE-cadherin+CD45+C-KIT+THY-1+Endoglin+RUNX1+CD38−/loCD45RA−. This population harbors practically all committed hematopoietic progenitors and is underrepresented in the dorsal domain of the Ao (AoD) and urogenital ridges (UGRs). The present study provides a foundation for analysis of molecular mechanisms underpinning embryonic specification of human HSCs