Springer Theses

This book provides important insights into the combustion behavior of novel energy crops and agricultural fuels. It describes a new experimental approach to combustion evaluation, involving fundamental, bench-scale and commercial-scale studies. The studies presented were conducted on two representative biomass energy crops: a woody biomass poplar (Populus sp. or poplar) and an herbaceous biomass brassica (Brassica carinata or brassica). Moreover, agricultural residues of Manihot esculenta or cassava were also analyzed. The main accomplishments of this work are threefold. Firstly, it offers an extensive characterization of the above-mentioned fuels, their ash chemistry and their emissions of both solid particles and gaseous compounds that form at typical grate combustion conditions. Secondly, it presents an in-depth analysis of ash fractionation processes for major ash species. Thirdly, it describes the role of some critical and volatile key elements (K, Cl, S and P) in grate-fired combustion systems and elucidates the main differences in the ash chemistry during combustion of Si-rich and P-rich fuels. All in all, this work provides novel insights on the basic and fundamental mechanisms of biomass grate combustion with a special focus on ash transformation and highlights important issues and recommendations that need to be considered for an appropriate conversion of ash-rich fuels and for the development of future technology in the context of both small- and medium-scale biomass-based heat and power production.

The thesis gives the first experimental demonstration of a new quantum bit (“qubit”) that fuses two promising physical implementations for the storage and manipulation of quantum information – the electromagnetic modes of superconducting circuits, and the spins of electrons trapped in semiconductor quantum dots – and has the potential to inherit beneficial aspects of both. This new qubit consists of the spin of an individual superconducting quasiparticle trapped in a Josephson junction made from a semiconductor nanowire. Due to spin-orbit coupling in the nanowire, the supercurrent flowing through the nanowire depends on the quasiparticle spin state. This thesis shows how to harness this spin-dependent supercurrent to achieve both spin detection and coherent spin manipulation. This thesis also represents a significant advancement to our understanding and control of Andreev levels and thus of superconductivity. Andreev levels, microscopic fermionic modes that exist in all Josephson junctions, are the microscopic origin of the famous Josephson effect, and are also the parent states of Majorana modes in the nanowire junctions investigated in this thesis. The results in this thesis are therefore crucial for the development of Majorana-based topological information processing.

This thesis makes significant advances in the use of microspheres in optical traps as highly precise sensing platforms. While optically trapped microspheres have recently proven their dominance in aqueous and vacuum environments, achieving state-of-the-art measurements of miniscule forces and torques, their sensitivity to perturbations in air has remained relatively unexplored. This thesis shows that, by uniquely operating in air and measuring its thermally-fluctuating instantaneous velocity, an optically trapped microsphere is an ultra-sensitive probe of both mass and sound. The mass of the microsphere is determined with similar accuracy to competitive methods but in a fraction of the measurement time and all while maintaining thermal equilibrium, unlike alternative methods. As an acoustic transducer, the air-based microsphere is uniquely sensitive to the velocity of sound, as opposed to the pressure measured by a traditional microphone. By comparison to state-of-the-art commercially-available velocity and pressure sensors, including the world’s smallest measurement microphone, the microsphere sensing modality is shown to be both accurate and to have superior sensitivity at high frequencies. Applications for such high-frequency acoustic sensing include dosage monitoring in proton therapy for cancer and event discrimination in bubble chamber searches for dark matter. In addition to reporting these scientific results, the thesis is pedagogically organized to present the relevant history, theory, and technology in a straightforward way.

This book presents a comprehensive exploration of unresolved mysteries in particle physics, delving into cutting-edge research aimed at unraveling the enigmatic facets of the Standard Model (SM). It tackles fundamental questions surrounding neutrino masses, flavor physics, and the strong CP problem, shedding light on the universe's underlying structure. The insightful analysis takes readers on a journey that begins with probing the mechanisms behind neutrino mass generation, including the existence of heavy neutral leptons and their implications for collider experiments. The book then navigates the intricate landscape of flavor physics, elucidating rare B-meson decays and their role as a window to new physics beyond the SM. Additionally, it investigates axions as potential hot dark matter candidates, offering valuable insights into their interactions with pions and cosmological implications. This work not only addresses current theoretical puzzles but also paves the way for future advancements in particle physics. Aimed at researchers, graduate students, and professionals in the field, this book serves as an indispensable resource for those seeking to delve deeper into the forefront of particle physics research. 

This book proposes innovative and timely modeling, as well as simulation strategies based on tensor networks, to tackle the difficult problem of describing the dynamics of open quantum systems at the molecular or nanometer scale beyond a Markovian treatment. Among the many insights it delivers, the work includes calculations of the dynamics of a quantum system coupled to a bosonic environment that can be potentially structured and/or possess spatial correlations. The relevance of these strategies is exemplified with the analysis of complex bio-inspired nanodevices. Researchers in the field will find here a clear and reliable contribution to the understanding of open quantum systems in a still little-explored regime where the reservoirs are no longer considered as simple baths but as sub-systems treated on an equal footing with the reduced system of interest. Moreover, the author discusses how to handle the situation of a system coupled to multiple baths. This is a very important and generic scenario, crucial, for instance, when discussing non-equilibrium steady states.