1,339 research outputs found

    Selected problems of materials science. Vol. 2. Nano-dielectrics metals in electronics. Mеtamaterials. Multiferroics. Nano-magnetics

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    The textbook examines physical foundations and practical application of current electronics materials. Modern theories are presented, more important experimental data and specifications of basic materials necessary for practical application are given. Contemporary research in the field of microelectronics and nanophysics is taken into account, while special attention is paid to the influence of the internal structure on the physical properties of materials and the prospects for their use. English-language lectures and other classes on the subject of the book are held at Igor Sikorsky Kyiv Polytechnic Institute at the departments of “Applied Physics” and “Microelectronics” on the subject of materials science, which is necessary for students of higher educational institutions when performing scientific works. For master’s degree applicants in specialty 105 “Applied physics and nanomaterials”.Розглянуто фізичні основи та практичне застосування актуальних матеріалів електроніки. Подано сучасні теорії, наведено найважливіші експериментальні дані та специфікації основних матеріалів, які потрібні для практичного застосування. Враховано сучасні дослідження у галузі мікроелектроніки та нанофізики, при цьому особливу увагу приділено впливу внутрішньої структури на фізичні властивості матеріалів і на перспективи їх використання. Англомовні лекції та інші види занять за тематикою книги проводяться в КПІ ім. Ігоря Сікорського на кафедрах «Прикладна фізика» та «Мікро-електроніка» за напрямом матеріалознавство, що необхідно студентам вищих навчальних закладів при виконанні наукових робіт. Для здобувачів магістратури за спеціальністю 105 «Прикладна фізика та наноматеріали»

    Computational development of models and tools for the kinetic study of astrochemical gas-phase reactions

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    This PhD thesis focuses on the application and development of computational tools and methodologies for the modeling of the kinetics of gas-phase reactions of astrophysical interest in the interstellar medium (ISM). The complexity related to the investigation of chemical reactivity in space is mostly due to the extreme physical conditions of temperature, pressure and exposure to high-energy radiation, which in turn also lead to the formation of exotic species, like radicals and ions. Nevertheless, there is still much to be understood about the formation of molecules, the major issue being the lack of sufficient laboratory (experimental and computational) studies. A more detailed and accurate study of all the chemical processes occurring in the ISM will allow us to obtain the data necessary to simulate the chemical evolution of an interstellar cloud over time using kinetic models including thousands of reactions that involve hundreds of species. The collection of the kinetic parameters required for the relevant reactions has led to the growth of different astrochemical databases, such as KIDA and UMIST. However, the data gathered in these catalogues are incomplete, and rely extensively on crude estimations and extrapolations. These rates are of paramount importance to get a better comprehension of the relative abundances of the chemical compounds extrapolated by the astronomers from the spectral data recorded through the radio telescopes and the in-orbit devices, like the satellites. Accurate state-of-the-art computational approaches play a fundamental role in analyzing feasible reaction mechanisms and in accurately predicting the associated kinetics. Such approaches usually rely on chemical intuition where a by-hand search of the most likely pathways is performed. Unfortunately, thisprocedure can lead to overlook significant mechanisms, especially when large molecular systems are investigated. Increasing the size of a molecule can also increase the number of its possible conformers which can show a different chemical reactivity with respect to the same chemical partner. This brings to get very complex chemical reaction networks in which hundreds of chemical species are involved and thousands of chemical reactions can occur.During the last decades, a lot of effort has been done to develop computational techniques able to perform extensive and thorough investigations of complex reaction mechanisms. Such approaches rely on automated computational protocols which drastically decrease the risk of making blunders during the search for significant reaction pathways.Furthermore, the accurate characterization of the potential energy surfaces (PESs) critical points, like reactants, intermediates, transition states and products involved in the reaction mechanism, is crucial in order to carry out a reliable kinetic investigation. The kinetic analysis of an erroneous potential energy surface, would lead to gross errors in the estimation of the rate constants of the chemical species involved in the reaction.In order to avoid such errors, the combination of high-level electronic structure calculations via composite scheme can be helpful to get a more precise estimation of the energy barriers involved in the reaction mechanism. It has been proven that "cheap"[1] composite schemes can achieve subchemical accuracy without any empirical parameters and with convenient computation times, making them perfect for the purpose of this thesis.In recent decades, many efforts have been made to develop theoretical and computational methodologies to perform accurate numerical simulations of the kinetics of such complex reaction mechanisms in a wide range of thermodynamic conditions that mimic extreme reaction environmentsas for combustion systems, the atmosphere and the ISM. Such methodologies are based on the ab initio-transition-state-theory-based master equation approach, which allows the determination of rate coefficients and branching ratios of chemical species involved in complex chemical reactions. This methodology allows to make accurate predictions of the relative abundances of the reaction products for complex reactions even under conditions of temperature and pressure not experimentally accessible, such as those that characterize the ISM. Based on these premises, this dissertation has been focused on the application of a computational protocol for the ab initio-based computational modeling and kinetic investigation of gas-phase reactions which can occur in the ISM.This protocol is based on the application of validated methodologies for the automated discovery of complex reaction mechanisms by means of the AutoMeKin[2] program, the accurate calculation of the energetic of the potential energy surfaces (PESs) through the junChS and junChS-F12a "cheap" composite schemes and the kinetic investigation using the StarRate computer program specifically designed to study gas-phase reactions of astrochemical interest in conjunction with the MESS program. Furthermore, this dissertation has been also focused on the development and implementation of StarRate, a computer program for the accurate calculation of kinetics through a chemical master equation approach of multi-step chemical reactions. StarRate is an object-based program written in the so-called F language. It is structured in three main modules, namely molecules, steps and reactions, which extract the properties needed to calculate the kinetics for the single-step reactions partecipating in the overall reaction. Another module, in_out, handles program’s input and output operations. The main program,starrate, controls the sequences of the calling of the procedures contained in each of the three main modules.Through these modular structure, StarRate[3] can compute canonical and microcanonical rate coefficients taking into account for the tunneling effect and the energy-dependent and time-dependent evolution of the species concentrations involved in the reaction mechanism. Such protocol has been applied to investigate the formation reaction mechanisms of some complex interstellar polyatomic molecules, named interstellar complex organic molecules (iCOMs). More specifically, the formation of prebiotic iCOMs in space has raised considerable interest in the scientific community, because they are considered as precursors of more complex biological systems involved in the origin of life in the Universe. Debate on the origins of these biomolecular building blocks has been further stimulated by the discovery of nucleobases and amino acids in meteorites and other extraterrestrial sources. However, few insights on the chemistry which brings to the formation of such compounds is known.  References: [1] Jacopo Lupi,Silvia Alessandrini,Cristina Puzzarini,and Vincenzo Barone.junchs and junchs-F12 models:Parameter-free efficient yet accurate compositeschemes for energies and structures of noncovalent complexes. Journal of Chem-ical Theory and Computation, 17(11):6974–6992, 2021. PMID: 34677974.[2] Emilio Martínez-Núñez, George L. Barnes, David R. Glowacki, Sabine Kopec,Daniel Peláez, Aurelio Rodríguez, Roberto Rodríguez-Fernández, Robin J. Shan-non, James J. P. Stewart, Pablo G. Tahoces, and Saulo A. Vazquez.Au-tomekin2021: An open-source program for automated reaction discovery. Journalof Computational Chemistry, 42(28):2036–2048, 2021.[3] Surajit Nandi, Bernardo Ballotta, Sergio Rampino, and Vincenzo Barone.Ageneral user-friendly tool for kinetic calculations of multi-step reactions withinthe virtual multifrequency spectrometer project. Applied Sciences, 10(5), 2020

    Electron Thermal Runaway in Atmospheric Electrified Gases: a microscopic approach

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    Thesis elaborated from 2018 to 2023 at the Instituto de Astrofísica de Andalucía under the supervision of Alejandro Luque (Granada, Spain) and Nikolai Lehtinen (Bergen, Norway). This thesis presents a new database of atmospheric electron-molecule collision cross sections which was published separately under the DOI : With this new database and a new super-electron management algorithm which significantly enhances high-energy electron statistics at previously unresolved ratios, the thesis explores general facets of the electron thermal runaway process relevant to atmospheric discharges under various conditions of the temperature and gas composition as can be encountered in the wake and formation of discharge channels

    Microscopy of spin hydrodynamics and cooperative light scattering in atomic Hubbard systems

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    Wechselwirkungen zwischen quantenmechanischen Teilchen können zu kollektiven Phänomenen führen, deren Eigenschaften sich vom Verhalten einzelner Teilchen stark unterscheiden. Während solche Quanteneffekte im Allgemeinen schwierig zu beobachten sind, haben sich ultrakalte, in optischen Gittern gefangene atomare Gase als vielseitige experimentelle Plattform zur Erforschung der Quantenvielteilchenphysik erwiesen. In dieser Arbeit setzten wir ein Gitterplatz- und Einzelatom-aufgelöstes Quantengasmikroskop für bosonische Rb-87 Atome ein, um Vielteilchensysteme im und außerhalb des Gleichgewichts zu untersuchen. Zunächst betrachteten wir den quantenmechanischen Phasenübergang zwischen dem suprafluiden und dem Mott-isolierenden Zustand im Bose-Hubbard-Modell, das nativ durch kalte Atome in optischen Gittern realisiert wird, und zeigten, dass sich die Brane-Parität eignet, um nichtlokale Ordnung im konventionell als ungeordnet erachteten zweidimensionalen Mott-Isolator zu identifizieren. Mithilfe eines mikroskopischen Ansatzes zur Realisierung einstellbarer Gittergeometrien und programmierbarer Einheitszellen implementierten wir Quadrats-, Dreiecks-, Kagome- und Lieb-Gitter und beobachteten die Skalierung des Phasenübergangspunkts mit der mittleren Koordinationszahl des Gitters. In einem eindimensionalen Gitter untersuchten wir zudem den Hochtemperatur-Spintransport im Heisenberg-Modell, das durch Superaustausch in der Mott-isolierenden Phase eines zwei-Spezies Bose-Hubbard-Modells realisiert wurde. Durch Betrachten der Relaxationsdynamik eines als Domänenwand präparierten Anfangszustandes fanden wir eine superdiffusive Raum-Zeit-Skalierung mit einem anomalen dynamischen Exponenten von 3/2. Anschließend untersuchten wir die theoretisch vorhergesagten mikroskopischen Voraussetzungen für Superdiffusion, indem wir reguläre Diffusion im nicht-integrablen, zweidimensionalen Heisenberg-Modell und ballistischen Transport für SU(2)-Symmetrie-gebrochene magnetisierte Anfangszustände nachwiesen. Weiterhin maßen wir die Zählstatistik der durch die Domänenwand transportierten Spins; die sich daraus ergebende schiefe Verteilung deutete auf einen nichtlinearen zugrundeliegenden Transportprozess hin, der an die dynamische Kardar-Parisi-Zhang Universalitätsklasse erinnert. Mittels Mott-Isolatoren im Limit tiefer Gitter konnten wir darüber hinaus die durch Photonen vermittelten Wechselwirkungen in einem Spinsystem untersuchen, das aus zwei über einen geschlossenen optischen Übergang gekoppelten Zuständen besteht. Durch spektroskopische Untersuchung der Reflexion und Transmission konnten wir die direkte Anregung einer subradianten Eigenmode und kohärente Spiegelung beobachten, was auf die Realisierung einer effizienten, im freien Raum operierenden, paraxialen Licht-Materie-Schnittstelle hindeutet.The interplay of quantum particles can give rise to collective phenomena whose characteristics are distinct from the behavior of individual particles. While quantum effects are generally challenging to observe, ultracold atomic gases trapped in optical lattices have emerged as a versatile experimental platform to study quantum many-body physics. In this thesis, we employed a site– and single-atom–resolved quantum gas microscope of bosonic Rb-87 atoms to explore many-body systems in and out of equilibrium. We first considered the ground-state quantum phase transition between the superfluid and Mott-insulating state in the Bose–Hubbard model, natively realized by cold atoms in optical lattices, for which we found brane parity to be suitable for detecting nonlocal order in the conventionally unordered two-dimensional Mott insulator. Using a microscopic approach to realizing tunable lattice geometries and programmable unit cells, we implemented square, triangular, kagome and Lieb lattices, and observed the mean-field scaling of the phase transition point with average coordination number. In a one-dimensional lattice, we furthermore studied high-temperature spin transport in the Heisenberg model, realized by superexchange in the Mott-insulating phase of a two-species Bose–Hubbard model. By tracking the relaxation dynamics of an initial domain-wall state, we found superdiffusive space–time scaling with an anomalous dynamical exponent of 3/2. We then probed the predicted microscopic requirements for superdiffusion, verifying regular diffusion for the integrability-broken two-dimensional Heisenberg model and ballistic transport for SU(2)-symmetry–broken net magnetized initial states. Subsequently, we measured the full counting statistics of spins transported across the domain wall; the resulting skewed distribution implied a nonlinear underlying transport process, reminiscent of the Kardar–Parisi–Zhang dynamical universality class. Moving to Mott insulators in the deep-lattice limit, we could moreover study photon-mediated interactions on a subwavelength-spaced, array-ordered spin system consisting of states coupled by a closed optical transition. By spectroscopically probing the reflectance and transmittance, we demonstrated the direct excitation of a subradiant eigenmode and observed specular reflection, indicating the realization of an efficient free-space paraxial light–matter interface

    Neutron Scattering Investigations of Three-Dimensional Topological States

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    Topological magnets represent a unique class of quantum materials in which a nontrivial Berry curvature in real- or momentum-space couples to the magnetic properties of the topological electronic or spin system. Magnetic skyrmions constitute one such class of topological magnets, characterized by real space topological swirling spin-textures which manifest as localized nanometric excitations in the magnetization field. These protected quasi-particle objects possess a helical chiral structure which supports a diverse landscape of states and defects, whose interactions with spins and electrons produce novel transport properties and emergent dynamics controllable over a wide range of parameter space. This spectrum of phenomena has inspired magnetic skyrmions as the forerunners for novel spintronic high-density memory and ultra-low power logic device applications. As quasiparticles, skyrmions may condense into crystalline orders, typically forming periodic lattice arrangements which extend three-dimensionally in bulk materials. This enhanced dimensionality opens the door to new stabilization pathways, configurational degrees of freedom, and dynamical modes which offer unique functionalities to those of thin systems. For practical applications, understanding skyrmion nucleation, annihilation, transition, and organizational pathways is critical to realizing controllable dynamics and manipulation in future devices. In this thesis, we explore the development and application of various neutron scattering tomography and structured neutron beam techniques for three-dimensional investigations of bulk magnetic topological materials and their defect-mediated dynamical phenomena. A combination of X-ray, magnetometry, and neutron scattering techniques are used to first identify and characterize the disordered phase of an above room-temperature bulk skyrmion material, Co8Zn8Mn4. Detailed small angle neutron scattering (SANS) measurements are then performed over the entire temperature-magnetic field phase diagram of the material as a function of a dynamic skyrmion ordering sequence. 2D SANS images in combination with micromagnetic simulations reveal a novel disordered-to-ordered skyrmion square lattice transition pathway which represents a new type of non-charge conserving topological transition. This transition is characterized by a novel promotion of four-fold order in SANS and a violation of the conservation of total skyrmion number. Dynamical skyrmion responses in the metastable skyrmion triangular lattice phase showed an exotic memory phase, with an ordered skyrmion signal persisting in spite of hysteresis protocols involving field-induced saturation into the ferromagnetic phase. Further studies of skyrmion stabilization mechanisms and their dynamical defect pathways were performed through the development of a novel SANS tomography algorithm, applied to the ordered thermal equilibrium skyrmion triangular lattice phase of the bulk Co8Zn8Mn4 sample. Multi-projection neutron scattering datasets collected from the sample were used to generate the first three-dimensional visualizations of a bulk skyrmion lattice. The reconstructions unveiled a host of exotic skyrmion features, such as branching, segmented, twisting, and filament structures, mediated by three-dimensional topological transitions through two different emergent monopole (MP)-antimonopole (AMP) defect pathways. Methods for the direct identification and determination of topological features and defects of bulk micromagnetic materials, without a priori knowledge of the sample, can be achieved through the incorporation of structured neutron beam methods to neutron scattering experiments. Holographic approaches similar to those used in the development of optical structured waves were implemented with neutrons to generate a method for the selective tuning of single-valued neutron orbital angular momentum (OAM) states. A conventional SANS setup was used to explore the diffraction of linear neutron waves input on a microfabricated grating which consists of arrays of phase-gratings with q-fold fork dislocations and nanometric spatial dimensions comparable to those of magnetic skyrmion lattice periodicities. Far-field scattering images exhibit doughnut intensity profiles centered on the first diffraction orders, with q-dependent radii, thereby demonstrating the tunable generation of topological neutron states for phase- and topology-matched studies of quantum materials. Together, these studies demonstrate the development and application of novel tools for direct investigations of bulk topological magnetic materials, while uncovering a diverse collection of skyrmion energetics, disorder-dependent dynamics, and three-dimensional topological transition defect pathways. Future works are proposed which explore the threedimensional formation and evolution of bulk skyrmion tubes under various temperaturemagnetic field trajectories and degrees of skyrmion order, using both tomographic, structured neutron beam approaches, and combinations thereof. In doing so, we may provide the first standalone method of characterizing bulk magnetic sample topologies, defect densities, and their correlations. These methods open the door to a new generation of neutron scattering techniques for probing exotic topological interactions and the complete standalone characterization of quantum materials

    Undergraduate and Graduate Course Descriptions, 2023 Spring

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    Wright State University undergraduate and graduate course descriptions from Spring 2023

    NEGATIVE ION PHOTOELECTRON SPECTROSCOPY: ANTIOXIDANTS, ACTINIDE CLUSTERS, MOLECULAR ACTIVATION, AND SUPERATOMS

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    Negative ion photoelectron spectroscopy (PES) utilizes photons to examine the electronic and geometric properties of negative ions and their corresponding neutrals. A diverse range of topics spanning biology, chemistry, physics, and material science were investigated, including antioxidation abilities of antioxidants, electronic structure of actinide-containing clusters, mechanism of activation reactions, design of superatoms, multiple Rydberg anions, and electron induced proton transfer. The insight acquired from anion photoelectron spectroscopy has provided understanding into the above-mentioned topics at a molecular level. After briefly introducing the PES technique, Chapters II to VI present these studies in detail. In Chapter II, the antioxidation abilities of two famous antioxidants in the body and food, ascorbic acid and gallic acid, were measured spectroscopically and compared to computations. In Chapter III, we studied the interactions of hydrogen, oxygen, or gold atoms with thorium or uranium atoms; chemical bonding between thorium and thorium atoms in clusters; and electron affinity of the uranium atom. Chapter IV discusses the small molecule activation, such as water, carbon dioxide, methane, or hydroxylamine, by single metal anions or metal hydride anions. With the help of high-level quantum chemistry calculations, reaction mechanisms were revealed at a molecular level. Finally, Chapter V shows that the electronic spectra in cobalt sulfide superatomic clusters are tunable via ligand substitution, shedding light on novel material designs

    Brain Computations and Connectivity [2nd edition]

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    This is an open access title available under the terms of a CC BY-NC-ND 4.0 International licence. It is free to read on the Oxford Academic platform and offered as a free PDF download from OUP and selected open access locations. Brain Computations and Connectivity is about how the brain works. In order to understand this, it is essential to know what is computed by different brain systems; and how the computations are performed. The aim of this book is to elucidate what is computed in different brain systems; and to describe current biologically plausible computational approaches and models of how each of these brain systems computes. Understanding the brain in this way has enormous potential for understanding ourselves better in health and in disease. Potential applications of this understanding are to the treatment of the brain in disease; and to artificial intelligence which will benefit from knowledge of how the brain performs many of its extraordinarily impressive functions. This book is pioneering in taking this approach to brain function: to consider what is computed by many of our brain systems; and how it is computed, and updates by much new evidence including the connectivity of the human brain the earlier book: Rolls (2021) Brain Computations: What and How, Oxford University Press. Brain Computations and Connectivity will be of interest to all scientists interested in brain function and how the brain works, whether they are from neuroscience, or from medical sciences including neurology and psychiatry, or from the area of computational science including machine learning and artificial intelligence, or from areas such as theoretical physics

    Quantum effects, anomalies and renormalization in Electrodynamics, Cosmology and Black Holes

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    La Teoria Quàntica de Camps en Espais Corbats ha demostrat ser una teoria semi-clàssica molt útil per a l'estudi de fenòmens físics que combinen gravetat i efectes quàntics. En particular, prediu que la dinàmica d'un camp gravitacional de fons pot excitar espontàniament partícules a partir del buit quàntic. El procés de producció de partícules té una importància especial en l'estudi de l'univers primerenc en cosmologia i és la base de la radiació de Hawking en la física dels forats negres. Físicament, aquest efecte quàntic és anàleg a l'efecte Schwinger ben conegut en l'electrodinàmica quàntica. L'objectiu d'aquesta Tesi és estudiar aquest fenomen general de producció de partícules, així com altres aspectes fonamentals relacionats, com ara els efectes de “backreaction”, les anomalies quàntiques i les tècniques de renormalització. Una de les principals contribucions d'aquesta Tesi és el desenvolupament i la transferència de tècniques típicament utilitzades en la Teoria Quàntica de Camps en Espais Corbats a camps quàntics acoblats a “backgrounds” electromagnètics intensos. Per exemple, l'estudi inclou l'exploració de si l'anomalia gravitatòria per a camps de Weyl també està present en “backgrounds” elèctrics. A més, aquesta Tesi aborda si la propietat d’invariància adiabàtica del nombre de partícules creades en un univers en expansió es manté en el cas d'un background purament electromagnètic. Finalment, el mètode de renormalització adiabàtica, particularment útil per a camps quàntics en universos en expansió, es desenvolupa aquí per a camps de Dirac de 4 dimensions que estan acoblats a un background elèctric general. Aquesta Tesi també proporciona contribucions rellevants en l'àrea de la Gravitació. D'una banda, ampliem un mètode de regularització i renormalització reeixit que s'ha proposat recentment en la literatura, anomenat “pragmatic mode-sum method”. Aquest mètode es va desenvolupar originalment per a forats negres, i en aquesta Tesi l'hem adaptat per a universos en expansió. D'altra banda, la Tesi inclou un estudi detallat de les correccions quàntiques a la mètrica de Schwarzschild, originades pels efectes de “backreaction” dels camps quàntics que viuen en aquest “background”. L’argument conductor en l'anàlisi és l'anomalia conforme i la suposició d'estaticitat. També s'analitzen les propietats geomètriques i les aplicacions del nou espai-temps (sense horitzó). Tots aquests resultats milloren considerablement la nostra comprensió del comportament dels camps quàntics acoblats a “backgrounds” gravitacionals i electromagnètics externs. El paper de les anomalies quàntiques ha estat fonamental per aconseguir-ho.Quantum Field Theory in Curved Spacetimes has proven to be a very useful semiclassical theory for studying physical phenomena that combine gravity and quantum effects. In particular, it predicts that the dynamics of a background gravitational field can spontaneously excite particles out of the quantum vacuum. The process of particle production is of particular importance in the study of the very early universe in Cosmology, and it is the basis of Hawking radiation in black hole physics. Physically, this quantum effect is analogous to the well-known Schwinger effect in quantum electrodynamics. The goal of this Thesis is to study this general phenomenon of particle production, as well as other related fundamental aspects, such as backreaction effects, quantum anomalies, and renormalization techniques. One of the main contributions of this Thesis is the development and transfer of techniques typically used in QFT in curved spacetimes to quantum fields coupled to strong electrodynamics backgrounds. For instance, the study includes the exploration of whether the gravitational anomaly for Weyl fields is also present for electric backgrounds. Moreover, this Thesis also addresses if the fundamental property of the adiabatic invariance of the number of created particles in an expanding universe is maintained in the case of a pure electric background. Finally, the method of adiabatic renormalization, which is particularly useful for quantum fields in expanding universes, is developed here for 4-dimensional Dirac fields that are coupled to a general, electric background. This Thesis also provides relevant contributions in the area of Gravitation. On the one hand, we extend a successful regularization and renormalization method recently communicated in the literature, called pragmatic mode-sum regularization. This method was originally developed for black holes, and in this Thesis we adapted it for expanding universes. On the other hand, the Thesis includes a detailed study of quantum corrections to the Schwarzschild metric, originated from the back-reaction effects of quantum fields living in this black hole background. As we will see in more detail below, the driving argument in the analysis is the conformal anomaly and the assumption of staticity. The geometrical properties and applications of the new (horizonless) spacetime are also analyzed. All these results improve considerably our understanding of the behavior of quantum fields coupled to external gravitational and electromagnetic backgrounds. The role of quantum anomalies has been fundamental to achieve this

    Development and application of ab initio electron dynamics on traditional and quantum compute architectures

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    Electron dynamics processes are of utmost importance in chemistry. For example, light-induced processes are used in the field of photocatalysis to generate a wide variety of products by charge transfer, bond breaking, or electron solvation. Also in the field of materials science, more and more such processes are known and utilized, for example, to design more efficient solar cells. Even the formation of bonds in molecules is an electron dynamics process. Through experimental progress, it is now even possible to trigger specific processes and chemical reactions with special laser pulses. To study all these processes, computer-aided simulations are an indispensable tool. Depending on the size of the molecules considered and the desired accuracy, however, the underlying quantum-mechanical properties result in numerical formulas whose computation far exceeds the capabilities of even modern supercomputers. In this thesis, three projects are presented to demonstrate modern use cases of electron dynamics and show how recent developments in computer technology and software design can be used to develop more efficient and user-friendly programs. In the first project, the inter-Coulombic decay (ICD), an ultrafast energy transfer process, between two isolated chemical structures is investigated. After the excitation of one structure, the energy is transferred to the other, which is ionized as a result. The process has already been shown experimentally in atoms and molecules and is studied here for quantum dots, focusing on systems with more quantum dots and higher dimensions for the continuum than in previous studies. These elaborate studies are made possible by implementing computationally intensive program parts of the Heidelberg MCTDH program used on graphics processing units (GPUs). The performed studies show how the ICD process behaves with multiple partners as well as which competing decay processes occur and thus provide relevant information for the development of technologies based on quantum dots such as quantum dot qubits for use in quantum computers. Electron dynamics processes are not only relevant in the development of new quantum computers, but conversely, quantum computers can also provide the ability to perform electron dynamics with significantly more interacting electrons and a smaller error than it would ever be possible with traditional computers. In another project, therefore, a quantum algorithm was developed that could enable such simulations and their analysis in the future. The quantum algorithm was implemented in the dynamics program Jellyfish, which was also developed in the context of this dissertation. The program is based on a graphical user interface oriented on dataflow programming, which simultaneously leads to a modular structure. The resulting modules can be combined flexibly, which allows Jellyfish to be used for a wide variety of applications. In addition to dynamic algorithms, novel analysis methods were developed and demonstrated on laser-driven electronic excitations in molecules such as hydrogen, lithium cyanide, or guanine. Thus, the generation of electronic wave packets as well as transitions between electronic states were studied in an explicitly time-dependent manner and the formation of the exciton in such processes was described qualitatively by means of densities as well as quantitatively by so-called exciton descriptors such as exciton size or hole and particle position. Thus, in summary, this dissertation presents both new insights into electron dynamic processes and new possibilities for more efficient simulation of these processes using GPU implementations and quantum algorithms. The developed dynamics program Jellyfish offers the potential to be used in many further studies in this area and to be extended to allow for example simulations with a continuum like in the ICD calculations in the future
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