Books in the Springer Theses series

The structure of quantum theory permits interference of indistinguishable paths. At the same time, however, it also limits such interference to certain orders and any higher-order interference is prohibited. This thesis develops and studies concepts to test quantum theory with higher-order interference using many-particle correlations, the latter being generally richer and typically more subtle than single-particle correlations. It is demonstrated that quantum theory in general allows for interference up to order 2M in M-particle correlations. Depending on the mutual coherence of the particles, however, the related interference hierarchy can terminate earlier. In this thesis, we show that mutually coherent particles can exhibit interference of the highest orders allowed. We further demonstrate that interference of mutually incoherent particles truncates already at order M+1, although interference of the latter is principally more multifaceted than their coherent counterpart. We introduce two families of many-particle Sorkin parameters, whose members are expected to be all zero when quantum mechanics holds. As proof of concept, we demonstrate the disparate vanishing of such higher-order interference terms as a function of coherence in experiments with mutually coherent and incoherent sources. Finally, we investigate the influence of exotic kinked or looped quantum paths, which are permitted by Feynman's path integral approach, in such setups.

This book reports a study of a class of Dion-Jacobson-type layered perovskite oxides in which high oxide-ion conductivities in phases were discovered for the first time in the world. The oxide-ion conductors are important in various energy conversion devices and environmental protection applications such as solid-oxide fuel cells, oxygen gas sensors, oxygen separation membranes, and oxygen-based catalysts. The discoveries are based on a new screening method, called the bond valence method, combined with an original design concept. The present finding of high oxide-ion conductivity reported in the thesis suggested the potential of Dion-Jacobson phases as a platform to identify superior oxide-ion conductors.To understand what causes such high oxide-ion conductivities in these layered perovskite oxides, the author analyzed their crystal structures at high temperature and described the relationship between oxide-ion conductivities and their crystal structures. A deep understanding of the mechanisms of oxide-ion diffusivity at an atomic level in the Dion-Jacobson phases is clarified.The discovery of these materials, the new screening method, and the original design concept make possible the realization of many environment-friendly technologies. The findings in this thesis facilitate the possibilities for many novel applications that will help lead to a sustainable future.

The thesis tackles two distinct problems of great interest in gravitational mechanics ¿ one relativistic and one Newtonian. The relativistic one is concerned with the "first law of binary mechanics", a remarkably simple variational relation that plays a crucial role in the modern understanding of the gravitational two-body problem, thereby contributing to the effort to detect gravitational-wave signals from binary systems of black holes and neutron stars. The work reported in the thesis provides a mathematically elegant extension of previous results to compact objects that carry spin angular momentum and quadrupolar deformations, which more accurately represent astrophysical bodies than mere point particles. The Newtonian problem is concerned with the isochrone problem of celestial mechanics, namely the determination of the set of radial potentials whose bounded orbits have a radial period independent of the angular momentum. The thesis solves this problem completely ina geometrical way and explores its consequence on a variety of levels, in particular with a complete characterisation of isochrone orbits. The thesis is exceptional in the breadth of its scope and achievements. It is clearly and eloquently written, makes excellent use of images, provides careful explanations of the concepts and calculations, and it conveys the author¿s personality in a way that is rare in scientific writing, while never sacrificing academic rigor.

This book presents the observation and the control of spin-polarized electrons in Rashba thin films and topological insulators, including the first observations of a weak topological insulator (WTI) and a higher-order topological insulator (HOTI) in bismuth halides. It begins with a general review of electronic structures at the solid surface and mentions that an electron spin at a surface is polarized due to the Rashba effect or topological insulator states with strong spin-orbit coupling. Subsequently it describes the experimental techniques used to study these effects, that is, angle-resolved photoemission spectroscopy (ARPES). Further it moves its focus onto the experimental investigations, in which mainly two different systems-noble metal thin films with the Rashba effects and bismuth halides topological insulators-are used. The study of the first system discusses the role of wavefunctions in spin-splitting and demonstrates a scaling law for the Rashba effect in quantum well films for the first time. High-resolution spin-resolved ARPES plays a vital role in systematically trace the thickness-evolution of the effect. The study of the latter material is the first experimental demonstration of both a WTI and HOTI state in bismuth iodide and bismuth bromide, respectively. Importantly, nano-ARPES with high spatial resolution is used to confirm the topological surface states on the side surface of the crystal, which is the hallmark of WTIs.The description of the basic and recently-developed ARPES technique with spin-resolution or spatial-resolution, essential in investigating spin-polarized electrons at a crystal surface, makes the book a valuable source for researchers not only in surface physics or topological materials but also in spintronics and other condensed-matter physics.

How planets form is one of the long-standing questions in astrophysics. In particular, formation scenarios of planetesimals which are kilometer-sized bodies and a precursor of planets are still unclear and under debate although some promising mechanisms have been proposed.This book highlight disk instabilities that have the potential to explain the origin of planetesimals. Using linear analyses and numerical simulations, it addresses how a disk evolves through the development of instabilities, and also presents a new instability driven by dust coagulation. As a result, the simulation demonstrates a scenario of planetesimal formation: A successive development of multiple instabilities triggers planetesimal formation in resulting dusty rings.

This book constructs a non-Bloch band theory and studies physics described by non-Hermitian Hamiltonian in terms of the theory proposed here.In non-Hermitian crystals, the author introduces the non-Bloch band theory which produces an energy spectrum in the limit of a large system size. The energy spectrum is then calculated from a generalized Brillouin zone for a complex Bloch wave number. While a generalized Brillouin zone becomes a unit circle on a complex plane in Hermitian systems, it becomes a circle with cusps in non-Hermitian systems. Such unique features of the generalized Brillouin zone realize remarkable phenomena peculiar in non-Hermitian systems. Further the author reveals rich aspects of non-Hermitian physics in terms of the non-Bloch band theory. First, a topological invariant defined by a generalized Brillouin zone implies the appearance of topological edge states. Second, a topological semimetal phase with exceptional points appears, The topological semimetal phase is unique to non-Hermitian systems because it is caused by the deformation of the generalized Brillouin zone by changes of system parameters. Third, the author reveals a certain relationship between the non-Bloch waves and non-Hermitian topology.

This book introduces readers to the preparation of metal nanocrystals and its applications. In this book, an important point highlighted is how to design noble metal nanocrystals at the atomic scale for energy conversion and storage. It also focuses on the controllable synthesis of water splitting electrode materials including anodic oxygen evolution reaction (OER) and cathode hydrogen evolution reaction (HER) at the atomic level by defect engineering and synergistic effect. In addition, in-situ technologies and theoretical calculations are utilized to reveal the catalytic mechanisms of catalysts under realistic operating condition. The findings presented not only enrich research in the nano-field, but also support the promotion of national and international cooperation.

This book investigates the physics of the discovered Higgs boson and additional Higgs bosons in the extended Higgs models which includes higher-order quantum corrections. While the 125 GeV Higgs boson was discovered, the structure of the Higgs sector is still a mystery. Since the Higgs sector determines the concrete realization of the Higgs mechanism, the study of its nature is one of the central interests in current and future high-energy physics. The book begins with a review of the standard model and the two-Higgs doublet model, which is one of the representatives of the extended Higgs models. Subsequently, we discuss the studies of the two-Higgs doublet model at the lowest order of perturbation. Following the lowest-order analysis, we study the higher-order electroweak corrections in Higgs physics. After reviewing the renormalization procedure and the higher-order corrections in the decays of the discovered Higgs boson, we discuss the higher-order corrections in theHiggs strahlung process from an electron-positron collision, the decays of the additional charged and CP-odd Higgs bosons in the two-Higgs doublet model. From the series of these studies, it is found that the nature of the Higgs sector can be widely investigated by future collider experiments.

This thesis presents a search for long-lived particles decaying into displaced electrons and/or muons with large impact parameters. This signature provides unique sensitivity to the production of theoretical lepton-partners, sleptons. These particles are a feature of supersymmetric theories, which seek to address unanswered questions in nature. The signature searched for in this thesis is difficult to identify, and in fact, this is the first time it has been probed at the Large Hadron Collider (LHC). It covers a long-standing gap in coverage of possible new physics signatures. This thesis describes the special reconstruction and identification algorithms used to select leptons with large impact parameters and the details of the background estimation. The results are consistent with background, so limits on slepton masses and lifetimes in this model are calculated at 95% CL, drastically improving on the previous best limits from the Large Electron Positron Collider (LEP).

This book offers construction of a renormalizable effective theory of electroweak-interacting spin-1 dark matter (DM). The effective theory realizes minimal but essential features of DM predicted in extra-dimension models, and enables to systematically treat non-perturbative corrections such as the Sommerfeld effects. Deriving an annihilation cross section including the Sommerfeld effects based on the effective theory, the author discusses the future sensitivity of observations to gamma-ray from the Galactic Center. As a result, the author explains the monochromatic gamma-ray signatures originate from two photons (¿¿) or photon and Z boson (¿Z) produced in the process of DM annihilations, and concludes a possible scenario that unstable neutral spin-1 particles (Z¿) appear and results in a spectral peak in addition to the one caused by ¿¿ and ¿Z channels in gamma-ray observations. If those two spectral peaks are observed, the masses of spin-1 DM and Z¿ would be reconstructed.

This thesis presents the first successful realization of a compact, low-noise, and few-cycle light source in the mid-infrared wavelength region. By developing the technology of pumping femtosecond chromium-doped II-VI laser oscillators directly with the emission of broad-stripe single-emitter laser diodes, coherent light was generated with exceptionally low amplitude noise ¿ crucial for numerous applications including spectroscopy at high sensitivities. Other key parameters of the oscillator's output, such as pulse duration and output power, matched and even surpassed previous state-of-the-art systems. As a demonstration of its unique capabilities, the oscillator's powerful output was used to drive ¿ without further amplification ¿ the nonlinear generation of coherent mid-infrared light spanning multiple octaves. The resulting table-top system uniquely combines high brilliance and ultrabroad spectral bandwidth in the important mid-infrared spectral range.The rapid development of this technology is comprehensively and lucidly documented in this PhD thesis. Together with a thorough review of literature and applications, and an extensive analysis of the theoretical foundations behind ultrafast laser oscillators, the thesis will serve as a valuable reference for the construction of a new generation of mid-infrared light sources.