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The thesis reports on experiments conducted at a beamline combining a high-order harmonic generation-based attosecond pulse source operating at 100 kHz with an electron-ion coincidence detector (Reaction Microscope). The beamline is driven by a noncollinear optical parametric chirped pulse amplification system, in which few-cycle near infrared pulses generated by a titanium sapphire oscillator are amplified using the picosecond laser pulses delivered by a ytterbium-YAG pump laser. The reported beamline is designed for extreme ultraviolet–near infrared pump-probe experiments either with attosecond pulse trains or isolated attosecond pulses. A series of time-resolved measurements with attosecond pulse trains were performed in molecular nitrogen focusing on the predissociative ionic C state. The corresponding ultrafast photoelectron dynamics was accessed with vibrational resolution. The performed investigation revealed a non-trivial energy dependence of extracted photoionization delays with respect to a noble gas reference. The observed effect could be a consequence of the multi-electron character of the photoinduced process under investigation. The reported results are manifesting one more step towards the attosecond spectroscopy of large complex molecules with coincidence detection.

Over the past two decades, ideas coming from quantum information science have become increasingly relevant in high-energy physics. This is particularly evident in an area of quantum gravity called holography, also known as the AdS/CFT correspondence, where two concepts which have led to novel insights are entanglement and complexity. Particularly compelling open problems in our understanding of these quantities include the time-dependence of complexity and the interplay between complexity and entanglement both in non-equilibrium systems and for mixed states in quantum field theories (QFTs). In this talk, we explore these problems in scenarios which allow us to make tractable computations and extract universal properties of these quantities. We first study the time-dependence of complexity in a free scalar theory undergoing a quench through a critical point, finding evidence for universal scaling behaviour. We then study generalizations of complexity and entanglement entropy to mixed states and study their universal properties, finding qualitative agreement with holographic expectations. Finally, we identify the long-distance behaviour of correlations in mixed states as an interesting limit and explores its properties, leading to a novel prediction across all conformal field theories with a gap in the operator spectrum. Collectively, these findings set the stage for a better understanding of complexity and entanglement in QFTs. This is paramount for elucidating the mechanism which connects gravity and quantum theories in holography. Consequently, we believe that our results can lead to a better understanding of quantum gravity and quite possibly to new tools in the study of quantum many-body systems.

Quantum thermodynamics is a blossoming research program that uses tools and ideas from quantum information theory to extend the laws of thermodynamics to the domain of systems to which the laws of quantum mechanics apply and the thermodynamic limit does not necessarily apply. The contributions of this program are both foundational, in providing an approach to constructively derive the laws of phenomenological thermodynamics from the postulates of unitary quantum mechanics in a rigorous and bottom-up fashion, but also prac- tical, in providing the theory for an increasing number of experiments that attempt to build thermodynamic machines at scales that were previously inaccessible. One key mathematical tool used in quantum thermodynamics is the framework of resource theories, specifically the resource theory of thermal operations, in which the thermodynamic interaction of a system with a heat bath and various additional components such as work batteries, clocks or catalysts are modeled. In this cumulative thesis, various extensions and modifications of this framework are studied in order to derive novel results and insights about the possible thermodynamic evolution of quantum systems. In particular, following a system- atic exposition of the resource theory of thermal operations from first principles, I develop answers to the following questions: i) What is the smallest heat bath required to provide the necessary randomness for a system to undergo a given stochastic or thermodynamical evolution? ii) Does this size differ depending on whether the interaction between bath and system is quantum or classical? iii) How can quantum systems thermodynamically evolve in the presence of catalytic bystander systems and how can this be put to use? iv) What are the thermodynamic state transitions that an agent can operationally affect when she only has access to partial information about the underlying states of system and bath? v) How can we understand the emergence of the canonical ensemble in statistical thermodynamics from quantum mechanics? These questions cover a wide ground, but it will become clear that they can in fact all be discussed using the same formal tools. As such, the answers to the above questions provided in this thesis are both interesting in their own right — showing for example that there exists a gap in how efficiently randomness can be exploited quantumly as compared to classically or that catalytic bystander systems can be used to extract finite amounts of work per particle from macroscopic systems with non-vanishing probability — as well as illustrate the power of quantum thermodynamics as a set of tools to connect quantum mechanics and the theory of thermodynamics more generally., Quantenthermodynamik ist ein relativ junges und wachsendes Forchungsfeld, in dem Methoden und Konzepte aus der Quanteninformationstheorie verwendet werden um die Gesetzmäßigkeiten der Thermodynamik für kleine Quanten-Systeme zu studieren, auf die der thermodynamische Grenzfall nicht notwendigerweise Anwendung findet. Sie trägt hiermit bei sowohl zu den Grundlagen der Thermodynamik, indem sie die Gesetze der phenomenologischen Thermodynamik konstruktiv und “bottom-up” auf der Basis der Postulate der Quan- tenmechanik herleitet, als auch zur Praxis, indem sie die theoretischen Grundlagen für eine immer größere Menge an Experimenten liefert, in denen thermodynamische Maschinen gebaut werden, für deren adequate Beschreibung Quantenmechanik vonnöten ist. Ein zentrales mathematisches Werkzeug der Quantenthermodynamik sind sogenannte Ressourcentheorien, insbesondere die Ressourcentheorie der thermal operations, in welcher die thermodynamische Wechselwirking eines Systems mit einem Wärmebad und weiteren Systemen wie Batterien, Uhren und Katalysatoren modelliert wird. In dieser kumulativen Dissertation werden verschiedene Erweiterungen und Modifikationen dieses Modells eingeführt, auf deren Basis neue Ergebnisse bezüglich der möglichen thermodynamischen Evolution von Quantensystemen hergeleitet werden. Konkret werden, nach einer systematischen Einfüh- rung in die Ressourcentheorie der thermal operations, Antworten auf die folgenden Fragen entwickelt: i) Wie groß muss ein Wärmebad mindestens sein, damit ein System einen gegebenen stochastischen oder thermodynamischen Prozess durchalufen kann? ii) Hängt die Antwort auf Frage i) davon ab, ob die Interaktion zwischen Bad und System quantisch oder klassisch ist? iii) Welche thermodynamischen Zustandsänderungen eines System sind möglich in der Wechselwirkung mit katalytischen Hilfs-Systemen? iv) Welche Zustandsübergänge können operational erwirkt werden, wenn die zugrundeliegenden Mikrozustände von Bad und Sys- tem nur teilweise bekannt sind? v) Wie können wir den empirischen Erfolg des kanonischen Ensembles als Beschreibung von Systemen im thermodynamischen Gleichgewicht verstehen? Diese Fragen mögen sehr unterschiedlich erscheinen, aber es wird klar werden, dass sie alle mithilfe der gleichen mathematischen Werkzeuge behandelt werden können. Somit sind die Ergebnisse, die hier präsentiert werden, nicht nur interessant für sich genommen — es wird etwa gezeigt, dass quantische Zufallsprozesse strikt mächtiger sein können als ihre klassichen Gegenstücke existieren, oder dass mithilfe von Katalysatoren extensive Mengen an Arbeit von makroskopischen Systemen im thermischen Gleichgewicht mit nicht-verschwindender Wahrscheinlichkeit extrahiert werden können —, sondern sie illustrieren auch die Breite der Anwendbarkeit der Methoden der Quantenthermodynamik als Bindeglied zwischen Quantenmechanik und Thermodynamik.

R2-like ligand-binding oxidases (R2lox) assemble a heterodinuclear Mn/Fe cofactor which performs reductive dioxygen (O2) activation, catalyzes formation of a tyrosine–valine ether cross-link in the protein scaffold, and binds a fatty acid in a putative substrate channel. We have previously shown that the N-terminal metal binding site 1 is unspecific for manganese or iron in the absence of O2, but prefers manganese in the presence of O2, whereas the C-terminal site 2 is specific for iron. Here, we analyze the effects of amino acid exchanges in the cofactor environment on cofactor assembly and metalation specificity using X-ray crystallography, X-ray absorption spectroscopy, and metal quantification. We find that exchange of either the cross-linking tyrosine or the valine, regardless of whether the mutation still allows cross-link formation or not, results in unspecific manganese or iron binding at site 1 both in the absence or presence of O2, while site 2 still prefers iron as in the wild-type. In contrast, a mutation that blocks binding of the fatty acid does not affect the metal specificity of either site under anoxic or aerobic conditions, and cross-link formation is still observed. All variants assemble a dinuclear trivalent metal cofactor in the aerobic resting state, independently of cross-link formation. These findings imply that the cross-link residues are required to achieve the preference for manganese in site 1 in the presence of O2. The metalation specificity, therefore, appears to be established during the redox reactions leading to cross-link formation. Electronic supplementary material The online version of this article (10.1007/s00775-019-01639-4) contains supplementary material, which is available to authorized users.

The addition of graphitic fibers and flakes as fillers is commonly used to control the thermal expansion of metals. Sintered metal matrix composites with a planar distribution of graphite flakes show a low or negative thermal expansion coefficient perpendicular to the orientation plane of the graphite (z-CTE). Since the metal matrix has a positive isotropic expansion and graphite has a high z-CTE, this effect cannot be explained by a simple model of stapled metal–graphite layers. Instead, a mechanical interaction between graphite and matrix must be considered. With neutron scattering measurements, we show that there is little or no strain of the graphite flakes caused by the matrix, which can be explained by the high modulus of graphite. Instead, we suggest that a macroscopic crumpling of the flakes is responsible for the low z-CTE of the composite. The crumpled flakes are thicker at low temperature and get stretched and flattened by the expanding matrix at high temperature, explaining the reduction in the thermal expansion across the orientation plane.

The ability of classical thermodynamics to predict phenomena using only handful of parameters is miraculous. Moreover, this framework contrasts with other theories with its ability to describe our day to day experience, i. e. we know intuitively that an ice cube melts in a cold beverage on a hot summer day. A similarly powerful yet significantly less intuitive theory is quantum mechanics which describes the world at its tiniest length scales. Given this foundational position, we would expect to be able to derive all physical theories from quantum mechanics only. Unfortunately this would require knowing the quantum state of all particles which is costly as quantum mechanics requires resources growing exponentially in the system size to describe even relatively innocent many-body systems. Given this uncontrollable growth of parameters, it is highly desirable to apply the principles of thermodynamics to quantum many-body systems as a means to describe them ef- ficiently. Yet, the two theories are not obviously compatible. Subtle differences such as the definition of thermalisation already puzzled founding fathers like John von Neumann. While these have been understood by now, the focus shifted to gaining a thorough understanding of the process of thermalisation in the quantum regime, meaning that the state of the system can be described by a thermal ensemble locally after an initial out-of-equilibrium situation. In the recent past the field of quantum thermodynamics and specifically out-of-equilibrium dynamics has witnessed many successes notably the advent of highly controllable analogue quantum simulators which allow to probe out-of-equilibrium physics to an unprecedented precision. It has been established that thermalisation takes place in quantum many-body systems, but the underlying reasons and a comprehensive theory are still elusive. Only very recently, a class of systems exhibiting many-body localisation has been identi ed that defy this paradigm of thermalisation by localising their constituent particles despite many-body interactions. This can be captured using an effective description in terms of local constants of motion. Understanding the emergence of these physically relevant operators that hinder thermalisation hopefully sheds light also on the mechanism of thermalisation itself. In this thesis, we investigate the relation between thermodynamics and quantum mechanics in the context of out-of-equilibrium physics for many-body localisation. We give numerical evidence for the stability of localisation in large, closed onedimensional chains. Furthermore, we connect the established phenomenology of many-body localisation to experiments with ultra-cold atoms in optical lattices and give a blue print of measurements that can be performed with existing technology to show that the simulator indeed exhibits many-body localisation. We then set out to obtain a deeper understanding of the underlying theory of many-body localisation by devising an algorithm that explicitly constructs exact constants of motion allowing us to put the existing theoretical framework of many-body localisation to the test. It is our firm belief that understanding local constants of motion is indispensable to not only understand thermalisation in quantum many-body systems but is also of great use in other fields. A connection of this type is displayed by an extension of our algorithm to finding edge modes in spin chains with symmetry protected order., Klassische Thermodynamik erlaubt erstaunlich genaue Vorhersagen für physikalische Systeme basierend auf nur einer handvoll von Parametern. Darüber hinaus beschreibt sie ebenfalls unsere Alltagserfahrungen, beispielsweise einen schmelzenden Eiswürfel in einem kalten Getränk an einem heißen Sommertag. Eine vergleichbar mächtige, aber deutlich weniger intuitive Theorie ist die Quantenmechanik, die unsere Welt im Kleinen beschreibt und von vielen für die grundlegende Theorie gehalten wird. Es kommt uns jedoch teuer zu stehen, alle Details zu kennen, da die Zahl der Parameter die nötig sind, im ein Quantensystem zu beschreiben, exponentiell in dessen Größe wächst. Dies stellt bereits für verhältnismäßig kleine Quantensysteme ein großes Problem dar. Eine Lösung könnte darin liegen, die Prinzipien der Thermodynamik zu nutzen, um auch Quantensysteme effizient beschreiben zu können. Leider sind die beiden Theorien nicht auf Anhieb kompatibel. Kleinere Feinheiten, wie die Definition von Thermalisierung beschäftigten schon Gründungsväter wie John von Neumann, sind heutzutage aber gut verstanden. Unklar ist allerdings, wie ein Quantensystem nach einer initialen Störung einen lokal thermisch aussehenden Zustand erreicht. In der näheren Vergangenheit konnte das Feld der Quantenthermodynamik und insbesondere das der Nichtgleichgewichtsdynamik viele Erfolge feiern, insbesondere die Etablierung von Quantensimulatoren, die es erlauben Nichtgleichgewichtsphysik mit bisher unerreichter Präzision zu untersuchen. Es gilt als gesichert, dass Thermalisierung in Quantensystemen stattfindet, aber die Gründe oder eine umfassende Theorie dafür sind noch unbekannt. Vielteilchenlokalisierung beschreibt eine neue Klasse von Systemen, die dieser Beobachtung widersprechend nicht thermalisieren, indem Teilchen in einem solchen System lokalisiert werden und dies obwohl das System wechselwirkend ist. Daher können diese Systeme durch lokale Konstanten der Bewegung beschrieben werden. Ein tiefergehendes Verständnis warum diese Operatoren in solchen Systemen auftauchen wird hoffentlich auch einen Beitrag zur Frage leisten, wie Thermalisierung in Quantensystemen eigentlich zustande kommt. In dieser Doktorarbeit bringen wir Thermodynamik und Quantenmechanik einen kleinen Schritt näher zusammen. Wir legen unseren Fokus auf Nichtgleichgewichtsdynamik in Systemen mit Vielteilchenlokalisierung. Wir präsentieren numerische Resultate, die nahelegen, dass Vielteilchenlokalisierung in großen, geschlossenen, eindimensionalen Ketten stabil ist. Darüber hinaus bringen wir bekannte Effekte der Vielteilchenlokalisierung mit ultrakalten Atomen in optischen Gittern in Verbindung, indem wir skizzieren, wie man mit vorhandenen Techniken Vielteilchenlokalisierung in diesem Quantensimulator nachweist. Daraufhin wollen wir ein tieferes Verständnis für Vielteilchenlokalisierung erlangen, indem wir einen Algorithmus entwickeln, der exakte Konstanten der Bewegung konstruiert, anhand derer wir die Vorhersagen für Vielteilchenlokaliserung testen können. Wir glauben fest daran, dass es unausweichlich ist, lokale Konstanten der Bewegung zu verstehen, um Thermalisierung zu erklären, aber darüber hinaus auch weitere physikalische Effekte zugänglich zu machen. Wir schließen mit einer Anwendung einer Erweiterung unseres Algorithmus’ für Spinketten mit symmetriegeschützter Ordnung, in der wir deren Randmoden konstruieren.

International audience; Light materials with high thermal conductivity and low thermal expansion have a wide application potential for the thermal management of high-performance electronics, in particular in mobile and aerospace applications. We present here metal matrix composites with a mixture of graphite flakes and pitch-based carbon fibres as filler. The production by spark plasma sintering orients the filler particles on to a plane perpendicular to the pressing axis. The obtained materials have lower density than aluminium combined with a thermal conductivity significantly outperforming the used metal matrix. Depending on the ratio of the filler components, a low thermal expansion along the pressing direction (high graphite flakes content) or across the pressing direction (high carbon fibre content) is achieved. For a 1:3 ratio of carbon fibres to graphite, we measured an isotropic reduction of the thermal expansion of the matrix by up to 55%. We present a detailed characterisation of composites with two aluminium alloys as matrix and an overview of the properties for six different metal matrices including magnesium and copper. With the goal of a technical application, we show that the described properties are intrinsic to the material compositions and are achieved with a wide spectrum of production methods.

We report on fluorescence contrast improvement by using phase, amplitude, and polarization shaped laser pulses. The measurements were conducted by applying phase functions at different spectral amplitudes for excitations of dyes and agree very well with calculations. In particular, undesired one-photon excitations are circumvented with phase and amplitude tailored pulses for two-photon transition. This is realized by cutting out the laser spectrum at the wavelength of the one-photon process while utilizing an antisymmetric phase function that allows for constructive interference of the remaining outer spectral contributions for two-photon absorption. Moreover, polarization enhanced contrast between dyes is demonstrated where the two-photon dye is predominantly excited in one polarization direction and simultaneously the one-photon dye in the other polarization direction. The presented methods of shaping ultrashort laser pulses have a high potential for imaging applications.

Light can be used to modify and control properties of media, as in the case of electromagnetically induced transparency or, more recently, for the generation of slow light or bright coherent XUV and X-ray radiation. Particularly unusual states of matter can be created by light fields with strengths comparable to the Coulomb field that binds valence electrons in atoms, leading to nearly-free electrons oscillating in the laser field and yet still loosely bound to the core [1,2]. These are known as Kramers-Henneberger states [3], a specific example of laser-dressed states [2]. Here, we demonstrate that these states arise not only in isolated atoms [4,5], but also in rare gases, at and above atmospheric pressure, where they can act as a gain medium during laser filamentation. Using shaped laser pulses, gain in these states is achieved within just a few cycles of the guided field. The corresponding lasing emission is a signature of population inversion in these states and of their stability against ionization. Our work demonstrates that these unusual states of neutral atoms can be exploited to create a general ultrafast gain mechanism during laser filamentation., Comment: 9 pages, 4 figures, 10 pages supplementary material, 8 supplementary figures

In large-scale, hydrogen production from water-splitting represents the most promising solution for a clean, recyclable, and low-cost energy source. The realization of viable technological solutions requires suitable efficient electrochemical catalysts with low overpotentials and long-term stability for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) based on cheap and nontoxic materials. Herein, we present a unique molecular approach to monodispersed, ultra-small, and superiorly active iron phosphide (FeP) electrocatalysts for bifunctional OER, HER, and overall water-splitting. They result from transformation of a molecular iron phosphide precursor, containing a [Fe2P3] core with mixed-valence FeIIFeIII sites bridged by an asymmetric cyclo-P(2+1)3− ligand. The as-synthesized FeP nanoparticles act as long-lasting electrocatalysts for OER and HER with low overpotential and high current densities that render them one of the best-performing electrocatalysts hitherto known. The fabricated alkaline electrolyzer delivered low cell voltage with durability over weeks, representing an attractive catalyst for large-scale water-splitting technologies., Chemical Science, 9 (45), ISSN:2041-6520, ISSN:2041-6539

The thin film properties of tin(II) 2,3-naphthalocyanine (SnNPc) were interrogated and various strategies for controlling the crystallinity and crystalline orientation within the films were assessed. SnNPc is shown to crystallize in the space group P21/c (Z = 4), where the molecular arrangement consists of alternating layers of concave and convex overlap, induced by the out-of-plane Sn atoms, resulting in a 3D slipped-π-stack network structure analogous to that reported for Phase I of titanyl phthalocyanine. The thin films were studied by X-ray diffraction, atomic force microscopy and absorption spectroscopy and are highly sensitive not just to the conditions during growth, but also to substrate pre- and post-deposition treatment. While the films grown at room temperature were largely amorphous, the crystallinity was enhanced with substrate temperature, with the molecules orienting in a standing molecular geometry. A thin layer of 3,4:9,10-perlenetetracarboxylic dianhydride induces a lying molecular geometry of the same polymorph as that of the single crystal, while different polymorphs are accessible through solvent vapor annealing of amorphous films. Transient photocurrent measurements showed a dramatic improvement in photodetector device bandwidth for the lying molecular geometry, which was attributed to enhanced photoconductivity along the π-stacking axis, while solvent vapor annealing could be used to tune the photosensitivity across the near-infrared region.

The local efficiency of lamellar shaped Cu(In,Ga)Se2 solar cells has been investigated using scanning near‐field optical microscopy (SNOM). Topographic and photocurrent measurements have been performed simultaneously with a 100 nm tip aperture. The lamellar shaped solar cell with monolithic interconnects (P scribe) has been investigated on a nanometre scale for the first time at different regions using SNOM. It was found that, the cell region between P1 and P2 significantly contributes to the solar cells overall photocurrent generation. The photocurrent produced depends locally on the sample topography and it is concluded that it is mainly due to roughness changes of the ZnO:Al/i‐ZnO top electrode. Regions lying under large grains of ZnO produce significantly less current than regions under small granules. The observed photocurrent features were allocated primarily to the ZnO:Al/i‐ZnO top electrode. They were found to be independent of the wavelength of the light used (532 nm and 633 nm).

Indium islands on molybdenum coated glass can be grown in ordered arrays by surface structuring using a femtosecond laser. The effect of varying the molybdenum coated glass substrate temperature and the indium deposition rate on island areal density, volume and geometry is investigated and evaluated in a physical vapor deposition (PVD) process. The joined impact of growth conditions and spacing of the femtosecond laser structured spots on the arrangement and morphology of indium islands is demonstrated. The results yield a deeper understanding of the island growth and its precise adjustment to industrial requirements, which is indispensable for a technological application of such structures at a high throughput, for instance as precursors for the preparation of Cu(In,Ga)Se ₂ micro concentrator solar cells.

The development of simple to prepare, polarization-sensitive plasmonic apertures with two plasmonic modes, is described. To achieve these results, monocrystalline nanosphere lithography masks of 438 nm polystyrene spheres are modified with reactive ion etching before silver is subsequently evaporated through the mask at varied angles. As the angle of evaporation increases, round apertures, elliptical apertures or lines with bow-tie like features between two lines are produced. A primary plasmon mode is shown at 570 nm, while a tunable plasmon mode is demonstrated between 700 nm and 900 nm. Finite-difference time-domain calculations agree with the observed results and predict that this method of fabrication can produce tunable plasmonic features throughout the NIR optical telecommunication wavelength range. Lastly, the excitation polarization angle is compared with that of plasmonic nanorods and asymmetric nano-apertures systems to describe why the excitation polarization of the low energy mode is orthogonal to the long axis of the apertures. (© 2016 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim)