Electron-nuclear correlation, singly-excited Rydberg states and electron emission asymmetry in multiphoton ionization of H2

In this thesis multiphoton ionization of molecular hydrogen is investigated by using 50 fs laser pulses with 400 nm central wavelength and a Cold Target Recoil Ion Momentum Spectrometer (COLTRIMS), known as Reaction Microscope (ReMi). It was found that singly excited Rydberg states play a dominant role in the bound ionization process. In order to examine the importance of these Rydberg states for the dissociative ionization, the electron nuclear correlation and electron emission asymmetry was studied experimentally and theoretically. The kinetic energy distribution of the ions is simulated by numerically solving the time-dependent Schrödinger equation, whereas the electron localization asymmetry is modeled with a semiclassical theory. The presented findings indicate that dissociation via the H2+ 1sσg state is much less pronounced than commonly believed. Singly-excited Rydberg states are found to play the most important role in multiphoton bound and dissociative ionization of molecular hydrogen with 400 nm photons. The second part of the thesis reports about a pump-probe measurement using a pulse shaper setup in 4f geometry. To our knowledge this is the first report about combining a pulse shaper with a ReMi. The experimental data is compared to a former pump-probe measurement that uses a Mach-Zehnder interferometer to confirm the correct operation of the pulse shaper

Vortices in quantum droplets: Analogies between boson and fermion systems

The main theme of this review is the many-body physics of vortices in quantum droplets of bosons or fermions, in the limit of small particle numbers. Systems of interest include cold atoms in traps as well as electrons confined in quantum dots. When set to rotate, these in principle very different quantum systems show remarkable analogies. The topics reviewed include the structure of the finite rotating many-body state, universality of vortex formation and localization of vortices in both bosonic and fermionic systems, and the emergence of particle-vortex composites in the quantum Hall regime. An overview of the computational many-body techniques sets focus on the configuration interaction and density-functional methods. Studies of quantum droplets with one or several particle components, where vortices as well as coreless vortices may occur, are reviewed, and theoretical as well as experimental challenges are discussed.Comment: Review article, 53 pages, 53 figure

The quantum phases of matter

I present a selective survey of the phases of quantum matter with varieties of many-particle quantum entanglement. I classify the phases as gapped, conformal, or compressible quantum matter. Gapped quantum matter is illustrated by a simple discussion of the Z_2 spin liquid, and connections are made to topological field theories. I discuss how conformal matter is realized at quantum critical points of realistic lattice models, and make connections to a number of experimental systems. Recent progress in our understanding of compressible quantum phases which are not Fermi liquids is summarized. Finally, I discuss how the strongly-coupled phases of quantum matter may be described by gauge-gravity duality. The structure of the large N limit of SU(N) gauge theory, coupled to adjoint fermion matter at non-zero density, suggests aspects of gravitational duals of compressible quantum matter.Comment: 35 pages, 21 figures; Rapporteur presentation at the 25th Solvay Conference on Physics, "The Theory of the Quantum World", Brussels, Oct 2011; (v2+v3+v4) expanded holographic discussion and referencin

Characterization of anammox hydrazine dehydrogenase, a key N2-producing enzyme in the global nitrogen cycle

Anaerobic ammonium-oxidizing (anammox) bacteria derive their energy for growth from the oxidation of ammonium with nitrite as the electron acceptor. N2, the end product of this metabolism, is produced from the oxidation of the intermediate, hydrazine (N2H4). Previously, we identified N2-producing hydrazine dehydrogenase (KsHDH) from the anammox organism Kuenenia stuttgartiensis as the gene product of kustc0694 and determined some of its catalytic properties. In the genome of K. stuttgartiensis, kustc0694 is one out of ten paralogs related to octaheme hydroxylamine (NH2OH) oxidoreductase (HAO). Here, we characterized KsHDH as a covalently cross-linked homotrimeric octaheme protein as found for HAO and HAOrelated hydroxylamine-oxidizing enzyme kustc1061 (KsHOX) from K. stuttgartiensis. Interestingly, the HDH trimers formed octamers in solution, each octamer harbouring an amazing 192 c-type heme moieties. While HAO and KsHOX are capable of hydrazine oxidation as well, KsHDH was highly specific for this activity. To understand this specificity, we performed detailed amino acid sequence analyses and investigated the catalytic and spectroscopic (electronic absorbance, EPR) properties of KsHDH in comparison with the well-defined HAO and HOX. We conclude that HDH specificity is most likely derived from structural changes around the catalytic heme 4 (“P460”) and of the electron-wiring circuit comprising seven His/His-ligated c-type hemes in each subunit. These nuances make HDH a globally prominent N2-producing enzyme, next to nitrous oxide (N2O) reductase from denitrifying microorganisms

Bulk and Boundary Invariants for Complex Topological Insulators: From K-Theory to Physics

This monograph offers an overview on the topological invariants in fermionic topological insulators from the complex classes. Tools from K-theory and non-commutative geometry are used to define bulk and boundary invariants, to establish the bulk-boundary correspondence and to link the invariants to physical observables.Comment: Monograph in Springer Series in Mathematical Physics Studies, see ISBN below. Correction of a few remaining typos. ISBN 978-3-319-29350-9, eBook ISBN 978-3-319-29351-6, (Springer, 2016