Atoms in optical lattices are promising candidates to implement quantum information processing. Their behaviour is well understood on a microscopic level, they exhibit excellent coherence properties, and they can be easily manipulated using external fields. In very deep optical lattices, each atom is restricted to a single lattice site and can be used as a qubit. If the lattice is shallow enough such that the atoms can move, their properties can be used to simulate certain condensed matter phenomena such as superconductivity. In this thesis, we show how technical problems of optical lattices such as restricted decoherence times, or fundamental shortcomings such as the lack of phonons or strong spin interactions, can be overcome by using current or near-future experimental techniques. We introduce a scheme that makes it possible to simulate model Hamiltonians known from high-temperature superconductivity. For this purpose, previous simulation schemes to realise the spin interaction terms are extended. We especially overcome the condition of a filling factor of exactly one, which otherwise would restrict the phase of the simulated system to a Mott-insulator. This scheme makes a large range of parameters accessible, which is difficult to cover with a condensed matter setup. We also investigate the properties of optical lattices submerged into a Bose-Einstein condensate (BEC). A weak-coupling expansion in the BEC-impurity interaction strength is used to derive a model that describes the lattice atoms in terms of polarons, i.e.~atoms dressed by Bogoliubov phonons. This is analogous to the description of electrons in solids, and we observe similar effects such as a crossover from coherent to incoherent transport for increasing temperatures. Moreover, the condensate mediates an attractive off-site interaction, which leads to macroscopic clusters at experimentally realistic parameters. Since the atoms in the lattice can also be used as a quantum register with the BEC mediating a two-qubit gate, we derive a quantum master equation to examine the coherence properties of the atomic qubits. We show that the system exhibits sub- and superdecoherence and that a fast implementation of the two-qubit gate competes with dephasing. Finally, we show how to realise the encoding of qubits in a decoherence-free subspace (DFS) using optical lattices. We develop methods for implementing robust gate operations on qubits encoded in a DFS exploiting collisional interactions between the atoms. We also give a detailed analysis of the performance and stability of the gate operations and show that a robust implementation of quantum repeaters can be achieved using our setup. We compare the robust repeater scheme to one that makes use of conventional qubits only, and show the conditions under which one outperforms the other.

O estudo de sistemas híbridos compostos por interfaces orgânico/inorgânico, ou sólido/líquido, tem apresentado crescente interesse nas áreas de eletroquímica e nanotecnologia. Além de objetos de pesquisas básicas, estes sistemas apresentam um potencial para inúmeras aplicações, dentre elas: línguas eletrônicas, \\emph{self-assembled monolayers} (SAMs), dispositivos fotovoltáicos, baterias alternativas, carreadores de drogas, entre outras. Em especial, o uso de superfícies de ouro em pesquisas ocorre principalmente por causa da natureza inerte deste material, permitindo explorar uma ampla quantidade de potenciais eletrostáticos que induzem a eletrólise ou reações eletroquímicas em outras superfícies. O estudo de voltametria cíclica em SAMs formadas por cadeias polipeptídicas funcionalizadas com ferroceno vem sendo realizado durante as duas últimas décadas. Recentemente, iniciou-se uma controvertida discussão a respeito do mecanismo de transporte eletrônico entre o centro oxidativo e o eletrodo destes sistemas. Alguns grupos argumentam a favor de tunelamento eletrônico do centro oxidativo, enquanto outros grupos têm proposto uma interação de pares \\emph{elétron-buraco} dos grupos amida dos peptídeos. Além disto, interfaces com sistemas primitivos, como por exemplo a água, ainda são temas de pesquisa correntes de diversos grupos de pesquisa, devido à complexidade dos resultados experimentais reportados. De forma a contribuir com estas discussões correntes na literatura, selecionamos dois problemas distintos utilizando a superfície Au(111) como base comum: i) estudo do mecanismo de transferência de carga de um peptídeo funcionalizado com ferroceno; ii) estudo das propriedades eletrônicas e estruturais da água interagindo com NaCl. Para realizarmos a investigação das propriedades eletrônicas, empregamos a Teoria do Funcional da Densidade no esquema de Kohn-Sham (KS). Para analisar as propriedades dinâmicas e estruturais, foi utilizada também a técnica de dinâmica molecular clássica (MD). A partir de diversos modelos da interação do peptídeo sobre Au(111), investigamos as densidades de estados, cargas de Löwdin e funções de onda de KS. Notamos a presença de estados eletrônicos localizados tanto sobre o ferroceno quanto sobre o ouro, ambos sempre próximos da região da energia de Fermi, em todos os casos propostos. Estes resultados sugerem um tunelamento eletrônico entre sítio do ferroceno e a superfície Au(111) como o mecanismo de transferência eletrônica. Para o caso do sal dissociado em água, investigamos e discutimos a estrutura eletrônica em diversas situações e configurações. Além disto, realizamos um estudo MD, onde observamos que o ordenamento das moléculas de água é bastante sensível à presença da superfície Au(111). Os resultados obtidos apresentam uma visão ampla dos comportamentos eletrônicos e dinâmicos de sistemas envolvendo a superficie Au(111) que discutem questões correntes na literatura. / The study of hybrid interfaces, e.g. organic/inorganic or solid/liquid, have been showing an increasing interest in electrochemistry and nanotechnology. Within this subject, there are basic and applied studies, such as electronic tongues, self-assembled monolayers (SAMs), photovoltaic devices, alternative batteries, drug carriers and others. In special, the preference for gold surface occurs due to its inert nature, allowing the exploration of a wide range of electrostatic potentials which induces electrolysis and chemical reactions in other surfaces. The Cyclic Voltammetry study in Peptide-SAMs modified by ferrocene has been investigated in the literature. In recent years, a controversy on the charge transfer mechanism in biological materials started: at one hand, there are arguments in favor of an electronic tunneling process from the oxidative center to the eletrode; on the other hand, some authors suggest electronic hopping from the amide groups of the peptides, generating an electron-hole pair that ``walks\'\' from the ferrocene to the eletrode. Furthermore, systems with primitive interfaces, such as water, are also subject of current research due to the complexity of the experimental results reported in the literature. Within this scenario, we selected two distinct problems using the surface Au(111): i) the study of charge transfer mechanism using a peptide modified by ferrocene; ii) the study of electronic and structural properties of water interacting with NaCl. In order to obtain the electronic properties, we employed the Density Functional Theory in the Kohn-Sham (KS) scheme. For the structural and dynamics properties, we also used classical molecular dynamics (MD). Based on different models for the ferrocene-peptide/Au(111) interface, we investigate the density of states, Löwdin charges and KS wavefunctions. We notice the presence of localized electronic states on the ferrocene and gold which are close to the Fermi energy in all studied cases. These results suggest an electronic tunneling from the ferrocene site to the surface Au(111) as the mechanism for the charge transfer. In the case of salt dissociated in water, we investigated the electronic properties in several different configurations. Furthermore, in a MD perspective, the orientation of the water molecules presented a high sensitivity for the Au(111) interface. These results represent a wide view of the electronic and dynamic behavior of systems using the surface Au(111) as a common subject.

O estudo de sistemas híbridos compostos por interfaces orgânico/inorgânico, ou sólido/líquido, tem apresentado crescente interesse nas áreas de eletroquímica e nanotecnologia. Além de objetos de pesquisas básicas, estes sistemas apresentam um potencial para inúmeras aplicações, dentre elas: línguas eletrônicas, \\emph{self-assembled monolayers} (SAMs), dispositivos fotovoltáicos, baterias alternativas, carreadores de drogas, entre outras. Em especial, o uso de superfícies de ouro em pesquisas ocorre principalmente por causa da natureza inerte deste material, permitindo explorar uma ampla quantidade de potenciais eletrostáticos que induzem a eletrólise ou reações eletroquímicas em outras superfícies. O estudo de voltametria cíclica em SAMs formadas por cadeias polipeptídicas funcionalizadas com ferroceno vem sendo realizado durante as duas últimas décadas. Recentemente, iniciou-se uma controvertida discussão a respeito do mecanismo de transporte eletrônico entre o centro oxidativo e o eletrodo destes sistemas. Alguns grupos argumentam a favor de tunelamento eletrônico do centro oxidativo, enquanto outros grupos têm proposto uma interação de pares \\emph{elétron-buraco} dos grupos amida dos peptídeos. Além disto, interfaces com sistemas primitivos, como por exemplo a água, ainda são temas de pesquisa correntes de diversos grupos de pesquisa, devido à complexidade dos resultados experimentais reportados. De forma a contribuir com estas discussões correntes na literatura, selecionamos dois problemas distintos utilizando a superfície Au(111) como base comum: i) estudo do mecanismo de transferência de carga de um peptídeo funcionalizado com ferroceno; ii) estudo das propriedades eletrônicas e estruturais da água interagindo com NaCl. Para realizarmos a investigação das propriedades eletrônicas, empregamos a Teoria do Funcional da Densidade no esquema de Kohn-Sham (KS). Para analisar as propriedades dinâmicas e estruturais, foi utilizada também a técnica de dinâmica molecular clássica (MD). A partir de diversos modelos da interação do peptídeo sobre Au(111), investigamos as densidades de estados, cargas de Löwdin e funções de onda de KS. Notamos a presença de estados eletrônicos localizados tanto sobre o ferroceno quanto sobre o ouro, ambos sempre próximos da região da energia de Fermi, em todos os casos propostos. Estes resultados sugerem um tunelamento eletrônico entre sítio do ferroceno e a superfície Au(111) como o mecanismo de transferência eletrônica. Para o caso do sal dissociado em água, investigamos e discutimos a estrutura eletrônica em diversas situações e configurações. Além disto, realizamos um estudo MD, onde observamos que o ordenamento das moléculas de água é bastante sensível à presença da superfície Au(111). Os resultados obtidos apresentam uma visão ampla dos comportamentos eletrônicos e dinâmicos de sistemas envolvendo a superficie Au(111) que discutem questões correntes na literatura. / The study of hybrid interfaces, e.g. organic/inorganic or solid/liquid, have been showing an increasing interest in electrochemistry and nanotechnology. Within this subject, there are basic and applied studies, such as electronic tongues, self-assembled monolayers (SAMs), photovoltaic devices, alternative batteries, drug carriers and others. In special, the preference for gold surface occurs due to its inert nature, allowing the exploration of a wide range of electrostatic potentials which induces electrolysis and chemical reactions in other surfaces. The Cyclic Voltammetry study in Peptide-SAMs modified by ferrocene has been investigated in the literature. In recent years, a controversy on the charge transfer mechanism in biological materials started: at one hand, there are arguments in favor of an electronic tunneling process from the oxidative center to the eletrode; on the other hand, some authors suggest electronic hopping from the amide groups of the peptides, generating an electron-hole pair that ``walks\'\' from the ferrocene to the eletrode. Furthermore, systems with primitive interfaces, such as water, are also subject of current research due to the complexity of the experimental results reported in the literature. Within this scenario, we selected two distinct problems using the surface Au(111): i) the study of charge transfer mechanism using a peptide modified by ferrocene; ii) the study of electronic and structural properties of water interacting with NaCl. In order to obtain the electronic properties, we employed the Density Functional Theory in the Kohn-Sham (KS) scheme. For the structural and dynamics properties, we also used classical molecular dynamics (MD). Based on different models for the ferrocene-peptide/Au(111) interface, we investigate the density of states, Löwdin charges and KS wavefunctions. We notice the presence of localized electronic states on the ferrocene and gold which are close to the Fermi energy in all studied cases. These results suggest an electronic tunneling from the ferrocene site to the surface Au(111) as the mechanism for the charge transfer. In the case of salt dissociated in water, we investigated the electronic properties in several different configurations. Furthermore, in a MD perspective, the orientation of the water molecules presented a high sensitivity for the Au(111) interface. These results represent a wide view of the electronic and dynamic behavior of systems using the surface Au(111) as a common subject.

In this thesis we investigate strongly-correlated states of ultracold bosonic atoms in rotating ring lattices and arrays of double-well potentials. In the first part of the thesis, we study the tunneling dynamics of ultracold bosons in double-well potentials. In the non-interacting limit single-particle transitions dominate, while in the interaction-dominated regime correlated tunneling of all particles prevails. At intermediate times of the many-particle flopping process correlated states occur, but the timescales of these processes increase dramatically with the number of particles. Using an array of double-well potentials, a large number of such few-particle superposition states can be produced in parallel. In the second part of the thesis, we study the effects of rotation on ultracold bosons confined to one-dimensional ring lattices. We find that at commensurate filling there exists a critical rotation frequency, at which the ground state of the weakly-interacting gas is fragmented into a macroscopic superposition of different quasi-momentum states. We demonstrate that the generation of such superposition states using slightly non-uniform ring lattices has several practical advantages. Moreover, we show that different quasi-momentum states can be distinguished in time-of-flight absorption imaging and propose to probe correlations via the many-body oscillations induced by a sudden change in the rotation frequency. Finally, we compare these macroscopic superposition states to those occurring in superconducting quantum interference devices. In the third part of the thesis, we demonstrate the creation of entangled states with ultracold bosonic atoms by dynamical manipulation of the shape of the lattice potential. To this end, we consider an optical superlattice that allows both the splitting of each site into a double-well potential and the variation of the height of the potential barrier between the sites. We show how to use this array of double-well potentials to perform entangling operations between neighboring qubits encoded on the Zeeman levels of the atoms. As one possible application, we present a method of realizing a resource state for measurement-based quantum computation via Bell-pair measurements. In the final part of the thesis, we study ultracold bosons on a two-dimensional square lattice in the presence of an effective magnetic field and point out a couple of features this system has in common with ultracold bosons in one-dimensional rotating ring lattices.

Molecular dynamics (MD) simulations are used to compute the equilibrium dynamics of a single component fluid with Yukawa interaction potential v(r) = (Ze)^2 exp(−r/λs )/4π eps_0 r. This system, which is known as the Yukawa one-component plasma (YOCP), represents a simplified description of a non-ideal plasma consisting of ions, charge Ze, and electrons. For finite screening lengths λs, the MD results are used to investigate the domain of validity of the hydrodynamic description, i.e., the description given by the Navier-Stokes equations. The way in which this domain depends on the thermodynamic conditions of the YOCP, as well as the strength and range of the interactions, is determined. Remarkably, it is found that the domain of validity is completely determined by the range of the interactions (i.e., λs); this alone determines the maximum wave number k_max at which the hydrodynamic description is applicable. The dynamics of the YOCP at wavevectors beyond k_max are then investigated; these are shown to be in striking agreement with a simple and well known generalisation of the Navier-Stokes equations. In the extreme case of the Coulomb interaction potential (λs = ∞), the very existence of a hydrodynamic description is a known but unsolved problem [Baus & Hansen, 1980]. For this important special case, known as the one-component plasma (OCP), it is shown that the ordinary hydrodynamic description is never valid. Since the OCP is the prototypical system representing a non-ideal plasma, a number of different approaches for modelling its dynamics have been formulated previously. By computing the relevant quantities with MD, the applicability of a number of models proposed in the literature is examined for the first time.

A measurement-independent formulation of quantum mechanics called ‘regular histories’ (RH) is presented, able to reproduce the predictions of the standard formalism without the need to for a quantum-classical divide or the presence of an observer. It applies to closed systems and features no wave-function collapse. Weights are assigned only to histories satisfying a criterion called ‘regularity’. As the set of regular histories is not closed under the Boolean operations this requires a new con- cept of weight, called ‘likelihood’. Remarkably, this single change is enough to overcome many of the well-known obstacles to a sensible interpretation of quantum mechanics. For example, Bell’s theorem, which makes essential use of probabilities, places no constraints on the locality properties of a theory based on likelihoods. Indeed, RH is both counter- factually definite and free from action-at-a-distance. Moreover, in RH the meaningful histories are exactly those that can be witnessed at least in principle. Since it is especially difficult to make sense of the concept of probability for histories whose occurrence is intrinsically indeterminable, this makes likelihoods easier to justify than probabilities. Interaction with the environment causes the kinds of histories relevant at the macroscopic scale of human experience to be witnessable and indeed to generate Boolean algebras of witnessable histories, on which likelihoods reduce to ordinary probabilities. Further- more, a formal notion of inference defined on regular histories satisfies, when restricted to such Boolean algebras, the classical axioms of implication, explaining our perception of a largely classical world. Even in the context of general quantum histories the rules of reasoning in RH are remark- ably intuitive. Classical logic must only be amended to reflect the fundamental premise that one cannot meaningfully talk about the occurrence of unwitnessable histories. Crucially, different histories with the same ‘physical content’ can be interpreted in the same way and independently of the family in which they are expressed. RH thereby rectifies a critical flaw of its inspiration, the consistent histories (CH) approach, which requires either an as yet unknown set selection rule or a paradigm shift towards an un- conventional picture of reality whose elements are histories-with-respect-to-a-framework. It can be argued that RH compares favourably with other proposed interpretations of quantum mechanics in that it resolves the measurement problem while retaining an essentially classical worldview without parallel universes, a framework-dependent reality or action-at-a-distance.

The lack of direct evidence for physics beyond the SM at the LHC has led some to reevaluate the need for such physics to solve the hierarchy problem. Instead, the notion that the SM, or something like it, is valid up to the Planck scale and that technical naturalness is sufficient for solving the hierarchy problem has been suggested. This thesis examines minimal extensions of the SM that address its phenomenological and theoretical shortcomings while avoiding new physics between the electroweak and Planck scales that introduces a hierarchy problem. This thesis first studies two issues with the vMSM - an extension of the SM by three right-handed neutrinos - and their possible solutions. The first issue is the tension between dark matter production in the nuMSM and constraints from the Lyman-alpha forest data. To avoid this tension, the vMSM is extended by a Higgs singlet Φ and neutrino dark matter is produced through the decays of Φ rather than through left-right neutrino mixing. It is shown that the hierarchical parameters of this model can arise from symmetries broken at or near the Planck scale for two specific examples: one in which Φ stabilizes the electroweak vacuum and one in which Φ is a light inflaton. The second issue pertains to Higgs ξ-inflation. In the vMSM, a large non-minimal coupling ξ of the Higgs to gravity gives inflation but leads to a possible violation of perturbative unitarity below the inflationary scale. A study of Higgs ξ-inflation with M_h ≃ 125-126 GeV, for which the Higgs self-coupling λ runs to small values near the Planck scale, is carried out. It is shown that small λ can significantly reduce ξ required for inflation, but ξ cannot be small enough to address the possible unitarity issue. For small λ, a new region of Higgs ξ-inflation with a large tensor-to-scalar ratio r that is consistent with BICEP2 is discovered. This thesis then studies the technical naturalness and cosmology of a model that addresses the strong CP problem. It is shown that a classically scale invariant DFSZ invisible aξon model with a Peccei-Quinn scalar S, whose couplings to the SM are ultra-weak, can solve the strong CP problem and generate electroweak symmetry breaking via the Coleman-Weinberg mechanism. The ultra-weak couplings of S are natural due to an underlying approξmate shift symmetry. The model contains a light pseudo-Goldstone dilaton that can be consistent with cosmological bounds while the aξon can be the dark matter of the universe. Finally, a summary of the thesis is presented and future research topics are suggested.

Sólitons são soluções clássicas de equações de campos não lineares, que possuem energia finita e densidade de energia localizada. Eles constituem pacotes de energia que se movem de maneira uniforme e não dispersiva, assemelhando-se a partículas estendidas. Quando se estuda um sistema à temperatura finita é possível tecer um paralelo entre a teoria quântica de campos e a mecânica estatística. Neste trabalho calculamos, na aproximação de um laço, a correção quântica à massa do kink do modelo 4 acoplado a um campo fermiônico. As contribuições bosônica e fermiônica são calculadas à temperatura zero e o comportamento das flutuações a temperatura finita também é analisado. / Solitons are classical solutions of non-linear field equations, that have finite energy and localised energy density. They constitute non-dispersive localised packages of energy moving uniformly, resembling extended particles. When studying a system at finite temperature one can make an analogy between quantum field theory and statistical mechanics. In this work we calculate, in one loop approximation, the quantum correction to the mass of the kink of the model 4 coupled to a fermionic field. The bosonic and fermionic contributions are calculated at zero temperature and the behavior of the finite temperature fluctuations are also analysed.

Sólitons são soluções clássicas de equações de campos não lineares, que possuem energia finita e densidade de energia localizada. Eles constituem pacotes de energia que se movem de maneira uniforme e não dispersiva, assemelhando-se a partículas estendidas. Quando se estuda um sistema à temperatura finita é possível tecer um paralelo entre a teoria quântica de campos e a mecânica estatística. Neste trabalho calculamos, na aproximação de um laço, a correção quântica à massa do kink do modelo 4 acoplado a um campo fermiônico. As contribuições bosônica e fermiônica são calculadas à temperatura zero e o comportamento das flutuações a temperatura finita também é analisado. / Solitons are classical solutions of non-linear field equations, that have finite energy and localised energy density. They constitute non-dispersive localised packages of energy moving uniformly, resembling extended particles. When studying a system at finite temperature one can make an analogy between quantum field theory and statistical mechanics. In this work we calculate, in one loop approximation, the quantum correction to the mass of the kink of the model 4 coupled to a fermionic field. The bosonic and fermionic contributions are calculated at zero temperature and the behavior of the finite temperature fluctuations are also analysed.

In relativistischen Schwerionenkollisionen spielen seltsame Teilchen bei der Untersuchung heißer und dichter Materie eine wichtige Rolle. Dazu wird die Produktion von Hadronen mit Strangeness-Inhalt mit Hilfe eines Transportmodells vom Boltzmann-Ühling-Uhlenbeck (BUU)-Typ numerisch behandelt. Aktuelle Messungen der HADES-Kollaboration bezüglich K+- - und phi-Spektren bilden dabei den entsprechenden experimentellen Rahmen. Darüber hinaus wird das doppelt-seltsame Hyperon Xi- unterhalb der freien NN-Produktionsschwelle analysiert. Hadronische Multiplizitäten, Transversalimpuls- und Rapiditätsspektren werden mit neuen experimentellen Ergebnissen verglichen. Weiterhin werden Massenverschiebungen im Medium, die nukleare Zustandsgleichung sowie das mittlere Feld der Nukleonen berücksichtigt. Neben der Untersuchung von Kern-Kern-Stößen bietet sich in Proton-Kern-Kollisionen ein Vergleich mit jüngsten ANKE-Daten im Hinblick auf die phi-Ausbeute an. Mit Hilfe des BUU-Transportcodes wurden Tranzparenzverhältnisse ermittelt und die Absorption von phi-Mesonen untersucht. Dabei sind sekundäre phi-Produktionskanäle, Isospin-Asymmetrie und Detektorakzeptanzen von Bedeutung und werden systematisch für verschiedene Systemgrößen analysiert. Die impulsintegrierten Boltzmann-Gleichungen dienen im Rahmen einer kinetischen Nichtgleichgewichtsdynamik der Beschreibung hochkomprimierter nuklearer Materie auf hadronischem Niveau, wie sie sowohl beim Urknall als auch bei ultra-relativistischen Schwerionenkollisionen auftritt. Diese Theorie wird am Beispiel von Antiprotonen untersucht und unter Berücksichtigung verschiedener Expansionsmodelle numerisch ausgewertet. Dabei wird die Evolution der Proton- und Antiprotondichten bis zum Ausfrieren für SPS- und RHIC-Energien mittels eines hadro-chemischen Resonanzgasmodells als möglicher Lösungsansatz des "Antiproton-Puzzles" analysiert. Diskutiert wird darüber hinaus das Verhalten baryonischer Materie und Antimaterie im frühen Universum und der adiabatische Pfad kosmischer Materie im QCD-Phasendiagramm. / Strange particles play an important role as probes of relativistic heavy-ion collisions where hot and dense matter is studied. The focus of this thesis is on the production of strange particles within a transport model of Boltzmann-Ühling-Uhlenbeck (BUU) type. Current data of the HADES Collaboration concerning K+- and phi spectra provide the appropriate experimental framework. Moreover, the double-strange hyperon Xi- is analyzed below the free NN production threshold. Hadron multiplicities, transverse-momentum and rapidity spectra are compared with recent experimental data. Further important issues are in-medium mass shifts, the nuclear equation of state as well as the mean field of nucleons. Besides the study of AA collisions a comparison with recent ANKE data regarding the phi yield in pA collisions is done. Transparency ratios are determined and primarily investigated for absorption of phi mesons by means of the BUU transport code. Thereby, secondary phi production channels, isospin asymmetry and detector acceptance are important issues. A systematic analysis is presented for different system sizes. The momentum integrated Boltzmann equations describe dense nuclear matter on a hadronic level appearing in the Big Bang as well as in little bangs, in the context of kinetic off-equilibrium dynamics. This theory is applied to antiprotons and numerically calculated under consideration of various expansion models. Here, the evolution of proton- and antiproton densities till freeze-out is analyzed for ultra-relativistic heavy-ion collisions within a hadrochemic resonance gas model acting as a possible ansatz for solving the "antiproton puzzle". Furthermore, baryonic matter and antimatter is investigated in the early universe and the adiabatic path of cosmic matter is sketched in the QCD phase diagram.