Title Promoter Affiliations Abstract "Bose-Einstein condensation of ultracold atoms out of equilibrium." "Michiel Wouters" "Theory of quantum systems and complex systems" "Superfluids form a phase of matter, distinct from the gaseous, fluid and solid states, whose most remarkable characteristic is a vanishing viscosity. This absence of friction is a consequence of the fact that all particles move together, in analogy to the photons that come out of a laser. Lasers and superfluids share the coherence of the particles (atoms and photons respectively), but an important difference between them is that the former are driven (e.g. by an electrical current), where the latter are in thermal equilibrium. The need for the driving of the laser is a direct consequence of its usefulness as a source of coherent photons. Recently, several research activities have developed to bridge the differences between the various forms of coherent matter. From the photonic side, experiments have been performed where the photons come very close to thermal equilibrium by working with efficient thermalization mechanisms and long photon life times. From the superfluid atomic side, experiments have been performed where atom losses were induced by an electron beam, that are replenished by a nearby atomic cloud. The aim of this project is to construct theoretical descriptions of atomic superfluids that are driven away from thermal equilibrium by particle losses. Based on previous studies of photonic systems, we expect that the phase transition between the normal and coherent phases as well as their vortex properties will be modified by the atom losses." "Investigation of Compression Modes in Nuclei Far from Stability" "Riccardo Raabe" "Nuclear and Radiation Physics" "The density of matter in a nucleus is extremely high: about 10000 billions more dense than gold, which in turn is 20 times more dense than water. In nature, only collapsed stars and black holes have a higher density. Nevertheless, it is possible to further compress nuclear matter: nuclei can be squeezed and elongated like a spring, of course in three dimensions. Oscillations that are created in this way are called compression modes of the nucleus. Their characteristics are closely related to the very nature of nuclear matter (expressed by its ""equation of state"") but also to the macroscopic phenomenon of the late stages of the evolution of a star, where density may reach those extraordinary values.Information about the rate at which nuclear matter can be compressed is difficult to obtain. Experimentally, it can be determined by studying a particular class of collisions between nuclei, for which only a small momentum is transferred to a target nucleus. The response of the nucleus is then similar to that of an elastic medium, in which compression and expansion waves are established in so-called giant resonances.We intend to study such compression modes in a large range of nuclei, in order to better constrain the present known value of the compressibility. Because some of those nuclei only exist for a very short time, we will optimise a cunning detection technique, which employs a modern version of the well-known particle-tracking detectors." "Computational modeling of materials: from atomistic properties to new functionalities." "Francois Peeters" "Katholieke Universiteit Leuven, Pennsylvania State University, Izmir Institute of Technology, Federal University Ceara, Shahid Rajaee University, IMEC, Catholic University of Louvain, Université d'Orléans, Ghent University, University of Liège, University of Camerino, Condensed Matter Theory" "The WOG ""Computational modeling of materials"" aims to: - Promote interdisciplinary computational material research, bringing together groups from physics, chemistry and materials science, and providing them with a platform on which to share their expertise in order to arrive at an integrated and pragmatic approach in order to develop opto-electronic, thermodynamic and structural properties of materials to study. - Develop new techniques and implement them in computer software that can be subsequently used in either academic or industrial contexts" "Atomic thin membranes for water and ion transport." "Erik Neyts" "Plasma Lab for Applications in Sustainability and Medicine - Antwerp (PLASMANT)" "Membranes are used for different separation processes with applications in areas as diverse as water desalination, gas separation, energy technologies, microfluidics and medicine. Due to its atomic thickness and its exceptional mechanical properties, graphene and related materials have opened up new possibilities in membrane technologies. Such membranes will be investigated for water and hydrogen transport, ion sieving and hydrogen isotope separation. Fundamental insights into mass transport at the nanoscale will be obtained through theoretical and computational modelling with intensive collaboration with experimentalists for validation." "Computational modeling of materials: from atomistic properties to new functionalities." "Katholieke Universiteit Leuven, Pennsylvania State University, Izmir Institute of Technology, Federal University Ceara, Shahid Rajaee University, IMEC, Catholic University of Louvain, Université d'Orléans, Ghent University, University of Liège, University of Camerino, Electron microscopy for materials research (EMAT)" "Computational modeling is an essential factor in the study of the properties of materials. Nowadays, computational modeling is extensively used to predict and develop new materials. This requires a thorough knowledge of the local atomic (structural and electronic) structure and its influence on the macroscopic properties. Although, in principle, all materials can be described with the laws of quantum mechanics, it is impossible in practice to derive all material properties from these. Even with today's most powerful supercomputers, quantum mechanical electronic structure calculations are limited to a thousand atoms and to a maximum of 1 ns. To study length and time scales that go beyond these atomic scales, (semi-) empirical techniques are used and further developed through multiscale modeling. Transitions between models describing at different time and length scales are achieved by studying the relevant scale with the appropriate computational techniques. In order to have a thorough understanding of materials properties it is therefore important for collaborations between computational groups with expertise on different methods to flourish." "Large deviations in non-equilibrium processes" "Bart CLEUREN, Christian VAN DEN BROECK" "Theory lab" "The theory of equilibrium statistical mechanics is one of the most powerful theories in physics. Its biggest asset is perhaps its simplicity, as one can describe the full thermodynamic picture of a system with only a few thermodynamic potentials, such as energy. The weakness of this theory is that it only works for systems that are always in equilibrium, or driven infinitely slowly. An assumption which is never strictly valid in reality. A full thermodynamic picture can therefore only be given if one also includes non-equilibrium effects. This raises the question wether one can formulate a general theory comparable with equilibrium statistical physics for non-equilibrium systems. Over the last two decades, much progress has been made in this direction, and it is becoming clear that such a general theory should be rooted in the mathematical framework of large deviation theory. The goal of this project would be to tackle several problems in non-equilibrium statistical mechanics from a large-deviation point of view, in this way advancing the construction of a general theory for the thermodynamics of non-equilibrium systems." "Tunable in-plane and out-of-plane anisotropy in two dimensional materials." "Condensed Matter Theory" "Two-dimensional (2D) single-layer materials are currently a very important topic in materials science because of their unique properties. A particular class of such materials are one those with low symmetry and with anisotropy which are important candidates for various applications in nanotechnology ranging from optoelectronic to spin-based devices and even to field effect transistors (FET) and nano optical waveguide polarizers. The prediction of novel stable anisotropic single-layer crystals and a deeper understanding of their physical properties is very important. The understanding of their Raman spectrum is essential in distinguishing between the different structural phases and in determining the crystal orientation of the material. The present project puts forward a method to determine the crystal orientation of anisotropic materials through resonant Raman measurements from both first- and second-order Raman spectra. I will contribute to the study of first- and second-order resonant Raman scattering in anisotropic materials, from which information on the electron-phonon and exciton-phonon interactions can be obtained. These are very important for the understanding of light-matter interactions. Moreover, 2D materials are often subject to external forces such as strain and charge transfer to or from the substrate. Therefore, these effects on the physical properties of anisotropic materials will be thoroughly investigated." "Atomic collapse in Dirac-like materials." "Condensed Matter Theory" "Soon after the formulation of the Dirac equation (1928), which describes relativistic particles, it was predicted that for a high charge Z of the nucleus the atom becomes unstable, leading to the phenomenon of atomic collapse. Because of the large required Z>170 value scientists were never able to verify it experimentally. However, the discovery of graphene and the fact that its charge carriers mimic relativistic (quasi-)particles opened up a new window on atomic collapse, which was recently observed experimentally in graphene. Using this recent observation as motivation, we will theoretically investigate the atomic collapse phenomenon in graphene and other Dirac-like materials having very different energy dispersions. We will study how the various differences between these materials influence the atomic collapse phenomenon and study how this phenomenon can be tuned by external electric and magnetic fields. The purpose of this proposal is two fold: 1) to study atomic collapse in different Dirac-like materials, which will give us fundamental information and understanding about atomic collapse at the relativistic level, and 2) to investigate the influence of atomic collapse on the transport of charge carriers in Dirac-like materials, providing us with very important information needed for the development of future applications ." "Many-polaron effects in a Bose-Einstein condensate." "Jacques Tempere" "Theory of quantum systems and complex systems" "A Bose-Einstein condensate (BEC) can be thought of as a gas of atoms which undergoes a transition into a specific phase at very low temperatures. In this new phase the atomic gas exhibits various peculiar properties such as superfluidity, quantized vortices and many other phenomena not expected in normal gases. One such interesting problem is that of an impurity (usually an atom of a different species) moving through a BEC. This impurity will disturb the gas around it and create a dip of lower density which it will have to drag along. This will modify the properties of the impurity and for example change the effective mass, analogous to a person having more trouble walking on a trampoline and dragging along the deformation in the fabric. Such an impurity together with the dip in density as a whole is called a Bose-polaron. In 2016 two experiments first realized condensates that contained many Bose-polarons and gave rise to an active discussion in the theoretical community. It has been shown that for an accurate theoretical description of the polaron additional correction terms had to be taken into account which were not present in previous discussions. This has been recently done for a description of single Bose-polarons. In this research these correction terms will be included to describe a system of many polarons which in combination has not been done before. The results found here will also be extended to other atomic gases called ultracold fermionic gases." "Three-dimensional characterization of the growth of anisotropic Au nanoparticles." Bals "Electron microscopy for materials research (EMAT)" "The design and synthesis of metal nanoparticles (NPs) with predefined size and shape remains a major challenge in materials science. Although the growth of Au NPs is mature, synthetic procedures have evolved largely empirically so far. Obtaining full control over the synthesis of Au NPs is of key importance toward their efficient applicability in e.g. photothermal therapy and plasmonic sensing. However, in order to optimize the synthesis protocols and obtain NPs with specific properties, a detailed quantitative structural characterization of the products during the different growth stages by advanced transmission electron microscopy (TEM) is needed. The aim of this project is to optimize TEM techniques and to develop novel three-dimensional (3D) characterization tools, adequate to elucidate different aspects in the growth of Au NPs that still remain unclear. These novel methodologies will allow me to characterize Au NPs at different growth stages, which will yield the necessary insights to gain control over both the growth of Au seeds as well as the Au NPs. A challenging and ambitious goal in this project will be to realize high throughput 3D studies to perform a statistically relevant analysis concerning the size and shape of NPs. This project will have a major impact on the synthesis of metal NPs. The outcome of our experiments will enable one to optimize the synthesis towards highly monodisperse NPs, which will lead to a more effective use in biomedical applications."