ERC FUNDED PROJECTS

Fault-tolerant topological quantum computation has become one of the most exciting research directions in modern condensed matter physics. As a key operation the braiding of non-Abelian anyons has been proposed theoretically. Such exotic quasiparticles can be realized as zero-energy Majorana bound states at the ends of one-dimensional magnetic nanowires in proximity to s-wave superconductors in the presence of high spin-orbit coupling. In contrast to previous attempts to realize such systems experimentally, based on the growth of semiconducting nanowires or the self-assembly of ferromagnetic nanowires on s-wave superconductors, we propose to design Majorana bound states in artificially constructed single-atom chains with non-collinear spin-textures on elemental superconducting substrates using scanning tunnelling microscope (STM)-based atom manipulation techniques. We would like to study at the atomic level the formation of Shiba bands as a result of hybridization of individual Shiba impurity states as well as the emergence of zero-energy Majorana bound states as a function of chain structure, length, and composition. Moreover, we will construct model-type platforms, such as T-junctions, rings, and more complex network structures with atomic-scale precision as a basis for demonstrating the manipulation and braiding of Majorana bound states. We will make use of sophisticated experimental techniques, such as spin-resolved scanning tunnelling spectroscopy (STS) at micro-eV energy resolution, scanning Josephson tunnelling spectroscopy, and multi-probe STS under well-defined ultra-high vacuum conditions, in order to directly probe the nature of the magnetic state of the atomic wires, the spin-polarization of the emergent Majorana states, as well as the spatial nature of the superconducting order parameter in real space. Finally, we will try to directly probe the quantum exchange statistics of non-Abelian anyons in these atomically precise fabricated model-type systems.

2 499 750 €

Start date: 2019-01-01, End date: 2023-12-31

What makes for a valuable and good life is a question that many people in the contemporary world ask themselves, yet it is one that social science research has seldom addressed. Only recently have scholars started undertaking inductive comparative research on different notions of the ‘good life’, highlighting socio-cultural variations and calling for a better understanding of the different imaginaries, aspirations and values that guide people in their quest for better living conditions. Research is still lacking, however, on how people themselves evaluate, compare, and put into perspective different visions of good living and their socio-cultural anchorage. This project addresses such questions from an anthropological perspective, proposing an innovative study of how ideals of the good life are articulated, (re)assessed, and related to specific places and contexts as a result of the experience of crisis and migration. The case studies chosen to operationalize these lines of enquiry focus on the phenomenon of return migration, and consist in an analysis of the imaginaries and experience of return by Ecuadorian and Cuban men and women who migrated to Spain, are dissatisfied with their life there, and envisage/carry out the project of going back to their countries of origin (Ecuador and Cuba respectively). The project’s ambition is to bring together and contribute to three main scholarly areas of enquiry: 1) the study of morality, ethics and what counts as ‘good life’, 2) the study of the field of economic practice, its definition, value regimes, and ‘crises’, and 3) the study of migratory aspirations, projects, and trajectories. A multi-sited endeavour, the research is designed in three subprojects carried out in Spain (PhD student), Ecuador (Post-Doc), and Cuba (PI), in which ethnographic methods will be used to provide the first empirically grounded study of the links between notions and experiences of crisis, return migration, and the (re)assessment of good living.

1 500 000 €

Start date: 2018-02-01, End date: 2023-01-31

Topology provides mathematical tools to sort objects according to global properties regardless of local details, and manifests itself in various fields of physics. In solid-state physics, specific topological properties of the band structure, such as a band inversion, can for example robustly enforce the appearance of spin-polarized conducting states at the boundaries of the material, while its bulk remains insulating. The boundary states of these ‘topological insulators’ in fact provide a support system to encode information non-locally in ‘topological quantum bits’ robust to local perturbations. The emerging ‘topological quantum computation’ is as such an envisioned solution to decoherence problems in the realization of quantum computers. Despite immense theoretical and experimental efforts, the rise of these new materials has however been hampered by strong difficulties to observe robust and clear signatures of their predicted properties such as spin-polarization or perfect conductance. These challenges strongly motivate my proposal to study two-dimensional topological insulators, and in particular explore the unknown dynamics of their topological edge states in normal and superconducting regimes. First it is possible to capture information both on charge and spin dynamics, and more clearly highlight the basic properties of topological edge states. Second, the dynamics reveals the effects of Coulomb interactions, an unexplored aspect that may explain the fragility of topological edge states. Finally, it enables the manipulation and characterization of quantum states on short time scales, relevant to quantum information processing. This project relies on the powerful toolbox offered by radiofrequency and current-correlations techniques and promises to open a new field of dynamical explorations of topological materials.

1 499 940 €

Start date: 2018-02-01, End date: 2023-01-31

The three-dimensional organization of the genome, which strikingly correlates with gene activity, is critical for many cellular processes. The evolution of molecular techniques has allowed us to unveil chromatin structure at an unprecedented resolution. The most intriguing chromatin structures observed in animals are TADs (Topologically Associating Domains), which represent the functional and structural chromatin domains demarcating the genome. Structural proteins such as insulators proteins, on the other hand, have been shown to play crucial roles in mediating the formation of TADs. However, major structural factors relevant to chromatin structure are still waiting to be discovered in land plants. My preliminary work shows that TADs are widely distributed across the rice genome, and motif sequence analysis suggests the enrichment of plant-specific transcription factors at TAD boundaries, which jointly give rise to an exciting hypothesis that these proteins might be the long-sought-after insulators in land plants. By using various state-of-the-art molecular and computational tools, this timely project aims to fill a huge gap in plant functional genomics and substantially advance our understanding of three-dimensional chromatin structure. This project consists four major aims, which collectively will uncover the identities of plant insulator proteins and generate insights into the dynamics of structural chromatin domains during stress adaptation. Aim 1 will identify and characterize the stability and plasticity of functional chromatin domains in the rice genome during temperature stress adaptation. Aim 2 will identify insulator elements and other structural features of chromatin packing in the Marchantia polymorpha genome from a structural genomics approach. Aim 3 will establish the role of candidate proteins as plant insulators. Lastly, Aim 4 will generate functional insights into the molecular mechanism by which plant insulators shape the three-dimensional genome.

1 498 216 €

Start date: 2018-01-01, End date: 2022-12-31