ERC FUNDED PROJECTS

One of the greatest challenges in exploiting the electron spin for information processing is that it is not a conserved quantity like the electron charge. In addition, spin lifetimes are rather short and correspondingly coherence is quickly lost. This challenge culminates in the coherent manipulation and detection of information from a single spin. Except in a few special systems, so far, single spins cannot be manipulated coherently on the atomic scale, while spin coherence times can only be measured on spin ensembles. A new concept is needed for coherence measurements on arbitrary single spins. Here, the principal investigator (PI) will combine a novel time- and spin-resolved low-temperature scanning tunneling microscope (STM) with the concept of pulsed electron paramagnetic resonance. With this unique and innovative setup, he will be able to address long-standing problems, such as relaxation and coherence times of arbitrary single spin systems on the atomic scale as well as individual spin interactions with the immediate surroundings. Spin readout will be realized through the detection of the absolute spin polarization in the tunneling current by a superconducting tip based on the Meservey-Tedrow-Fulde effect, which the PI has recently demonstrated for the first time in STM. For the coherent excitation, a specially designed pulsed GHz light source will be implemented. The goal is to better understand the spin dynamics and coherence times of single spin systems as well as the spin interactions involved in the decay mechanisms. This will have direct impact on the feasibility of quantum spin information processing with single spin systems on different decoupling surfaces and their scalability at the atomic level. A successful demonstration will enhance the detection limit of spins by several orders of magnitude and fill important missing links in the understanding of spin dynamics and quantum computing with single spins.

2 469 136 €

Start date: 2016-07-01, End date: 2022-06-30

A central problem in developmental biology is to understand how tissues are patterned in time and space - how do identical cells differentiate to form the adult body plan? Patterns often arise from prior asymmetries in developing embryos, but there is also increasing evidence for self-organizing mechanisms that can break the symmetry of an initially homogeneous cell population. These patterning processes are mediated by a small number of signaling molecules, including the TGF-β superfamily members BMP and Nodal. While we have begun to analyze how biophysical properties such as signal diffusion and stability contribute to axis formation and tissue allocation during vertebrate embryogenesis, three key questions remain. First, how does signaling cross-talk control robust patterning in developing tissues? Opposing sources of Nodal and BMP are sufficient to produce secondary zebrafish axes, but it is unclear how the signals interact to orchestrate this mysterious process. Second, how do signaling systems self-organize to pattern tissues in the absence of prior asymmetries? Recent evidence indicates that axis formation in mammalian embryos is independent of maternal and extra-embryonic tissues, but the mechanism underlying this self-organized patterning is unknown. Third, what are the minimal requirements to engineer synthetic self-organizing systems? Our theoretical analyses suggest that self-organizing reaction-diffusion systems are more common and robust than previously thought, but this has so far not been experimentally demonstrated. We will address these questions in zebrafish embryos, mouse embryonic stem cells, and bacterial colonies using a combination of quantitative imaging, optogenetics, mathematical modeling, and synthetic biology. In addition to providing insights into signaling and development, this high-risk/high-gain approach opens exciting new strategies for tissue engineering by providing asymmetric or temporally regulated signaling in organ precursors.

1 997 750 €

Start date: 2020-07-01, End date: 2025-06-30

The goal of this project is to demonstrate that novel aspects of the molecular basis of Darwinian adaptation can be discovered if the polygenic basis of adaptation is taken into account. This project will use the genome-wide distribution of cis-regulatory variants to discover the molecular pathways that are optimized during adaptation via accumulation of small effect mutations. Current approaches include scans for outlier genes with strong population genetics signatures of selection, or large effect QTL associating with fitness. They can only reveal a small subset of the molecular changes recruited along adaptive paths. Here, instead, the distribution of small effect mutations will be used to make inferences on the targets of polygenic adaptation across divergent populations in each of the two closely related species, A. thaliana and A. lyrata. These species are both found at diverse latitudes and show sign of local adaptation to climatic differences. Mutations affecting cis-regulation will be identified in leaves of plants exposed to various temperature regimes triggering phenotypic responses of adaptive relevance. Their distribution in clusters of functionally connected genes will be quantified. The phylogeographic differences in the distribution of the mutations will be used to disentangle neutral from adaptive clusters of functionally connected genes in each of the two species. This project will identify the molecular pathways subjected collectively to natural selection and provide a completely novel view on adaptive landscapes. It will further examine whether local adaptation occurs by convergent evolution of molecular systems in plants. This approach has the potential to find broad applications in ecology and agriculture.

1 683 120 €

Start date: 2015-09-01, End date: 2021-02-28

This ERC-CoG 2020 proposal, ALLOWE outlines a strategy for the development of low-valent aluminium systems through their synthesis, isolation, and reactivity investigation of neutral, ambiphilic, low-valent aluminium compounds, denoted “alumylenes”. Their dimeric form “dialumenes” featuring an aluminium-aluminium double bond will also be within the scope of the project. These low-valent aluminium species are expected to provide, along with greater understanding of the fundamental behaviour of low-valent aluminium, a varied and deep reactivity profile. These highly reactive compounds will offer a cheap, sustainable and non-toxic alternative to the current transition metal-based industrial chemical processes. The proposed scheme of work begins with the synthesis of neutral alumylenes and dialumenes, respectively. This will be achieved through the use of donor ligands (i.e. N-heterocyclic carbenes) and substituents with differing electronic and steric properties. With these compounds in hand, the reactivity towards small molecules will be investigated along with development of low-valent aluminium based catalysts. Furthermore, incorporation of transition metals into these aluminium systems will be targeted as these may possess unique and interesting properties. Established methodologies such as reductive dehalogenation or reductive dehydrohalogenation will provide access to novel low-valent aluminium compounds bearing bulky substituents and donor ligands. The synthetic portion of the work will also be supported by theoretical calculations. The outcome of ALLOWE will provide (i) in-depth insight and understanding into low-valent aluminium’s bonding nature, particularly emphasis laid on ambiphilic aluminium center (ii) plethora of striking reactivity towards transition metal free stoichiometric and catalytic activation of small molecules, and (iii) various potential applications in aluminium-based material chemistry.

1 997 750 €

Start date: 2021-06-01, End date: 2026-05-31