ERC FUNDED PROJECTS

The scientific goal of the proposal is to answer central questions related to diffeomorphism groups of manifolds of dimension 2 and 3, and to their deformation invariant analogs, the mapping class groups. While the classification of surfaces has been known for more than a century, their automorphism groups have yet to be fully understood. Even less is known about diffeomorphisms of 3-manifolds despite much interest, and the objects here have only been classified recently, by the breakthrough work of Perelman on the Poincar\'e and geometrization conjectures. In dimension 2, I will focus on the relationship between mapping class groups and topological conformal field theories, with applications to Hochschild homology. In dimension 3, I propose to compute the stable homology of classifying spaces of diffeomorphism groups and mapping class groups, as well as study the homotopy type of the space of diffeomorphisms. I propose moreover to establish homological stability theorems in the wider context of automorphism groups and more general families of groups. The project combines breakthrough methods from homotopy theory with methods from differential and geometric topology. The research team will consist of 3 PhD students, and 4 postdocs, which I will lead.

724 992 €

Start date: 2009-11-01, End date: 2014-10-31

The goal of 2D-TOPSENSE is to exploit the remarkable stretchability of two-dimensional semiconductors to fabricate optoelectronic devices where strain is used as an external knob to tune their properties. While bulk semiconductors tend to break under strains larger than 1.5%, 2D semiconductors (such as MoS2) can withstand deformations of up to 10-20% before rupture. This large breaking strength promises a great potential of 2D semiconductors as ‘straintronic’ materials, whose properties can be adjusted by applying a deformation to their lattice. In fact, recent theoretical works predicted an interesting physical phenomenon: a tensile strain-induced semiconductor-to-metal transition in 2D semiconductors. By tensioning single-layer MoS2 from 0% up to 10%, its electronic band structure is expected to undergo a continuous transition from a wide direct band-gap of 1.8 eV to a metallic behavior. This unprecedented large strain-tunability will undoubtedly have a strong impact in a wide range of optoelectronic applications such as photodetectors whose cut-off wavelength is tuned by varying the applied strain or atomically thin light modulators. To date, experimental works on strain engineering have been mostly focused on fundamental studies, demonstrating part of the potential of 2D semiconductors in straintronics, but they have failed to exploit strain engineering to add extra functionalities to optoelectronic devices. In 2D-TOPSENSE I will go beyond the state of the art in straintronics by designing and fabricating optoelectronic devices whose properties and performance can be tuned by means of applying strain. 2D-TOPSENSE will focus on photodetectors with a tunable bandwidth and detectivity, light emitting devices whose emission wavelength can be adjusted, light modulators based on 2D semiconductors such as transition metal dichalcogenides or black phosphorus and solar funnels capable of directing the photogenerated charge carriers towards a specific position.

1 930 437 €

Start date: 2018-03-01, End date: 2023-02-28

We propose to develop truly two-dimensional continuous materials and two-dimensional monolayer films composed of individual nanocrystals by the comparatively fast, inexpensive, and scalable colloidal synthesis method. The materials’ properties will be studied in detail, especially regarding their (photo-) electrical transport. This will allow developing new types of device structures, such as Coulomb blockade and field enhancement based transistors. Recently, we demonstrated the possibility to synthesize in a controlled manner truly two-dimensional colloidal nanostructures. We will investigate their formation mechanism, synthesize further materials as “nanosheets”, develop methodologies to tune their geometrical properties, and study their (photo-) electrical properties. Furthermore, we will use the Langmuir-Blodgett method to deposit highly ordered monolayers of monodisperse nanoparticles. Such structures show interesting transport properties governed by Coulomb blockade effects known from individual nanoparticles. This leads to semiconductor-like behavior in metal nanoparticle films. The understanding of the electric transport in such “multi-tunnel devices” is still very limited. Thus, we will investigate this concept in detail and take it to its limits. Beside improvement of quality and exchange of material we will tune the nanoparticles’ size and shape in order to gain a deeper understanding of the electrical properties of supercrystallographic assemblies. Furthermore, we will develop device concepts for diode and transistor structures which take into account the novel properties of the low-dimensional assemblies. Nanosheets and monolayers of nanoparticles truly follow the principle of building devices by the bottom-up approach and allow electric transport measurements in a 2D regime. Highly ordered nanomaterial systems possess easy and reliably to manipulate electronic properties what make them interesting for future (inexpensive) electronic devices.

1 497 200 €

Start date: 2013-02-01, End date: 2019-01-31

The field of C-H bond activation has evolved at an exponential pace in the last 15 years. What appeals most in those novel synthetic techniques is clear: they bypass the pre-activation steps usually required in traditional cross-coupling chemistry by directly metalating C-H bonds. Many C-H bond functionalizations today however, rely on poorly atom and step efficient oxidants, leading to significant and costly chemical waste, thereby seriously undermining the overall sustainability of those methods. As restrictions in sustainability regulations will further increase, and the cost of certain chemical commodities will rise, atom efficiency in organic synthesis remains a top priority for research. The aim of 2O2ACTIVATION is to develop novel technologies utilizing O2 as sole terminal oxidant in order to allow useful, extremely sustainable, thermodynamically challenging, dehydrogenative C-N and C-O bond forming coupling reactions. However, the moderate reactivity of O2 towards many catalysts constitutes a major challenge. 2O2ACTIVATION will pioneer the design of new catalysts based on the ultra-simple propene motive, capable of direct activation of O2 for C-H activation based cross-couplings. The project is divided into 3 major lines: O2 activation using propene and its analogues (propenoids), 1) without metal or halide, 2) with hypervalent halide catalysis, 3) with metal catalyzed C-H activation. The philosophy of 2O2ACTIVATION is to focus C-H functionalization method development on the oxidative event. Consequently, 2O2ACTIVATION breakthroughs will dramatically shortcut synthetic routes through the use of inactivated, unprotected, and readily available building blocks; and thus should be easily scalable. This will lead to a strong decrease in the costs related to the production of many essential chemicals, while preserving the environment (water as terminal by-product). The resulting novels coupling methods will thus have a lasting impact on the chemical industry.

1 489 823 €

Start date: 2017-03-01, End date: 2022-02-28

Membranes are key materials in our life. Nature offers high performance membranes relying on a parallel local regulation of nanopore structure, functional placement, membrane composition and architecture. Existing technological membranes are key materials in separation, recycling, sensing, energy conversion, being essential components for a sustainable future. But their performance is far away from their natural counterparts. One reason for this performance gap is the lack of 3D nanolocal control in membrane design. This applies to each individual nanopore but as well to the membrane architecture. This proposal aims to implement 3D printing (additive manufacturing, top down) and complex near-field and total internal reflection (TIR) high resolution microscopy induced polymer writing (bottom up) to nanolocally control in hierarchical nanoporous membranes spatially and independent of each other: porosity, pore functionalization, membrane architecture, composition. This disruptive technology platform will make accessible to date unachieved, highly accurate asymmetric nanopores and multifunctional, hierarchical membrane architecture/ composition and thus highly selective, directed, transport with tuneable rates. 3D-FNPWriting will demonstrate this for the increasing class of metal nanoparticle/ salt pollutants aiming for tuneable, selective, directed transport based monitoring and recycling instead of size-based filtration, accumulation into sewerage and distribution into nature. Specifically, the potential of this disruptive technology with respect to transport design will be demonstrated for a) a 3D-printed in-situ functionalized nanoporous fiber architecture and b) a printed, nanolocally near-field and TIR-microscopy polymer functionalized membrane representing a thin separation layer. This will open systematic understanding of nanolocal functional control on transport and new perspectives in water/ energy management for future smart industry/ homes.

1 499 844 €

Start date: 2019-04-01, End date: 2024-03-31

"Quantum information was born from the merging of classical information and quantum physics. Its main objective consists of understanding the quantum nature of information and learning how to process it by using physical systems which operate by following quantum mechanics laws. Quantum simulation is a fundamental instrument to investigate phenomena of quantum systems dynamics, such as quantum transport, particle localizations and energy transfer, quantum-to-classical transition, and even quantum improved computation, all tasks that are hard to simulate with classical approaches. Within this framework integrated photonic circuits have a strong potential to realize quantum information processing by optical systems. The aim of 3D-QUEST is to develop and implement quantum simulation by exploiting 3-dimensional integrated photonic circuits. 3D-QUEST is structured to demonstrate the potential of linear optics to implement a computational power beyond the one of a classical computer. Such ""hard-to-simulate"" scenario is disclosed when multiphoton-multimode platforms are realized. The 3D-QUEST research program will focus on three tasks of growing difficulty. A-1. To simulate bosonic-fermionic dynamics with integrated optical systems acting on 2 photon entangled states. A-2. To pave the way towards hard-to-simulate, scalable quantum linear optical circuits by investigating m-port interferometers acting on n-photon states with n>2. A-3. To exploit 3-dimensional integrated structures for the observation of new quantum optical phenomena and for the quantum simulation of more complex scenarios. 3D-QUEST will exploit the potential of the femtosecond laser writing integrated waveguides. This technique will be adopted to realize 3-dimensional capabilities and high flexibility, bringing in this way the optical quantum simulation in to new regime."

1 474 800 €

Start date: 2012-08-01, End date: 2017-07-31

Thermoelectrics (TEs) are important because they can convert heat directly into electrical energy and enable efficient heating/cooling. However, their popularization has been hindered by 1) their low efficiency (especially at room temperature), 2) the use of rare/toxic materials, and 3) the difficulty to process those materials. In 3DALIGN, I target a 3-in-1 solution to these challenges by using for the first time electric-field-assisted molecular alignment of 3D-printed TE polymers. High electrical/low thermal conductivity is required for efficient TEs, but both conductivities go hand in hand in traditional inorganic TE materials. This paradigm can shift for polymers, which possess complicated molecular structure. Despite their relatively low electrical conductivity, conducting polymers are appealing for TEs due to their much lower thermal conductivity than inorganic TE materials. Existing studies of organic TEs have focused on finding new materials, but no attention has been paid to molecular ordering, a known strategy to improve performance in organic transistors. I have recently developed a versatile method to induce molecular alignment in solution-processed polymers by using externally applied electric fields. In 3DALIGN, I propose to use this new method to boost the electrical conductivity of polymer TEs while inducing minimal alteration in their thermal conductivity. The high-risk of this goal is mitigated by other advantages of using polymer TEs: polymers are less toxic and more abundant than inorganic TE materials; and they are easy to 3D print, enabling a simple fabrication route for large-area through-plane TE structures that will lead to novel applications. In conclusion, this project will shed light in the relationship between molecular ordering and transport properties of organic electronic materials. If successful, it will also introduce a breakthrough in the performance and feasibility of TEs.

1 710 853 €

Start date: 2021-02-01, End date: 2026-01-31

I aim to develop an X-ray imaging technique capable of filming processes in 3D, with a temporal resolution several orders of magnitude faster than up-to-date 3D X-ray imaging techniques. The unique penetration power of X-rays allows us to study systems in their native environment. This property has led to the development of X-ray microtomography (µCT). µCT acquires 3D information, which determines the functionality and mechanical properties of nature, by rotating a sample with respect to the X-ray source. µCT is a crucial tool for several scientific disciplines such as physics, biology, and chemistry. Over the last decade, µCT has become a technique capable of not only recording 3D information but also filming dynamical processes. Several breakthroughs have made this possible: i) intense X-ray sources (synchrotron light sources), ii) efficient and fast X-ray detectors, and iii) fast 3D reconstruction algorithms. Despite all of these developments, the acquisition protocols remain unchanged, i.e., the sample is only rotated faster. This fast rotation introduces forces which may alter the studied dynamics and ultimately limit the achievable temporal resolution. My project is to establish an X-ray microscope that avoids the sample rotation, obtaining 3D information from a single X-ray flash by splitting it into nine-angularly resolved beams which illuminate the sample simultaneously. This approach, when implemented at intense X-ray sources such as synchrotron light sources and X-ray free-electron lasers, will allow the filming of natural processes with micrometer to nanometer resolution and resolve dynamics from microseconds to femtoseconds. To demonstrate its capabilities, I will study fundamental processes in cellulose fibers, a renewable biomaterial, which can replace fossil-based materials, such as plastics. This technique will open up the possibility to film dynamics in 3D to answer questions coming from industry and natural sciences at rates not accessible today.

1 999 213 €

Start date: 2021-03-01, End date: 2026-02-28

The focus of this project is the development of algorithms that allow one to capture and analyse dynamic events taking place in the real world. For this, we intend to develop smart camera networks that can perform a multitude of observation tasks, ranging from surveillance and tracking to high-fidelity, immersive reconstructions of important dynamic events (i.e. 4D videos). There are many fundamental questions in computer vision associated with these problems. Can the geometric, topologic and photometric properties of the camera network be obtained from live images? What is changing about the environment in which the network is embedded? How much information can be obtained from dynamic events that are observed by the network? What if the camera network consists of a random collection of sensors that happened to observe a particular event (think hand-held cell phone cameras)? Do we need synchronization? Those questions become even more challenging if one considers active camera networks that can adapt to the vision task at hand. How should resources be prioritized for different tasks? Can we derive optimal strategies to control camera parameters such as pan, tilt and zoom, trade-off resolution, frame-rate and bandwidth? More fundamentally, seeing cameras as points that sample incoming light rays and camera networks as a distributed sensor, how does one decide which rays should be sampled? Many of those issues are particularly interesting when we consider time-varying events. Both spatial and temporal resolution are important and heterogeneous frame-rates and resolution can offer advantages. Prior knowledge or information obtained from earlier samples can be used to restrict the possible range of solutions (e.g. smoothness assumption and motion prediction). My goal is to obtain fundamental answers to many of those question based on thorough theoretical analysis combined with practical algorithms that are proven on real applications.

1 757 422 €

Start date: 2008-08-01, End date: 2013-11-30