Project acronym AGNOSTIC
Project Actively Enhanced Cognition based Framework for Design of Complex Systems
Researcher (PI) Björn Ottersten
Host Institution (HI) UNIVERSITE DU LUXEMBOURG
Call Details Advanced Grant (AdG), PE7, ERC-2016-ADG
Summary Parameterized mathematical models have been central to the understanding and design of communication, networking, and radar systems. However, they often lack the ability to model intricate interactions innate in complex systems. On the other hand, data-driven approaches do not need explicit mathematical models for data generation and have a wider applicability at the cost of flexibility. These approaches need labelled data, representing all the facets of the system interaction with the environment. With the aforementioned systems becoming increasingly complex with intricate interactions and operating in dynamic environments, the number of system configurations can be rather large leading to paucity of labelled data. Thus there are emerging networks of systems of critical importance whose cognition is not effectively covered by traditional approaches. AGNOSTIC uses the process of exploration through system probing and exploitation of observed data in an iterative manner drawing upon traditional model-based approaches and data-driven discriminative learning to enhance functionality, performance, and robustness through the notion of active cognition. AGNOSTIC clearly departs from a passive assimilation of data and aims to formalize the exploitation/exploration framework in dynamic environments. The development of this framework in three applications areas is central to AGNOSTIC. The project aims to provide active cognition in radar to learn the environment and other active systems to ensure situational awareness and coexistence; to apply active probing in radio access networks to infer network behaviour towards spectrum sharing and self-configuration; and to learn and adapt to user demand for content distribution in caching networks, drastically improving network efficiency. Although these cognitive systems interact with the environment in very different ways, sufficient abstraction allows cross-fertilization of insights and approaches motivating their joint treatment.
Summary
Parameterized mathematical models have been central to the understanding and design of communication, networking, and radar systems. However, they often lack the ability to model intricate interactions innate in complex systems. On the other hand, data-driven approaches do not need explicit mathematical models for data generation and have a wider applicability at the cost of flexibility. These approaches need labelled data, representing all the facets of the system interaction with the environment. With the aforementioned systems becoming increasingly complex with intricate interactions and operating in dynamic environments, the number of system configurations can be rather large leading to paucity of labelled data. Thus there are emerging networks of systems of critical importance whose cognition is not effectively covered by traditional approaches. AGNOSTIC uses the process of exploration through system probing and exploitation of observed data in an iterative manner drawing upon traditional model-based approaches and data-driven discriminative learning to enhance functionality, performance, and robustness through the notion of active cognition. AGNOSTIC clearly departs from a passive assimilation of data and aims to formalize the exploitation/exploration framework in dynamic environments. The development of this framework in three applications areas is central to AGNOSTIC. The project aims to provide active cognition in radar to learn the environment and other active systems to ensure situational awareness and coexistence; to apply active probing in radio access networks to infer network behaviour towards spectrum sharing and self-configuration; and to learn and adapt to user demand for content distribution in caching networks, drastically improving network efficiency. Although these cognitive systems interact with the environment in very different ways, sufficient abstraction allows cross-fertilization of insights and approaches motivating their joint treatment.
Max ERC Funding
2 499 595 €
Duration
Start date: 2017-10-01, End date: 2022-09-30
Project acronym BeStMo
Project Beyond Static Molecules: Modeling Quantum Fluctuations in Complex Molecular Environments
Researcher (PI) Alexandre TKATCHENKO
Host Institution (HI) UNIVERSITE DU LUXEMBOURG
Call Details Consolidator Grant (CoG), PE4, ERC-2016-COG
Summary We propose focused theory developments and applications, which aim to substantially advance our ability to model and understand the behavior of molecules in complex environments. From a large repertoire of possible environments, we have chosen to concentrate on experimentally-relevant situations, including molecular fluctuations in electric and optical fields, disordered molecular crystals, solvated (bio)molecules, and molecular interactions at/through low-dimensional nanostructures. A challenging aspect of modeling such realistic environments is that both molecular electronic and nuclear fluctuations have to be treated efficiently at a robust quantum-mechanical level of theory for systems with 1000s of atoms. In contrast, the current state of the art in the modeling of complex molecular systems typically consists of Newtonian molecular dynamics employing classical force fields. We will develop radically new approaches for electronic and nuclear fluctuations that unify concepts and merge techniques from quantum-mechanical many-body Hamiltonians, statistical mechanics, density-functional theory, and machine learning. Our developments will be benchmarked using experimental measurements with terahertz (THz) spectroscopy, atomic-force and scanning tunneling microscopy (AFM/STM), time-of-flight (TOF) measurements, and molecular interferometry.
Our final goal is to bridge the accuracy of quantum mechanics with the efficiency of force fields, enabling large-scale predictive quantum molecular dynamics simulations for complex systems containing 1000s of atoms, and leading to novel conceptual insights into quantum-mechanical fluctuations in large molecular systems. The project goes well beyond the presently possible applications and once successful will pave the road towards having a suite of first-principles-based modeling tools for a wide range of realistic materials, such as biomolecules, nanostructures, disordered solids, and organic/inorganic interfaces.
Summary
We propose focused theory developments and applications, which aim to substantially advance our ability to model and understand the behavior of molecules in complex environments. From a large repertoire of possible environments, we have chosen to concentrate on experimentally-relevant situations, including molecular fluctuations in electric and optical fields, disordered molecular crystals, solvated (bio)molecules, and molecular interactions at/through low-dimensional nanostructures. A challenging aspect of modeling such realistic environments is that both molecular electronic and nuclear fluctuations have to be treated efficiently at a robust quantum-mechanical level of theory for systems with 1000s of atoms. In contrast, the current state of the art in the modeling of complex molecular systems typically consists of Newtonian molecular dynamics employing classical force fields. We will develop radically new approaches for electronic and nuclear fluctuations that unify concepts and merge techniques from quantum-mechanical many-body Hamiltonians, statistical mechanics, density-functional theory, and machine learning. Our developments will be benchmarked using experimental measurements with terahertz (THz) spectroscopy, atomic-force and scanning tunneling microscopy (AFM/STM), time-of-flight (TOF) measurements, and molecular interferometry.
Our final goal is to bridge the accuracy of quantum mechanics with the efficiency of force fields, enabling large-scale predictive quantum molecular dynamics simulations for complex systems containing 1000s of atoms, and leading to novel conceptual insights into quantum-mechanical fluctuations in large molecular systems. The project goes well beyond the presently possible applications and once successful will pave the road towards having a suite of first-principles-based modeling tools for a wide range of realistic materials, such as biomolecules, nanostructures, disordered solids, and organic/inorganic interfaces.
Max ERC Funding
1 811 650 €
Duration
Start date: 2017-03-01, End date: 2022-02-28
Project acronym CLOUDMAP
Project Cloud Computing via Homomorphic Encryption and Multilinear Maps
Researcher (PI) Jean-Sebastien Coron
Host Institution (HI) UNIVERSITE DU LUXEMBOURG
Call Details Advanced Grant (AdG), PE6, ERC-2017-ADG
Summary The past thirty years have seen cryptography move from arcane to commonplace: Internet, mobile phones, banking system, etc. Homomorphic cryptography now offers the tantalizing goal of being able to process sensitive information in encrypted form, without needing to compromise on the privacy and security of the citizens and organizations that provide the input data. More recently, cryptographic multilinear maps have revolutionized cryptography with the emergence of indistinguishability obfuscation (iO), which in theory can been used to realize numerous advanced cryptographic functionalities that previously seemed beyond reach. However the security of multilinear maps is still poorly understood, and many iO schemes have been broken; moreover all constructions of iO are currently unpractical.
The goal of the CLOUDMAP project is to make these advanced cryptographic tasks usable in practice, so that citizens do not have to compromise on the privacy and security of their input data. This goal can only be achieved by considering the mathematical foundations of these primitives, working "from first principles", rather than focusing on premature optimizations. To achieve this goal, our first objective will be to better understand the security of the underlying primitives of multilinear maps and iO schemes. Our second objective will be to develop new approaches to significantly improve their efficiency. Our third objective will be to build applications of multilinear maps and iO that can be implemented in practice.
Summary
The past thirty years have seen cryptography move from arcane to commonplace: Internet, mobile phones, banking system, etc. Homomorphic cryptography now offers the tantalizing goal of being able to process sensitive information in encrypted form, without needing to compromise on the privacy and security of the citizens and organizations that provide the input data. More recently, cryptographic multilinear maps have revolutionized cryptography with the emergence of indistinguishability obfuscation (iO), which in theory can been used to realize numerous advanced cryptographic functionalities that previously seemed beyond reach. However the security of multilinear maps is still poorly understood, and many iO schemes have been broken; moreover all constructions of iO are currently unpractical.
The goal of the CLOUDMAP project is to make these advanced cryptographic tasks usable in practice, so that citizens do not have to compromise on the privacy and security of their input data. This goal can only be achieved by considering the mathematical foundations of these primitives, working "from first principles", rather than focusing on premature optimizations. To achieve this goal, our first objective will be to better understand the security of the underlying primitives of multilinear maps and iO schemes. Our second objective will be to develop new approaches to significantly improve their efficiency. Our third objective will be to build applications of multilinear maps and iO that can be implemented in practice.
Max ERC Funding
2 491 266 €
Duration
Start date: 2018-10-01, End date: 2023-09-30
Project acronym INTERACT
Project Intelligent Non-woven Textiles and Elastomeric Responsive materials by Advancing liquid Crystal Technology
Researcher (PI) Jan Peter Felix Lagerwall
Host Institution (HI) UNIVERSITE DU LUXEMBOURG
Call Details Consolidator Grant (CoG), PE8, ERC-2014-CoG
Summary A grand challenge in today’s materials research is the realization of flexible materials that are also intelligent and functional. They will be the enablers of true breakthroughs in the hot trends of soft robotics and wearable technology. The standard approach to the latter is to decorate rubber sheets with electronic components, yielding two serious flaws: rubber is uncomfortable as it does not breath and solid state electronics will eventually fail as a garment is flexed and stretched when worn. While the softness of rubber is ideal it must be used in the form of textile fibers to provide breathability, and for long-term failure resistance we need intelligent components that are soft. A solution to this conundrum was recently presented by the PI with the concept of liquid crystal (LC) electrospinning. The extreme responsiveness of LCs is transferred to a non-woven textile by incorporating the LC in the fiber core, yielding a smart flexible mat with sensory function. Moreover, it consumes no power, providing a further advantage over electronics-based approaches. In a second research line he uses microfluidics to make LC rubber microshells, functioning as autonomous actuators which may serve as innovative components for soft robotics, and photonic crystal shells. This interdisciplinary project presents an ambitious agenda to advance these new concepts to the realization of soft, stretchable intelligent materials of revolutionary character. Five specific objectives are in focus: 1) develop understanding of the dynamic response of LCs in these unconventional configurations; 2) establish interaction dynamics during polymerisation of an LC precursor; 3) elucidate LC response to gas exposure; 4) establish correlation between actuation response and internal order of curved LCE rubbers; and 5) assess usefulness of LC-functionalized fibers and polymerized LC shells, tubes and Janus particles in wearable sensors, soft robotic actuators and high-security identification tags.
Summary
A grand challenge in today’s materials research is the realization of flexible materials that are also intelligent and functional. They will be the enablers of true breakthroughs in the hot trends of soft robotics and wearable technology. The standard approach to the latter is to decorate rubber sheets with electronic components, yielding two serious flaws: rubber is uncomfortable as it does not breath and solid state electronics will eventually fail as a garment is flexed and stretched when worn. While the softness of rubber is ideal it must be used in the form of textile fibers to provide breathability, and for long-term failure resistance we need intelligent components that are soft. A solution to this conundrum was recently presented by the PI with the concept of liquid crystal (LC) electrospinning. The extreme responsiveness of LCs is transferred to a non-woven textile by incorporating the LC in the fiber core, yielding a smart flexible mat with sensory function. Moreover, it consumes no power, providing a further advantage over electronics-based approaches. In a second research line he uses microfluidics to make LC rubber microshells, functioning as autonomous actuators which may serve as innovative components for soft robotics, and photonic crystal shells. This interdisciplinary project presents an ambitious agenda to advance these new concepts to the realization of soft, stretchable intelligent materials of revolutionary character. Five specific objectives are in focus: 1) develop understanding of the dynamic response of LCs in these unconventional configurations; 2) establish interaction dynamics during polymerisation of an LC precursor; 3) elucidate LC response to gas exposure; 4) establish correlation between actuation response and internal order of curved LCE rubbers; and 5) assess usefulness of LC-functionalized fibers and polymerized LC shells, tubes and Janus particles in wearable sensors, soft robotic actuators and high-security identification tags.
Max ERC Funding
1 929 976 €
Duration
Start date: 2015-04-01, End date: 2020-03-31
Project acronym NanoThermo
Project Energy Conversion and Information Processing at Small Scales
Researcher (PI) Massimiliano Gennaro Esposito
Host Institution (HI) UNIVERSITE DU LUXEMBOURG
Call Details Consolidator Grant (CoG), PE3, ERC-2015-CoG
Summary Thermodynamics provided mankind with the intellectual tools to master energy transfers and energy conversion in macroscopic systems operating close to equilibrium. It is now one of the most fundamental theories in physics. My goal is to establish a thermodynamic theory describing energy conversion and information processing in small synthetic or biological systems operating far from equilibrium. Significant progress has been achieved in this direction over the last decade. The new theory is called stochastic thermodynamics (ST). It allows us to describe and understand energy conversion in systems as diverse as quantum junctions and molecular motors, and also to predict the energetic cost of information processing operations such as erasing bits of information or feedback controlling a small device. It was validated in single molecule pulling experiments, electronic circuits, NMR and colloidal particles in optical tweezers. Nevertheless, ST still suffers from serious limitations which prevent its application in more complex systems. Therefore, I propose to expand the theoretical foundations of ST far beyond its current realm of validity and to broaden the scope of its applications in various new directions. I want to answer questions such as: Can one design devices made of many small energy converters (e.g. thermoelectric junctions) arranged in such a way as to generate collective behaviors (e.g. synchronization) prompting higher powers and efficiencies? Can one do the same by engineer quantum effects? How can one reduce the dissipation occurring when computing very quickly with small devices? Why are metabolic networks so efficient in converting energy, transmitting information, and preventing errors (e.g. toxic byproducts)? I will do so in close contact with leading experimental groups in the field. My conviction is that ST will become as important for nanotechnologies and molecular biology as thermodynamics has been for the industrial revolution.
Summary
Thermodynamics provided mankind with the intellectual tools to master energy transfers and energy conversion in macroscopic systems operating close to equilibrium. It is now one of the most fundamental theories in physics. My goal is to establish a thermodynamic theory describing energy conversion and information processing in small synthetic or biological systems operating far from equilibrium. Significant progress has been achieved in this direction over the last decade. The new theory is called stochastic thermodynamics (ST). It allows us to describe and understand energy conversion in systems as diverse as quantum junctions and molecular motors, and also to predict the energetic cost of information processing operations such as erasing bits of information or feedback controlling a small device. It was validated in single molecule pulling experiments, electronic circuits, NMR and colloidal particles in optical tweezers. Nevertheless, ST still suffers from serious limitations which prevent its application in more complex systems. Therefore, I propose to expand the theoretical foundations of ST far beyond its current realm of validity and to broaden the scope of its applications in various new directions. I want to answer questions such as: Can one design devices made of many small energy converters (e.g. thermoelectric junctions) arranged in such a way as to generate collective behaviors (e.g. synchronization) prompting higher powers and efficiencies? Can one do the same by engineer quantum effects? How can one reduce the dissipation occurring when computing very quickly with small devices? Why are metabolic networks so efficient in converting energy, transmitting information, and preventing errors (e.g. toxic byproducts)? I will do so in close contact with leading experimental groups in the field. My conviction is that ST will become as important for nanotechnologies and molecular biology as thermodynamics has been for the industrial revolution.
Max ERC Funding
1 669 029 €
Duration
Start date: 2016-07-01, End date: 2021-06-30
Project acronym RealTCut
Project Towards real time multiscale simulation of cutting in non-linear materials
with applications to surgical simulation and computer guided surgery
Researcher (PI) Stéphane Pierre Alain Bordas
Host Institution (HI) UNIVERSITE DU LUXEMBOURG
Call Details Starting Grant (StG), PE8, ERC-2011-StG_20101014
Summary "Surgeons are trained as apprentices. Some conditions are rarely encountered and surgeons will only be trained in the specific skills associated with a given situation if they come across it. At the end of their residency, it is hoped that they will have faced sufficiently many cases to be competent. This can be dangerous to the patients.
If we were able to reproduce faithfully, in a virtual environment, the audio, visual and haptic experience of a surgeon as they prod, pull and incise tissue, then, surgeons would not have to train on cadavers, phantoms, or on the patients themselves.
Only a few researchers in the Computational Mechanics community have attacked the mechanical problems related to surgical simulation, so that mechanical faithfulness is not on par with audiovisual. This lack of fidelity in the reproduction of surgical acts such as cutting may explain why most surgeons who tested existing simulators report that the ""sensation"" fed back to them remains unrealistic. To date, the proposers are not aware of Computational Mechanics solutions addressing, at the same time, geometrical faithfulness, material realism, evolving cuts and quality control of the solution.
The measurable objectives for this research are as follows:
O1:Significantly alleviate the mesh generation and regeneration burden to represent organs’ geometries, underlying tissue microstructure and cuts with sufficient accuracy but minimal user intervention
O2:Move away from simplistic coarse-scale material models by deducing tissue rupture at the organ level from constitutive (e.g. damage) and contact models designed at the meso and micro scales
O3:Ensure real-time results through model order reduction coupled with the multi-scale fracture tools of O2
O4:Control solution accuracy and validate against a range of biomechanics problems including real-life brain surgery interventions with the available at our collaborators’"
Summary
"Surgeons are trained as apprentices. Some conditions are rarely encountered and surgeons will only be trained in the specific skills associated with a given situation if they come across it. At the end of their residency, it is hoped that they will have faced sufficiently many cases to be competent. This can be dangerous to the patients.
If we were able to reproduce faithfully, in a virtual environment, the audio, visual and haptic experience of a surgeon as they prod, pull and incise tissue, then, surgeons would not have to train on cadavers, phantoms, or on the patients themselves.
Only a few researchers in the Computational Mechanics community have attacked the mechanical problems related to surgical simulation, so that mechanical faithfulness is not on par with audiovisual. This lack of fidelity in the reproduction of surgical acts such as cutting may explain why most surgeons who tested existing simulators report that the ""sensation"" fed back to them remains unrealistic. To date, the proposers are not aware of Computational Mechanics solutions addressing, at the same time, geometrical faithfulness, material realism, evolving cuts and quality control of the solution.
The measurable objectives for this research are as follows:
O1:Significantly alleviate the mesh generation and regeneration burden to represent organs’ geometries, underlying tissue microstructure and cuts with sufficient accuracy but minimal user intervention
O2:Move away from simplistic coarse-scale material models by deducing tissue rupture at the organ level from constitutive (e.g. damage) and contact models designed at the meso and micro scales
O3:Ensure real-time results through model order reduction coupled with the multi-scale fracture tools of O2
O4:Control solution accuracy and validate against a range of biomechanics problems including real-life brain surgery interventions with the available at our collaborators’"
Max ERC Funding
1 343 955 €
Duration
Start date: 2012-01-01, End date: 2016-12-31
Project acronym TUNE
Project Testing the Untestable: Model Testing of Complex Software-Intensive Systems
Researcher (PI) Lionel, Claude, Laurent Briand
Host Institution (HI) UNIVERSITE DU LUXEMBOURG
Call Details Advanced Grant (AdG), PE6, ERC-2015-AdG
Summary Software-intensive systems pervade modern society and industry. These systems often play critical roles from an economic, safety or security standpoint, thus making their dependability indispensible. Software Verification and Validation (V&V) is core to ensuring software dependability. The most prevalent V&V technique is testing, that is the automated, systematic, and controlled execution of a system to detect faults or to show compliance with requirements. Increasingly, we are faced with systems that are untestable, meaning that traditional testing methods are highly expensive, time-consuming or infeasible to apply due to factors such as the systems’ continuous interactions with the environment and the deep intertwining of software with hardware.
TUNE will enable testing of untestable systems by revolutionising how we think about test automation. Our key idea is to frame testing on models rather than operational systems. We refer to such testing as model testing. The models that underlie model testing are executable representations of the relevant aspects of a system and its environment, alongside the risks of system failures. Such models inevitably have uncertainties due to complex, dynamic environment behaviours and the unknowns about the system. This necessitates that model testing be uncertainty-aware.
We propose to develop scalable, practical and uncertainty-aware techniques for test automation, leveraging our expertise on model-driven engineering and automated testing. Our solutions will synergistically combine metaheuristic search with system and risk models to drive the search for critical faults that entail the most risk. TUNE is the first initiative with the specific goal of raising the level of abstraction of testing from operational systems to models. The project will bring early and cost-effective automation to the testing of many critical systems that defy existing automation techniques, thus significantly improving the dependability of such systems.
Summary
Software-intensive systems pervade modern society and industry. These systems often play critical roles from an economic, safety or security standpoint, thus making their dependability indispensible. Software Verification and Validation (V&V) is core to ensuring software dependability. The most prevalent V&V technique is testing, that is the automated, systematic, and controlled execution of a system to detect faults or to show compliance with requirements. Increasingly, we are faced with systems that are untestable, meaning that traditional testing methods are highly expensive, time-consuming or infeasible to apply due to factors such as the systems’ continuous interactions with the environment and the deep intertwining of software with hardware.
TUNE will enable testing of untestable systems by revolutionising how we think about test automation. Our key idea is to frame testing on models rather than operational systems. We refer to such testing as model testing. The models that underlie model testing are executable representations of the relevant aspects of a system and its environment, alongside the risks of system failures. Such models inevitably have uncertainties due to complex, dynamic environment behaviours and the unknowns about the system. This necessitates that model testing be uncertainty-aware.
We propose to develop scalable, practical and uncertainty-aware techniques for test automation, leveraging our expertise on model-driven engineering and automated testing. Our solutions will synergistically combine metaheuristic search with system and risk models to drive the search for critical faults that entail the most risk. TUNE is the first initiative with the specific goal of raising the level of abstraction of testing from operational systems to models. The project will bring early and cost-effective automation to the testing of many critical systems that defy existing automation techniques, thus significantly improving the dependability of such systems.
Max ERC Funding
2 307 932 €
Duration
Start date: 2016-09-01, End date: 2021-08-31
Project acronym UpTEMPO
Project Ultrafast tunneling microscopy by optical field control of quantum currents
Researcher (PI) Daniele BRIDA
Host Institution (HI) UNIVERSITE DU LUXEMBOURG
Call Details Consolidator Grant (CoG), PE2, ERC-2018-COG
Summary The project aims at imaging electronic dynamics in molecules with atomic precision and sub-femtosecond temporal resolution. This result will be achieved by establishing new experiments at the boundary of ultrafast optics and scanning probe microscopy where the electric field of single-cycle light pulses is harnessed to control currents in nanojunctions. The basic concept relies on the fact that state-of-the-art femtosecond optical wave packets exhibit only one cycle of radiation with a defined electric field maximum. These pulses need to be phase locked to a “cosine-like” electric field profile. If such radiation is focused onto a junction with a nonlinear current-voltage characteristics, a net charge flow results solely due to the bias induced by the optical field.
In detail, we want to exploit the time resolution provided by this new technique and induce electron transport at the probe tip of a scanning tunneling microscope (STM). The optical control of the current over a sub-optical-cycle interval will guarantee a temporal resolution better that one femtosecond, thus improving by several orders of magnitude what can be achieved with standard electronic bias.
The core of the experimental system will be an ultrabroadband and passively phase-locked Er:fiber laser that is designed to generate single-cycle optical pulses in the near/mid-infrared, i.e. off resonant to the transition energies of III-V and II-VI semiconductors and large molecules. This laser will operate at 80-MHz repetition rate for enhanced sensitivity and stability when coupled to an ultra-high-vacuum STM. The setup will allow for the direct combination of independent pulse trains to resonantly excite few-femtosecond dynamics and then probe the electron density via the optically driven tunneling. In this pump-probe scheme it will be possible to map with atomic resolution the coherent evolution of electronic wavefunctions that in molecules and nanosystems follows an impulsive photoexcitation.
Summary
The project aims at imaging electronic dynamics in molecules with atomic precision and sub-femtosecond temporal resolution. This result will be achieved by establishing new experiments at the boundary of ultrafast optics and scanning probe microscopy where the electric field of single-cycle light pulses is harnessed to control currents in nanojunctions. The basic concept relies on the fact that state-of-the-art femtosecond optical wave packets exhibit only one cycle of radiation with a defined electric field maximum. These pulses need to be phase locked to a “cosine-like” electric field profile. If such radiation is focused onto a junction with a nonlinear current-voltage characteristics, a net charge flow results solely due to the bias induced by the optical field.
In detail, we want to exploit the time resolution provided by this new technique and induce electron transport at the probe tip of a scanning tunneling microscope (STM). The optical control of the current over a sub-optical-cycle interval will guarantee a temporal resolution better that one femtosecond, thus improving by several orders of magnitude what can be achieved with standard electronic bias.
The core of the experimental system will be an ultrabroadband and passively phase-locked Er:fiber laser that is designed to generate single-cycle optical pulses in the near/mid-infrared, i.e. off resonant to the transition energies of III-V and II-VI semiconductors and large molecules. This laser will operate at 80-MHz repetition rate for enhanced sensitivity and stability when coupled to an ultra-high-vacuum STM. The setup will allow for the direct combination of independent pulse trains to resonantly excite few-femtosecond dynamics and then probe the electron density via the optically driven tunneling. In this pump-probe scheme it will be possible to map with atomic resolution the coherent evolution of electronic wavefunctions that in molecules and nanosystems follows an impulsive photoexcitation.
Max ERC Funding
1 999 509 €
Duration
Start date: 2019-09-01, End date: 2024-08-31
