ERC FUNDED PROJECTS

How does the inside of the proton look like? What generates its spin?
3DSPIN will deliver essential information to answer these questions at the frontier of subnuclear physics. At present, we have detailed maps of the distribution of quarks and gluons in the nucleon in 1D (as a function of their momentum in a single direction). We also know that quark spins account for only about 1/3 of the spin of the nucleon. 3DSPIN will lead the way into a new stage of nucleon mapping, explore the distribution of quarks in full 3D momentum space and obtain unprecedented information on orbital angular momentum. Goals 1. extract from experimental data the 3D distribution of quarks (in momentum space), as described by Transverse-Momentum Distributions (TMDs); 2. obtain from TMDs information on quark Orbital Angular Momentum (OAM). Methodology 3DSPIN will implement state-of-the-art fitting procedures to analyze relevant experimental data and extract quark TMDs, similarly to global fits of standard parton distribution functions. Information about quark angular momentum will be obtained through assumptions based on theoretical considerations. The next five years represent an ideal time window to accomplish our goals, thanks to the wealth of expected data from deep-inelastic scattering experiments (COMPASS, Jefferson Lab), hadronic colliders (Fermilab, BNL, LHC), and electron-positron colliders (BELLE, BABAR). The PI has a strong reputation in this field. The group will operate in partnership with the Italian National Institute of Nuclear Physics and in close interaction with leading experts and experimental collaborations worldwide. Impact Mapping the 3D structure of chemical compounds has revolutionized chemistry. Similarly, mapping the 3D structure of the nucleon will have a deep impact on our understanding of the fundamental constituents of matter. We will open new perspectives on the dynamics of quarks and gluons and sharpen our view of high-energy processes involving nucleons.

1 509 000 €

Start date: 2015-07-01, End date: 2020-12-31

State-of-the-art microscopy and diffraction imaging provides insight into the atomic and sub-atomic structure of matter. They permit determination of the positions of atoms in a crystal lattice or in a molecule as well as the distribution of electrons inside atoms. State-of-the-art time-resolved spectroscopy with femtosecond and attosecond resolution provides access to dynamic changes in the atomic and electronic structure of matter. Our proposal aims at combining these two frontier techniques of XXI century science to make a long-standing dream of scientist come true: the direct observation of atoms and electrons in their natural state: in motion. Shifts in the atoms positions by tens to hundreds of picometers can make chemical bonds break apart or newly form, changing the structure and/or chemical composition of matter. Electronic motion on similar scales may result in the emission of light, or the initiation of processes that lead to a change in physical or chemical properties, or biological function. These motions happen within femtoseconds and attoseconds, respectively. To make them observable, we need a 4-dimensional (4D) imaging technique capable of recording freeze-frame snapshots of microscopic systems with picometer spatial resolution and femtosecond to attosecond exposure time. The motion can then be visualized by slow-motion replay of the freeze-frame shots. The goal of this project is to develop a 4D imaging technique that will ultimately offer picometer resolution is space and attosecond resolution in time.

2 500 000 €

Start date: 2010-03-01, End date: 2015-02-28

Several observed anomalies in neutrino oscillation data can be explained by a hypothetical fourth neutrino separated from the three standard neutrinos by a squared mass difference of a few eV2. This hypothesis can be tested with a PBq (ten kilocurie scale) 144Ce antineutrino beta-source deployed at the center of a large low background liquid scintillator detector, such like Borexino, KamLAND, and SNO+. In particular, the compact size of such a source could yield an energy-dependent oscillating pattern in event spatial distribution that would unambiguously determine neutrino mass differences and mixing angles. The proposed program aims to perform the necessary research and developments to produce and deploy an intense antineutrino source in a large liquid scintillator detector. Our program will address the definition of the production process of the neutrino source as well as its experimental characterization, the detailed physics simulation of both signal and backgrounds, the complete design and the realization of the thick shielding, the preparation of the interfaces with the antineutrino detector, including the safety and security aspects.

1 500 000 €

Start date: 2012-10-01, End date: 2018-09-30

What is the origin of cosmic rays, what are the dominant acceleration mechanisms in relativistic shocks, how do cosmic rays self-consistently influence the shock dynamics, how are relativistic collisionless shocks formed are longstanding scientific questions, closely tied to extreme plasma physics processes, and where a close interplay between the micro-instabilities and the global dynamics is critical. Relativistic shocks are closely connected with the propagation of intense streams of particles pervasive in many astrophysical scenarios. The possibility of exciting shocks in the laboratory will also be available very soon with multi-PW lasers or intense relativistic particle beams. Computational modeling is now established as a prominent research tool, by enabling the fully kinetic modeling of these systems for the first time. With the fast paced developments in high performance computing, the time is ripe for a focused research programme on simulation-based studies of relativistic shocks. This proposal therefore focuses on using self-consistent ab initio massively parallel simulations to study the physics of relativistic shocks, bridging the gap between the multidimensional microphysics of shock onset, formation, and propagation and the global system dynamics. Particular focus will be given to the shock acceleration mechanisms and the radiation signatures of the various physical processes, with the goal of solving some of the central questions in plasma/relativistic phenomena in astrophysics and in the laboratory, and opening new avenues between theoretical/massive computational studies, laboratory experiments and astrophysical observations.

1 588 800 €

Start date: 2011-06-01, End date: 2016-07-31

"An important driver of scientific progress has always been the envisioning of applications far beyond existing technological capabilities. Such thinking creates new challenges for physicists, driven by the groundbreaking nature of the anticipated application. In the case of laser physics, one of these applications is laser wake-field particle acceleration and possible future uses thereof, such as in collider experiments, or for medical applications such as cancer treatment. To accelerate electrons and positrons to TeV-energies, a laser architecture is required that allows for the combination of high efficiency, Petawatt peak powers, and Megawatt average powers. Developing such a laser system would be a challenging task that might take decades of aggressive research, development, and, most important, revolutionary approaches and innovative ideas. The goal of the ACOPS project is to develop a compact, efficient, scalable, and cost-effective high-average and high-peak power ultra-short pulse laser concept. The proposed approach to this goal relies on the spatially and temporally separated amplification of ultrashort laser pulses in waveguide structures, followed by coherent combination into a single train of pulses with increased average power and pulse energy. This combination can be realized through the coherent addition of the output beams of spatially separated amplifiers, combined with the pulse stacking of temporally separated pulses in passive enhancement cavities, employing a fast-switching element as cavity dumper. Therefore, the three main tasks are the development of kW-class high-repetition-rate driving lasers, the investigation of non-steady state pulse enhancement in passive cavities, and the development of a suitable dumping element. If successful, the proposed concept would undoubtedly provide a tool that would allow researchers to surpass the current limits in high-field physics and accelerator science."

1 881 040 €

Start date: 2014-02-01, End date: 2019-01-31

"The proposed research program has three main objectives. The first and second objectives are to seek extreme precisions in optical atomic spectroscopy and optical clocks, and to use this quest as a mean of exploration in atomic physics. The third objective is to explore new possibilities that stem from extreme precision. These goals will be pursued via three complementary activities: #1: Search for extreme precisions with an Hg optical lattice clock. #2: Explore and exploit the rich Hg system, which is essentially unexplored in the cold and ultra-cold regime. #3: Identify new applications of clocks with extreme precision to Earth science. Clocks can measure directly the gravitational potential via Einstein’s gravitational redshift, leading to the idea of “clock-based geodesy”. The 2 first activities are experimental and build on an existing setup, where we demonstrated the feasibility of an Hg optical lattice clock. Hg is chosen for its potential to surpass competing systems. We will investigate the unexplored physics of the Hg clock. This includes interactions between Hg atoms, lattice-induced light shifts, and sensitivity to external fields which are specific to the atomic species. Beyond, we will explore the fundamental limits of the optical lattice scheme. We will exploit other remarkable features of Hg associated to the high atomic number and the diversity of stable isotopes. These features enable tests of fundamental physical laws, ultra-precise measurements of isotope shifts, measurement of collisional properties toward evaporative cooling and quantum gases of Hg, investigation of forbidden transitions promising for measuring the nuclear anapole moment of Hg. The third activity is theoretical and is aimed at initiating collaborations with experts in modelling Earth gravity. With this expertise, we will identify the most promising and realistic approaches for clocks and emerging remote comparison methods to contribute to geodesy, hydrology, oceanography, etc."

1 946 432 €

Start date: 2014-04-01, End date: 2019-03-31

Fundamental interactions in nature are well described by quantum gauge fields in 4 space-time dimensions (4d). When the strength of gauge interaction is weak the Feynman perturbation techniques are very efficient for the description of most of the experimentally observable consequences of the Standard model and for the study of high energy processes in QCD. But in the intermediate and strong coupling regime, such as the relatively small energies in QCD, the perturbation theory fails leaving us with no reliable analytic methods (except the Monte-Carlo simulation). The project aims at working out new analytic and computational methods for strongly coupled gauge theories in 4d. We will employ for that two important discoveries: 1) the gauge-string duality (AdS/CFT correspondence) relating certain strongly coupled gauge Conformal Field Theories to the weakly coupled string theories on Anty-deSitter space; 2) the solvability, or integrability of maximally supersymmetric (N=4) 4d super Yang-Mills (SYM) theory in multicolor limit. Integrability made possible pioneering exact numerical and analytic results in the N=4 multicolor SYM at any coupling, effectively summing up all 4d Feynman diagrams. Recently, we conjectured a system of functional equations - the AdS/CFT Y-system – for the exact spectrum of anomalous dimensions of all local operators in N=4 SYM. The conjecture has passed all available checks. My project is aimed at the understanding of origins of this, still mysterious integrability. Deriving the AdS/CFT Y-system from the first principles on both sides of gauge-string duality should provide a long-awaited proof of the AdS/CFT correspondence itself. I plan to use the Y-system to study the systematic weak and strong coupling expansions and the so called BFKL limit, as well as for calculation of multi-point correlation functions of N=4 SYM. We hope on new insights into the strong coupling dynamics of less supersymmetric gauge theories and of QCD.

1 456 140 €

Start date: 2013-11-01, End date: 2018-10-31

AGEnTh is an interdisciplinary proposal which aims at theoretically investigating atomic many-body systems (cold atoms and trapped ions) in close connection to concepts from quantum information, condensed matter, and high energy physics. The main goals of this programme are to: I) Find to scalable schemes for the measurements of entanglement properties, and in particular entanglement spectra, by proposing a shifting paradigm to access entanglement focused on entanglement Hamiltonians and field theories instead of probing density matrices; II) Show how atomic gauge theories (including dynamical gauge fields) are ideal candidates for the realization of long-sought, highly-entangled states of matter, in particular topological superconductors supporting parafermion edge modes, and novel classes of quantum spin liquids emerging from clustering; III) Develop new implementation strategies for the realization of gauge symmetries of paramount importance, such as discrete and SU(N)xSU(2)xU(1) groups, and establish a theoretical framework for the understanding of atomic physics experiments within the light-from-chaos scenario pioneered in particle physics. These objectives are at the cutting-edge of fundamental science, and represent a coherent effort aimed at underpinning unprecedented regimes of strongly interacting quantum matter by addressing the basic aspects of probing, many-body physics, and implementations. The results are expected to (i) build up and establish qualitatively new synergies between the aforementioned communities, and (ii) stimulate an intense theoretical and experimental activity focused on both entanglement and atomic gauge theories. In order to achieve those, AGEnTh builds: (1) on my background working at the interface between atomic physics and quantum optics from one side, and many-body theory on the other, and (2) on exploratory studies which I carried out to mitigate the conceptual risks associated with its high-risk/high-gain goals.

1 055 317 €

Start date: 2018-05-01, End date: 2023-04-30

In quantum electrodynamics a range of fundamental processes are driven by omnipresent vacuum fluctuations. Photonic crystals can control vacuum fluctuations and thereby the fundamental interaction between light and matter. We will conduct experiments on quantum dots in photonic crystals and observe novel quantum electrodynamics effects including fractional decay and the modified Lamb shift. Furthermore, photonic crystals will be explored for shielding sensitive quantum-superposition states against decoherence. Defects in photonic crystals allow novel functionalities enabling nanocavities and waveguides. We will use the tight confinement of light in a nanocavity to entangle a quantum dot and a photon, and explore the scalability. Controlled ways of generating scalable and robust quantum entanglement is the essential missing link limiting quantum communication and quantum computing. A single quantum dot coupled to a slowly propagating mode in a photonic crystal waveguide will be used to induce large nonlinearities at the few-photon level. Finally we will explore a novel route to enhanced light-matter interaction employing controlled disorder in photonic crystals. In disordered media multiple scattering of light takes place and can lead to the formation of Anderson-localized modes. We will explore cavity quantum electrodynamics in Anderson-localized random cavities considering disorder a resource and not a nuisance, which is the traditional view. The main focus of the project will be on optical experiments, but fabrication of photonic crystals and detailed theory will be carried out as well. Several of the proposed experiments will constitute milestones in quantum optics and may pave the way for all-solid-state quantum communication with quantum dots in photonic crystals.

1 199 648 €

Start date: 2010-12-01, End date: 2015-11-30

The field of disordered quantum gases is developing rapidly. Dramatic progress has been achieved recently and first experimental observation of one-dimensional Anderson localization (AL) of matterwaves has been reported using Bose-Einstein condensates in controlled disorder (in our group at Institut d'Optique and at LENS; Nature, 2008). This dramatic success results from joint theoretical and experimental efforts, we have contributed to. Most importantly, it opens unprecedented routes to pursue several outstanding challenges in the multidisciplinary field of disordered systems, which, after fifty years of Anderson localization, is more active than ever. This theoretical project aims at further developing the emerging field of disordered quantum gases towards novel challenges. Our aim is twofold. First, we will propose and analyze schemes where experiments on ultracold atoms can address unsolved issues: AL in dimensions higher than one, effects of inter-atomic interactions on AL, strongly-correlated disordered gases and quantum simulators for spin systems (spin glasses). Second, by taking into account specific features of ultracold atoms, beyond standard toy-models, we will raise and study new questions which have not been addressed before (eg long-range correlations of speckle potentials, finite-size effects, controlled interactions). Both aspects would open new frontiers to disordered quantum gases and offer new possibilities to shed new light on highly debated issues. Our main concerns are thus to (i) study situations relevant to experiments, (ii) develop new approaches, applicable to ultracold atoms, (iii) identify key observables, and (iv) propose new challenging experiments. In this project, we will benefit from the original situation of our theory team: It is independent but forms part of a larger group (lead by A. Aspect), which is a world-leader in experiments on disordered quantum gases, we have already developed close collaborative relationship with.

985 200 €

Start date: 2011-01-01, End date: 2015-12-31

This project focuses on developing quantum field theory methods and applying them to the phenomenology of elementary particles. At the Large Hadron Collider (LHC) our current best theoretical understanding of particle physics is being tested against experiment by measuring e.g. properties of the recently discovered Higgs boson. With run two of the LHC, currently underway, the experimental accuracy will further increase. Theoretical predictions matching the latter are urgently needed. Obtaining these requires extremely difficult calculations of scattering amplitudes and cross sections in quantum field theory, including calculations to correctly describe large contributions due to long-distance physics in the latter. Major obstacles in such computations are the large number of Feynman diagrams that are difficult to handle, even with the help of modern computers, and the computation of Feynman loop integrals. To address these issues, we will develop innovative methods that are inspired by new structures found in supersymmetric field theories. We will extend the scope of the differential equations method for computing Feynman integrals, and apply it to scattering processes that are needed for phenomenology, but too complicated to analyze using current methods. Our results will help measure fundamental parameters of Nature, such as, for example, couplings of the Higgs boson, with unprecedented precision. Moreover, by accurately predicting backgrounds from known physics, our results will also be invaluable for searches of new particles.

2 000 000 €

Start date: 2017-10-01, End date: 2023-09-30

I propose to use large clouds of cold Ytterbium atoms to observe Anderson localization of light in three dimensions, which has challenged theoreticians and experimentalists for many decades. After the prediction by Anderson of a disorder-induced conductor to insulator transition for electrons, light has been proposed as ideal non interacting waves to explore coherent transport properties in the absence of interactions. The development in experiments and theory over the past several years have shown a route towards the experimental realization of this phase transition. Previous studies on Anderson localization of light using semiconductor powders or dielectric particles have shown that intrinsic material properties, such as absorption or inelastic scattering of light, need to be taken into account in the interpretation of experimental signatures of Anderson localization. Laser-cooled clouds of atoms avoid the problems of samples used so far to study Anderson localization of light. Ab initio theoretical models, available for cold Ytterbium atoms, have shown that the mere high spatial density of the scattering sample is not sufficient to allow for Anderson localization of photons in three dimensions, but that an additional magnetic field or additional disorder on the level shifts can induce a phase transition in three dimensions. The role of disorder in atom-light interactions has important consequences for the next generation of high precision atomic clocks and quantum memories. By connecting the mesoscopic physics approach to quantum optics and cooperative scattering, this project will allow better control of cold atoms as building blocks of future quantum technologies. Time-resolved transport experiments will connect super- and subradiant assisted transmission with the extended and localized eigenstates of the system. Having pioneered studies on weak localization and cooperative scattering enables me to diagnostic strong localization of light by cold atoms.

2 490 717 €

Start date: 2019-10-01, End date: 2024-09-30

The ability of positrons to annihilate with electrons, producing characteristic gamma rays, gives them important use in medicine via positron-emission tomography (PET), diagnostics of industrially-important materials, and in elucidating astrophysical phenomena. Moreover, the fundamental interactions of positrons and positronium (Ps) with atoms, molecules and condensed matter are currently under intensive study in numerous international laboratories, to illuminate collision phenomena and perform precision tests of fundamental laws. Proper interpretation and development of these costly and difficult experiments requires accurate calculations of low-energy positron and Ps interactions with normal matter. These systems, however, involve strong correlations, e.g., polarisation of the atom and virtual-Ps formation (where an atomic electron tunnels to the positron): they significantly effect positron- and Ps-atom/molecule interactions, e.g., enhancing annihilation rates by many orders of magnitude, and making the accurate description of these systems a challenging many-body problem. Current theoretical capability lags severely behind that of experiment. Major theoretical and computational developments are required to bridge the gap. One powerful method, which accounts for the correlations in a natural, transparent and systematic way, is many-body theory (MBT). Building on my expertise in the field, I propose to develop new MBT to deliver unique and unrivalled capability in theory and computation of low-energy positron and Ps interactions with atoms, molecules, and condensed matter. The ambitious programme will provide the basic understanding required to interpret and develop the fundamental experiments, antimatter-based materials science techniques, and wider technologies, e.g., (PET), and more broadly, potentially revolutionary and generally applicable computational methodologies that promise to define a new level of high-precision in atomic-MBT calculations.

1 318 419 €

Start date: 2019-02-01, End date: 2024-01-31

This project enters the experimental investigation of anyonic quantum gases. We will study anyons – conjectured particles with a statistical exchange phase anywhere between 0 and π – in different many-body systems. This progress will be enabled by a unique approach of bringing together artificial gauge fields and quantum gas microscopes for ultracold atoms. Specifically, we will implement the 1D anyon Hubbard model via a lattice shaking protocol that imprints density-dependent Peierls phases. By engineering the statistical exchange phase, we can continuously tune between bosons and fermions and explore a statistically-induced quantum phase transition. We will monitor the continuous fermionization via the build-up of Friedel oscillations. Using state-of-the-art cold atom technology, we will thus open the physics of anyons to experimental research and address open questions related to their fractional exclusion statistics. Secondly, we will create fractional quantum Hall systems in rapidly rotating microtraps. Using the quantum gas microscope, we will i) control the optical potentials at a level which allows approaching the centrifugal limit and ii) use small atom numbers equal to the inserted angular momentum quantum number. The strongly-correlated ground states such as the Laughlin state can be identified via their characteristic density correlations. Of particular interest are the quasihole excitations, whose predicted anyonic exchange statistics have not been directly observed to date. We will probe and test their statistics via the characteristic counting sequence in the excitation spectrum. Furthermore, we will test ideas to transfer anyonic properties of the excitations to a second tracer species. This approach will enable us to both probe the fractional exclusion statistics of the excitations and to create a 2D anyonic quantum gas. In the long run, these techniques open a path to also study non-Abelian anyons with ultracold atoms.

1 497 500 €

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

The goal of this project is to prepare in a deterministic way, and then to characterize, various entangled states of up to 25 individual atoms held in an array of optical tweezers. Such a system provides a new arena to explore quantum entangled states of a large number of particles. Entanglement is the existence of quantum correlations between different parts of a system, and it is recognized as an essential property that distinguishes the quantum and the classical worlds. It is also a resource in various areas of physics, such as quantum information processing, quantum metrology, correlated quantum systems and quantum simulation. In the proposed design, each site is individually addressable, which enables single atom manipulation and detection. This will provide the largest entangled state ever produced and fully characterized at the individual particle level. The experiment will be implemented by combining two crucial novel features, that I was able to demonstrate very recently: first, the manipulation of quantum bits written on long-lived hyperfine ground states of single ultra-cold atoms trapped in microscopic optical tweezers; second, the generation of entanglement by using the strong long-range interactions between Rydberg states. These interactions lead to the so-called dipole blockade , and enable the preparation of various classes of entangled states, such as states carrying only one excitation (W states), and states analogous to Schrödinger s cats (GHZ states). Finally, I will also explore strategies to protect these states against decoherence, developed in the framework of fault-tolerant and topological quantum computing. This project therefore combines an experimental challenge and the exploration of entanglement in a mesoscopic system.

1 449 600 €

Start date: 2009-12-01, End date: 2014-11-30

Physical systems featuring strong electronic correlations exhibit fascinating phenomena, as exemplified by high-Tc superconductivity, quantum magnetism or fractional quantum Hall physics. Inspired by these effects, new ideas have emerged to harness strongly correlated phases in artificial quantum materials, and use them as a resource for fundamental science and for quantum technology. Promising approaches for producing quantum devices are found in condensed matter platforms: one can indeed benefit from nanofabrication to engineer systems that are compact, versatile, and which can potentially be integrated in large-scale architectures. The main goal of ARQADIA is to engineer and study quantum correlated and topological phases of light using artificial photonic materials that I will fabricate in a solid-state platform. I will use exciton-polaritons in semiconductor microcavities, which are hybrid quasiparticles resulting from strong coupling between cavity photons and quantum well excitons. Polaritons are particularly attractive since they combine the best of two worlds: (i) through their photon component, they can be confined in microstrucutres and manipulated using optical spectroscopy; (ii) through their matter component, interactions between polaritons can be tuned and reinforced. Moreover, polaritons can be detected through the decay of cavity photons, which means that they naturally implement out-of-equilibrium physics and allow addressing fascinating questions related to the interplay between quantum correlations and dissipation. Within ARQADIA, I will tackle the challenge of engineering quantum correlations between polaritons via a technological breakthrough: I will insert active materials featuring strongly interacting excitons in microcavity lattices. I will use these materials to study out-of-equilibrium strongly correlated phases in vastly different regimes: from 1D to 2D, from weakly to strongly interacting and from topologically trivial to non-trivial.

1 499 603 €

Start date: 2021-01-01, End date: 2025-12-31

The main goal of ASTRUm is to employ stored and cooled radioactive ions for forefront nuclear astrophysics research. Four key experiments are proposed to be conducted at GSI in Darmstadt, which holds the only facility to date capable of storing highly charged radionuclides in the required element and energy range. The proposed experiments can hardly be conducted by any other technique or method. The weak decay matrix element for the transition between the 2.3 keV state in 205Pb and the ground state of 205Tl will be measured via the bound state beta decay measurement of fully ionized 205Tl81+. This will provide the required data to determine the solar pp-neutrino flux integrated over the last 5 million years and will allow us to unveil the astrophysical conditions prior to the formation of the solar system. The measurements of the alpha-decay width of the 4.033 MeV excited state in 19Ne will allow us to constrain the conditions for the ignition of the rp-process in X-ray bursters. ASTRUm will open a new field by enabling for the first time measurements of proton- and alpha-capture reaction cross-sections on radioactive nuclei of interest for the p-process of nucleosynthesis. Last but not least, broad band mass and half-life measurements in a ring is the only technique to precisely determine these key nuclear properties for nuclei with half-lives as short as a millisecond and production rates of below one ion per day. To accomplish these measurements with highest efficiency, sensitivity and precision, improved detector systems will be developed within ASTRUm. Possible applications of these systems go beyond ASTRUm objectives and will be used in particular in accelerator physics. The instrumentation and experience gained within ASTRUm will be indispensable for planning the future, next generation storage ring projects, which are launched or proposed at several radioactive ion beam facilities.

1 874 750 €

Start date: 2016-04-01, End date: 2021-09-30

Gauge theories play a central role in particle and condensed matter physics. Heavy-ion collisions explore the strong dynamics of quarks and gluons, which also governs the deep interior of neutron stars, while strongly correlated electrons determine the physics of high-temperature superconductors and spin liquids. Numerical simulations of such systems are often hindered by sign problems. In quantum link models - an alternative formulation of gauge theories developed by the applicant - gauge fields emerge from discrete quantum variables. In the past year, in close collaboration with atomic physicists, we have established quantum link models as a framework for the atomic quantum simulation of dynamical gauge fields. Abelian gauge theories can be realized with Bose-Fermi mixtures of ultracold atoms in an optical lattice, while non-Abelian gauge fields arise from fermionic constituents embodied by alkaline-earth atoms. Quantum simulators, which do not suffer from the sign problem, shall be constructed to address non-trivial dynamics, including quantum phase transitions in spin liquids, the real-time dynamics of confining strings as well as of chiral symmetry restoration at finite temperature and baryon density, baryon superfluidity, or color-flavor locking. New classical simulation algorithms shall be developed in order to solve severe sign problems, to investigate confining gauge theories, and to validate the proposed quantum simulators. Starting from U(1) and SU(2) gauge theories, an atomic physics tool box shall be developed for quantum simulation of gauge theories of increasing complexity, ultimately aiming at 4-d Quantum Chromodynamics (QCD). This project is based on innovative ideas from particle, condensed matter, and computational physics, and requires an interdisciplinary team of researchers. It has the potential to drastically increase the power of simulations and to address very challenging problems that cannot be solved with classical simulation methods.

1 975 242 €

Start date: 2014-02-01, End date: 2019-01-31

The astrophysical p-process, the stellar production mechanism of the heavy, proton rich isotopes (p-isotopes), is one of the least studied processes in nucleosynthesis. The astrophysical site(s) for the p-process could not yet be clearly identified. In order to reproduce the natural abundances of the p-isotopes, the p-process models must take into account a huge nuclear reaction network. A precise knowledge of the rate of the nuclear reactions in this network is essential for a reliable abundance calculation and for a clear assignment of the astrophysical site(s). For lack of experimental data the nuclear physics inputs for the reaction networks are based on statistical model calculations. These calculations are largely untested in the mass and energy range relevant to the p-process and the uncertainties in the reaction rate values result in a correspondingly uncertain prediction of the p-isotope abundances. Therefore, experiments aiming at the determination of reaction rates for the p-process are of great importance. In this project nuclear reaction cross section measurements will be carried out in the mass and energy range of p-process to check the reliability of the statistical model calculations and to put the p-process models on a more reliable base. The accelerators of the Institute of Nuclear Research in Debrecen, Hungary provide the necessary basis for such studies. The p-process model calculations are especially sensitive to the rates of reactions involving alpha particles and heavy nuclei. Because of technical difficulties, so far there are practically no experimental data available on such reactions and the uncertainty in these reaction rates is presently one of the biggest contributions to the uncertainty of p-isotope abundance calculations. With the help of the ERC grant the alpha-induced reaction cross sections can be measured on heavy isotopes for the first time, which could contribute to a better understanding of the astrophysical p-process.

750 000 €

Start date: 2008-07-01, End date: 2013-06-30

Coherence is a fundamental property of quantum mechanics, characterizing phase correlations of light or matter waves. It is at the heart of many physical phenomena, such as the creation of electron-hole pairs in the photovoltaic effect or the fast migration of electronic charge within a molecule. In order to study coherent electron dynamics, extremely high spatial and temporal resolving power is required, which is highly challenging. Well-established imaging methods like scanning tunneling microscopy achieve atomic-scale spatial resolution, while lacking ultrafast time resolution. At the temporal frontier, I recently bridged the gap between attosecond spectroscopy (1as = 10-18 s) and the nano-scale. The goal of my research program is to unlock the full potential of attosecond spectroscopy by achieving simultaneous spatial and temporal probing of ultrafast coherent phenomena. The proposed approach relies on the introduction of attosecond spectroscopy into scanning tunneling microscopy and electron holography. The spatial resolution of these methods is based on nano-scale needle tips, serving as local probes or as point-like electron sources. My team and I will develop attosecond temporal gates at the tips, enabling pump-probe spectroscopy. The resulting “pump” – triggering the coherent dynamics – and the “probe” – measuring its evolution – are localized in space and time, with attosecond and sub-nanometer precision. This combination will allow watching charge dynamics in a single molecule and observing multi-electron dynamics in nanostructures with atomic-scale site selectivity, as they evolve in real time. My approach has the potential to shed new light on quantum optics, plasmonics, molecular electronics, surface science and femtochemistry. In particular, my team and I will study quantum tunneling on the atomic level, charge migration in organic molecules and electron-hole dynamics in low-dimensional solid-state systems.

1 690 323 €

Start date: 2020-01-01, End date: 2024-12-31

By enabling the conversion of forces into measurable displacements, mechanical oscillators have always played a central role in experimental physics. Recent developments in the PI group demonstrated the possibility to realize ultrasensitive and vectorial force field sensing by using suspended SiC nanowires and optical readout of their transverse vibrations. Astonishing sensitivities were obtained at room and dilution temperatures, at the Atto- Zepto-newton level, for which the electron-electron interaction becomes detectable at 100µm. The goal of the project is to push forward those ultrasensitive nano-optomechanical force sensors, to realize even more challenging explorations of novel fundamental interactions at the quantum-classical interface. We will develop universal advanced sensing protocols to explore the vectorial structure of fundamental optical, electrostatic or magnetic interactions, and investigate Casimir force fields above nanostructured surfaces, in geometries where it was recently predicted to become repulsive. The second research axis is the one of cavity nano-optomechanics: inserting the ultrasensitive nanowire in a high finesse optical microcavity should enhance the light-nanowire interaction up to the point where a single cavity photon can displace the nanowire by more than its zero point quantum fluctuations. We will investigate this so-called ultrastrong optomechanical coupling regime, and further explore novel regimes in cavity optomechanics, where optical non-linearities at the single photon level become accessible. The last part is dedicated to the exploration of hybrid qubit-mechanical systems, in which nanowire vibrations are magnetically coupled to the spin of a single Nitrogen Vacancy defect in diamond. We will focus on the exploration of spin-dependent forces, aiming at mechanically detecting qubit excitations, opening a novel road towards the generation of non-classical states of motion, and mechanically enhanced quantum sensors.

2 067 905 €

Start date: 2019-09-01, End date: 2024-08-31

Collective electron motion can unfold on attosecond time scales in nanoplasmonic systems, as defined by the inverse spectral bandwidth of the plasmonic resonant region. Similarly, in dielectrics or semiconductors, the laser-driven collective motion of electrons can occur on this characteristic time scale. Until now, such collective electron dynamics has not been directly observed on its natural, attosecond timescale. In ATTOCO, the attosecond, sub-cycle dynamics of strong-field driven collective electron dynamics in clusters and nanoparticles will be explored. Moreover, we will explore field-dependent processes induced by strong laser fields in nanometer sized matter, such as the metallization of dielectrics, which has been recently proposed theoretically. In order to map the collective electron motion we will apply the attosecond nanoplasmonic streaking technique, which has been proposed and developed theoretically. In this approach, the temporal resolution is achieved by limiting the emission of high energetic, direct photoelectrons to a sub-cycle time window using attosecond XUV pulses phase-locked to a driving few-cycle near-infrared field. Kinetic energy spectra of the photoelectrons recorded for different delays between the excitation field and the ionizing XUV pulse will allow extracting the spatio-temporal electron dynamics. ATTOCO offers the capability to measure field-induced material changes in real-time and to gain novel insight into collective electron dynamics. In particular, we aim to learn from ATTOCO in detail, how the collective electron motion is established, how the collective motion is driven by the strong external field and over which pathways and timescale the collective motion decays. ATTOCO provides also a major step in the development of lightwave (nano-)electronics, which may push the frontiers of electronics from multi-gigahertz to petahertz frequencies. If successfully accomplished, this development will herald the potential scalability of electron-based information technologies to lightwave frequencies, surpassing the speed of current computation and communication technology by many orders of magnitude.

1 498 500 €

Start date: 2013-06-01, End date: 2018-05-31

Light is one of today’s most powerful tools for exploriLight is one of today’s most powerful tools for exploring nature at the frontier of the human knowledge. The rapid development of laser technology allow us today to generate ultrashort pulses of coherent structured light: light fields with custom spatial and temporal properties, such as intensity, phase and angular momentum. The later one represents one of the most interesting light properties nowadays, as topological light beams carrying angular momentum interact with matter differently, introducing mechanical motion to micro and nano-structures, and affecting fundamental excitation rules. High-order harmonic generation (HHG) stands as a unique mechanism to provide coherent flashes of light with outstanding properties: its radiation spectrum expands from the vacuum ultraviolet to the soft x-rays; it can be synthesized in pulses as short as several attoseconds (10^-18 seconds): and it can be structured in its angular momentum properties. This proposal represents a timely opportunity to explore the ground-breaking opportunities offered by attosecond structured x-ray sources. It conveys computing light-matter interaction in extreme conditions, which requires an extraordinary effort in the elaboration of new theoretical tools to design, propose and guide future experiments at the frontier of ultrafast science. We shall pioneer the new scenario of angular momenta in structured ultrashort x-rays –the most complex coherent pulses to date–. It is not difficult to envision a new era in ultrafast nanotechnology that makes use of these x-ray sources. In particular we shall pioneer their application to nanoscience and ultrafast magnetism. We aim to establish the grounding principles of attomagnetism, taking advantage of the unique opportunity offered by structured light pulses to induce pure attosecond magnetic fields, which could set the precedents of high-rate magnetic recording through ultrafast magnetization reversal.

1 425 000 €

Start date: 2020-03-01, End date: 2025-02-28

Axions are hypothetical particles whose existence would solve two major problems: the strong P, T problem (a major blemish on the standard model); and the dark matter problem. It is a most important goal to either observe or rule out the existence of a cosmic axion background. It appears that decisive observations may be possible, but only after orchestrating insight from specialities ranging from quantum field theory and astrophysical modeling to ultra-low noise quantum measurement theory. Detailed predictions for the magnitude and structure of the cosmic axion background depend on cosmological and astrophysical modeling, which can be constrained by theoretical insight and numerical simulation. In parallel, we must optimize strategies for extracting accessible signals from that very weakly interacting source. While the existence of axions as fundamental particles remains hypothetical, the equations governing how axions interact with electromagnetic fields also govern (with different parameters) how certain materials interact with electromagnetic fields. Thus those materials embody “emergent” axions. The equations have remarkable properties, which one can test in these materials, and possibly put to practical use. Closely related to axions, mathematically, are anyons. Anyons are particle-like excitations that elude the familiar classification into bosons and fermions. Theoretical and numerical studies indicate that they are common emergent features of highly entangled states of matter in two dimensions. Recent work suggests the existence of states of matter, both natural and engineered, in which anyon dynamics is both important and experimentally accessible. Since the equations for anyons and axions are remarkably similar, and both have common, deep roots in symmetry and topology, it will be fruitful to consider them together.

2 324 391 €

Start date: 2017-09-01, End date: 2022-08-31