Title Promoter Affiliations Abstract "New Geometry of Quantum Dynamics (QUANTUM DYNAMICS)" "Kenny De Commer" "Topological Algebra, Functional Analysis and Category Theory, Mathematics" "The Project aims to make significant advances to the field of noncommutative geometry by developing new methods through substantial interaction within sub-fields of noncommutative geometry and two other areas of pure mathematics. The main focus will be to determine the topological non-triviality of new types of quantum fibrations. Also, we aim to construct quantum metric geometries of crossed products and graph algebras relating the Lipschitz-norm and Dirac-operator approaches. The Project will combine various areas, which although interacting on the fundamental level, have had their concrete and usable connections mostly unexplored. The success of the Project depends on connecting centres of excellence in relevant topics for the exchange of ideas and and production of high-quality collaborative results. The network has been carefully chosen to include the world's leading experts as well as promising early career researchers. Not only does this guarantee the participants access to an enormous knowledge base, it will also ensure that new and innovative lines of research will continue to be developed long after the Project has finished. In particular, the collaborative nature of the project will be of great benefit to the early career researchers involved. In pure mathematics, fields often become so specialised that only a small number of people around the world might be actively researching a particular topic. This can make career progression very difficult. The interdisciplinary nature of the Project will expose the participants to a host of new mathematics and new collaborations. Consequently, this diversification will result in significantly more career opportunities than would otherwise be available." "Questioning the quantum: On Thomas Kuhn and 'Sources for the History of Quantum Physics'." "Bert Leuridan" "Centre for Philosophical Psychology" "Thomas Kuhn is primarily known for his book 'The Structure of Scientific Revolutions' (1962). There, he offered a novel philosophical view on the history of science: science is not continuously progressive, but rather goes through radical paradigm-changes. Less known is that Kuhn in 1962 also started a project to map the history of quantum mechanics. This project, titled 'Sources for History of Quantum Physics', aimed to collect as many source materials as possible, and to interview physicists who had participated in these changes. It was very innovative, because interview methods had never been used before in history of science. Because of the size of its output, the project still acts as a source for many historians and philosophers today. My aim is to carry out a historical-philosophical study of the Sources-project. On the one hand, I will study its place in Kuhn's thinking: how does it compare to his views on paradigms, and did it influence his later work? On the other hand, I will investigate its influence on later historical-philosophical debates, in particular concerning what quantum mechanics can teach us about the nature of physical reality. Finally, I will also reflect on whether philosophical views about science in general shaped the project, and hence, possibly, also these later debates." "Making a quantum computer talk chemistry: conceptual open quantum systems as insightful tools for quantum computing approaches to quantum chemistry" "Patrick Bultinck" "Department of Chemistry" "Quantum computers have the potential to revolutionize quantum chemistry because they can, in principle, compute accurate electronic structure models very efficiently. At the moment, however, we are technologically limited to so-called ‘noisy intermediate-scaling quantum' (NISQ) devices, which suffer from calculation errors (noise) because they are very sensitive to their environment. Despite these noise issues, accurate molecular energies can be obtained on NISQ devices, but unfortunately only when the underlying wave function is variationally forced to overcorrect for the computational errors made by the quantum computer. In this project, we will show that relying on such error corrections negatively impacts the quality of the wave function and causes unreliable performance for general chemical applications. By analyzing how quantum computing wave functions describe the atoms in the molecule, we will uncover their chemical content and will determine if they erroneously predict molecules to dissociate into fractionally charged atoms. Moreover, we will demonstrate that atoms as conceptual open quantum systems offer the ideal tools to solve quantum computational errors in an innovative way without compromising on quality. In this way, we intend to create the first 'killer quantum computing app' that allows researchers to fully apply the power of quantum computing to their research without sacrificing the chemical concepts they hold dear." "Making a quantum computer talk chemistry: conceptual open quantum systems as insightful tools for quantum computing approaches to quantum chemistry" "Patrick Bultinck" "Department of Chemistry" "Quantum computers have the potential to revolutionize quantum chemistry because they can, in principle, compute accurate electronic structure models very efficiently. At the moment, however, we are technologically limited to so-called ‘noisy intermediate-scaling quantum' (NISQ) devices, which suffer from calculation errors (noise) because they are very sensitive to their environment. Despite these noise issues, accurate molecular energies can be obtained on NISQ devices, but unfortunately only when the underlying wave function is variationally forced to overcorrect for the computational errors made by the quantum computer. In this project, we will show that relying on such error corrections negatively impacts the quality of the wave function and causes unreliable performance for general chemical applications. By analyzing how quantum computing wave functions describe the atoms in the molecule, we will uncover their chemical content and will determine if they erroneously predict molecules to dissociate into fractionally charged atoms. Moreover, we will demonstrate that atoms as conceptual open quantum systems offer the ideal tools to solve quantum computational errors in an innovative way without compromising on quality. In this way, we intend to create the first 'killer quantum computing app' that allows researchers to fully apply the power of quantum computing to their research without sacrificing the chemical concepts they hold dear." "Quantum chaos and quantum complexity in quantum resonant systems." "Ben Craps" "Physics, WE Academic Unit" "I will study quantum chaos and quantum complexity in the novel context of quantum resonant systems. Quantum resonant systems arise upon quantizing classical resonant systems. The latter provide controlled approximations to the dynamics of interesting classes of weakly nonlinear systems, including weakly interacting Bose-Einstein condensates in harmonic traps and weakly interacting fields in antide Sitter (AdS) spacetime. Quantum resonant systems are attractive for several reasons. First, their Hamiltonian exhibits a block-diagonal structure, which makes them tractable despite having an infinite-dimensional Hilbert space. Second, the corresponding classical resonant systems provide natural semi-classical limits. Third, classical resonant systems display a rich variety of behaviour (e.g. chaotic vs integrable, turbulent or not). Finally, quantum resonant systems are directly relevant to the study of physical systems such as bosons in harmonic traps and quantum fields in AdS spacetime. Quantum chaos will be studied by quantifying how the energy level spacing statistics and out-of-time-order correlators interpolate between integrable and chaotic systems. At the same time, it will be tested to what extent these systems satisfy the Eigenstate Thermalization Hypothesis. Quantum complexity will be studied through the calculation of an upper bound on complexity for different models. I will also quantify how this bound changes when interpolating between integrable and chaotic systems" "Quantum symmetric spaces, operator algebras and quantum cluster algebras" "Kenny De Commer" "Mathematics, Topological Algebra, Functional Analysis and Category Theory" "The mathematician's notion of space has continuously evolved throughout the history of the subject. For the ancient Greeks, space was seen as a background continuum in which certain structures such as lines, triangles, circles and planes can be housed and studied. Their synthetic approach was subsequently supplemented by the Cartesian method in which algebraic methods were used to study for example curves in a plane. Gradually, it was realized that there is such a thing as an abstract space, which can have many different forms and inherent structure. A highlight in this development is the work of B. Riemann, which proved to provide the appropriate mathematical framework in which to develop the physical theory of general relativity. At the same time, the theory of quantum mechanics has shown the need for a notion of quantum space, to be understood by the methods of abstract non-commutative algebra. The goal of this project is to study in depth a particular class of such quantum spaces. In the realm of Riemannian spaces, there is a class with a very high degree of symmetry, known as symmetric spaces. These were studied and classified by E. Cartan at the beginning of the 20th century. Only recently, particularly through the work of G. Letzter, has it become apparent that one has a corresponding notion of quantum symmetric space. We will investigate these quantum symmetric spaces both with analytic methods (operator algebras) and algebraic methods (quantum cluster algebras)." "Quantum complexity, quantum entanglement and the emergence of spacetime" "Ben Craps" "Physics, WE Academic Unit" "Research over the last decade has established that appropriately structured non-local quantum entanglement may underpin the emergence of spacetime from the underlying degrees of freedom, and the recovery of information from black holes. To realize this picture in the model that describes M-theory, the master theory in 11 dimensions from which all string theories descend, we must learn how to describe and compute entanglement between the degrees of freedom in systems of interacting matrices. We propose to develop this formalism and to apply it to the matrix model of M-theory. Meanwhile, another chain of reasoning has suggested that, in addition to entanglement, the complexity of time evolution, treated as a quantum computation, is also geometrized via holographic dualities with gravitating theories. This connection has led to precise conjectures differentiating integrable and chaotic systems. We propose to test these conjectures by developing and applying a recent quantitative definition of complexity of time evolution in physical theories. We will also develop the relation between complexity and non-local entanglement patterns in quantum states of the kind required for black hole information recovery" "Quantum information for quantum fiel" "Henri Verschelde" "Department of Physics and astronomy" "Recently, borrowing techniques and concepts from quantum information theory, two powerfull methods (PEPS and MERA) appeared, that allow a new quantitative and qualitative understanding of discrete quantum systems. The overall goal of our research project is to contribute to the exploration of these methods in the context of quantum field theories. This could provide a new framework for the study of the strongly coupled regime in dynamical situations, relevant for our understanding of heavy-ion-collisions, for instance." "Hardware efficient microarchitecture and quantum error correction codes for large scale quantum processors" "Kristiaan De Greve" "Assiocated Division ESAT-INSYS (INSYS), Integrated Systems, Micro- and Nano Systems (MNS)" "With the recent demonstration of quantum supremacy, quantum computing is entering the era of Noisy Intermediate Scale Quantum computing (NISQ), where dozens to several hundreds of artificial quantum objects interact in such a way as to perform computationally intractable yet trivial tasks such as simulating their own behavior [1]. Yet, even the most optimistic estimates assume that many millions of qubits will be required for properly executing meaningful tasks such as quantum chemistry. At the heart of this discrepancy is the enormous overhead required to mitigate the effect of errors and to realize fault-tolerant quantum computation [2]. At imec, we are therefore developing methods and technology to improve the prospect of scaling up quantum processors to truly useful levels, by leveraging the advanced process control and extreme accuracy present in advanced microfabrication methods such as those present in semiconductor foundries. By homogenizing the qubits (reduced variability) and removing physical sources of noise and decoherence (surface, interface, defect control), we aim to increase the fidelity of the qubits and facilitate more robust control. Our efforts thus far have focused on superconducting [3] and spin qubits [4], both of which were shown to benefit from the advanced fabrication methods available. The aim of this thesis is to help design microarchitectures and optimized error correction schemes, tailored to the hardware platforms under development. By exploiting asymmetries in the noise behavior of particular qubit designs, recent studies showed that error correction overheads could be significantly reduced [5] compared to more generic codes that assume ‘worst case’ behavior. Potential variants will be investigated that are compatible with the hardware under development, and that try to exploit specifics thereof. One particular example involves the possibility of designing error correction schemes tailored to time-division multiplexed control of qubits [6]: in view of the massive I/O problem, many groups worldwide (including imec) are looking at multiplexed qubit control as a potential scaling mitigation mechanism. Can codes and microarchitectures be designed that exploit such multiplexed behavior? [1] F. Arute et al., Quantum supremacy using a programmable superconducting processor, Nature 574, 505 (2019) [2] S. Devitt et al, Quantum error correction for beginners, Rep. Prog. Phys. 76, 076001 (2013) [3] M. Devoret Superconducting circuits for quantum information: an outlook, Science 339, 1169 (2013) [4] L. Vandersypen et al., Quantum computing with semiconducting spins, Physics today 72, 38 (2019) [5] S. Puri et al., Bias preserving gates with stabilized cat qubits, Science Adv. 6, 34 (2020) [6] R. Acharya et al., Scalable 1.4 µW cryo-CMOS SP4T multiplexer operating at 10 mK for high-fidelity superconducting qubit measurements, VLSI symposium 2022 (invited)" "Investigating signatures of quantum gravity via classical and quantum corrections in black holes" "Nikolay Bobev" "Theoretical Physics" "One outstanding challenge in fundamental physics pertains to finding a consistent theory of quantum gravity - the intersection of gravitational physics and quantum physics. Black holes are interesting models to understand the quantum structure of gravity. As technology has advanced and there have been more experimental probes for gravity, it is then time to provide additional theoretical predictions that may ultimately be observed. Of particular relevance is the investigation of certain signatures that provide access to the quantum gravity under consideration. In this proposal, the motivation of the types of signatures, leading corrections, I will explore is twofold. First, the classical corrections determine the necessary modifications of Einstein’s theory of General Relativity and second, the quantum corrections allow a strict criterion for which quantum theories of gravity are allowed."