Prof. Dr. Daniel Loss Department of Physics Profiles & Affiliations OverviewResearch Publications Projects & Collaborations Projects & Collaborations OverviewResearch Publications Projects & Collaborations Profiles & Affiliations Projects & Collaborations 25 foundShow per page10 10 20 50 NCCR SPIN - Moth A6.4 20% Research Project | 2 Project MembersImported from Grants Tool 4709577 Open quantum many-body systems Research Project | 2 Project MembersImported from Grants Tool 4709943 NCCR SPIN Spin Qubits in Silicon Research Project | 11 Project MembersThe main objective of NCCR SPIN is to develop reliable, fast, compact, scalable spin qubits in silicon and germanium. The vision is to control single spins with electrical means. Fast control of individual spins can be achieved with electrical pulses via a spin-orbit interaction. The spin-orbit interaction is either inherent (hole spin) or synthetic (electron spin in a magnetic field gradient). It also allows neighbouring spins to be coupled together electrically via superconducting resonators or floating gates. The specific aim of the first phase of the project is to develop the silicon spin qubits and spin-spin coupling strategies. Beyond fundamental research on the qubits and their architecture, there are further research efforts in many related areas of quantum computing, such as quantum error correction, quantum information, quantum algorithms and software, qubit control electronics and cryo-MOS, NISQ applications and algorithms. The long term goal is fault-tolerant universal quantum computing with a large number of logical qubits. The NCCR SPIN team consists of researchers from the University of Basel , IBM Research - Zurich , ETH Zurich , and EPF Lausanne . The team members are experts from various disciplines, such as quantum physics, materials science, engineering and computer science. In addition to the collaboration between academia and industry, the NCCR SPIN is characterized by very close links between theory and experiment as well as physics, materials science and engineering. The home institution is the University of Basel . QLSI : Quantum Computing - Large-Scale Integration Research Project | 1 Project MembersWe propose a 4-year project QLSI, Quantum Large Scale Integration in Silicon, which objective is to demonstrate that silicon spin qubits are a compelling platform for scaling to very large numbers of qubits. Our demonstration relies on four ingredients: - Fabrication and operation of 16-qubit quantum processors based on industry-compatible semiconductor technology; - Demonstration of high-fidelity (>99%) single- and two-qubit gates, read-out and initialization; - Demonstration of a quantum computer prototype, with online open-access for the community (up to 8 qubits available online); - Documentation of the detailed requirements to address scalability towards large systems >1000 qubits. To achieve these results, our consortium brings together an unrivalled multidisciplinary team of European groups in academia, RTOs and industry working on silicon-based quantum devices. These groups are committed to playing an active part in developing the industrial ecosystem in silicon-based quantum technologies. QLSI is structured in three enabling toolboxes and one demonstration and scalability activity: - the semiconductor toolbox brings together skills from the semiconductor industry such as fabrication, high throughput test and CAD (computer aided design) with the expertise of the physics community; - the quantum toolbox gathers skills from the physics community on spin and quantum properties of Si based nanostructures and on quantum engineering from theory and experience perspectives; - the control toolbox gathers teams with instrumentation skills ranging from RF signal generation, automation and set up of high throughput characterization at low temperature. The toolboxes will generate stand-alone beyond the state-of-the-art results and will generate inputs to feed the demonstrator and scalability activity, which will integrate devices, hardware and software solutions to create an online open access demonstrator, to perform hybrid computation and to analyze scalability. Majorana Fermions and Parafermions in Topological Insulators Research Project | 4 Project MembersTopological insulators and topological superconductors (TSCs) constitute a new class of quantum materials with a gapped bulk spectrum and gapless surface states. Due to topology, the appearance of these surface states is remarkably robust against external perturbations. In this proposal, we want to discover feasible ways to identify and manipulate Majorana fermions (MFs) and parafermions (PFs) in topological insulator hybrid structures. MFs and PFs are fractional excitations that appear as boundary states of TSCs. They are known to be building blocks for qubits of a topological quantum computer. The system we have identified as the most promising platform for this task is a bilayer quantum spin Hall insulator in proximity to an ordinary s-wave superconductor. In that nanostructure, we expect a complex interplay between helicity, intra- and inter-layer Coulomb interaction, disorder, and superconducting order. The Basel and Würzburg groups, involved in the project, nicely complement each other in terms of theoretical skills (Basel: quantum computing; Würzburg: quantum transport) and the experimental ability (at Würzburg) to actually implement this challenging system in the laboratory. We are therefore confident that we will develop innovative ideas to generate and control MFs and PFs at will within this consortium. TOPSQUAD / TOPOLOGICALLY PROTECTED AND SCALABLE QUANTUM BITS Research Project | 4 Project MembersOur vision is to enable the world of quantum computing through an unprecedented stable and scalable manyqubi system. This platform will allow us to establish important scientific breakthroughs such as the observation of Majorana bound states, which can lead to the new field of non-Abelian many-body physics. A universal quantum computer can be exponentially faster than classical computers for certain scientific and technological applications. This long-awaited innovation can help solve many global challenges of our time related to health, energy and the climate, such as quantum chemistry problems in order to design new medicines, material property prediction for efficient energy storage, big data handling problems, needed for complexity of climate physics. Such a quantum computer has not yet been realized because of qubit fragility and qubit scalability. The output of TOPSQUAD lays the foundation for universal quantum computing with stable and scalable qubits: We will address qubit fragility by creating topological states, which are insensitive to decoherence. We will address qubit scalability by developing waferscale fabrication technology, using CMOS-compatible processes. After TOPSQUAD, existing integrated-circuit technology can then serve to scale up from individual qubits to 100,000s. These two approaches have not been combined within a single system, but our recent results show that we can be the first to address the key challenges: 1. For the first time we will synthesise Ge wires on silicon wafers using scalable CMOS-compatible processes. 2. We will devise an unprecedented silicon system with the required topological properties: Ge wires with a silicon shell. 3. The thin Si shell will suppress metallization, thus avoiding the destruction of topological states by proximityinduced superconductivity, a typically overlooked problem. With this, TOPSQUAD can realize a scalable, CMOS-compatible, topologically protected system. Quantum theory of condensed matter: spin effects in nanostructures and quantum information Research Project | 4 Project MembersThe proposed research covers and interconnects multiple topics from the fields of quantum computing and quantum condensed-matter theory. It contributes to the long term goal of finding realistic architectures that allow the coherent manipulation of solid state systems at the quantum level. Since this goal necessarily involves the study of complex many-body systems, our research goes across many subfields of modern condensed matter and solid state theory and uses a very broad range of sophisticated technical tools.The strategy we pursue encompasses the refinement of the well-established scheme of spin-based quantum computing, as well as efforts to discover novel and realistic platforms that allow the storage and manipulation of quantum information. In view of the desired industrial feasibility and scalability of the results, we focus on the solid state as the basis of our research. Exciting and promising new materials will be examined and their suitability for quantum information processing will be evaluated. Moreover, we will study intriguing issues that are also of interest in fundamental research, ranging from exotic types of topological quantum phases to non- equilibrium dynamics, with focus on spin effects in semiconducting, superconducting, and insulating magnetic nanostructures. Also these fundamental aspects of our proposal are targeted on the ability to gain access to the quantum world. In particular, we plan to work on the following topics:2.A Quantum information and surface code2.B Spin qubits in Si and Ge nanowires2.C Majorana fermion qubits and hybrid spin qubits2.D Stability of topological excitations and qubits2.E Proximity effect in semiconducting nanostructures2.F Topological magnonics2.G Quantum effects of magnetic Skyrmions G. H. Endress Postdoc-Cluster Research Project | 5 Project MembersDas Departement für Physik der Philosophisch-Naturwissenschaftlichen Fakultät der Universität Basel und das Physikalische Institut der Fakultät für Mathematik und Physik der Albert Ludwigs-Universität Freiburg im Breisgau errichten partnerschaftlich ein neues Exzellenzzentrum mit den Forschungsschwerpunkten "Quantum Science and Quantum Computing" unter dem Dach von Eucor - The European Campus . Als tragende Säule dieses Exzellenzzentrums wird ein grenzüberschreitender Postdoc-Cluster zwischen den Universitäten Basel und Freiburg aufgebaut. Primäre Ziele des zukünftigen Postdoc-Clusters sind die hochwertige Ausbildung der Postdocs für den akademischen als auch wirtschaftlichen Arbeitsmarkt und die Positionierung als führende Forschungseinrichtung auf dem Gebiet "Quantum Science and Quantum Computing", im Speziellen durch die verstärkte grenzüberschreitende Zusammenarbeit im Dreiländereck Deutschland-Frankreich-Schweiz. Das Exzellenzzentrum "Quantum Science and Quantum Computing" wird von der Georg H. Endress Stiftung finanziell unterstützt. Spin-NANO Research Project | 2 Project MembersThis network brings together an exceptionally strong team of world-leading experts in nano-science and technology from 6 European countries in order to achieve breakthroughs in understanding and successful utilization of nanoscale solid-state spin systems in emerging quantum technologies. The proposed innovative science in the supra-disciplinary field of physics and applications of spin nano-systems will underpin breakthrough developments in quantum computing, quantum communications and networks, and nano-imaging. An important innovative step consolidating the joint effort of the whole consortium in the studies of spin nano-systems is the focus on crystalline solids where detrimental magnetic interactions of electron spins with lattice nuclei are negligible and wellcontrolled. We will develop electrically-controlled spin-quantum-bits (qubits) in Si-Ge quantum dots and nanowires; will optically manipulate spin impurities in diamond in applications for quantum computing and networks and in nano-magnetometry; will achieve new understanding of quantum phenomena due to the spinvalley coupling in atomically thin 2D semiconductors, an emerging class of materials with a promise for quantum technologies using a new quantum degree of freedom, the valley index. Such wide material base emphasizes the truly multidisciplinary character of this collaboration opening opportunities for crossing the boundaries between several areas of solid-state physics and technology. The consortium of 14 academic and 7 industrial groups will deliver top international level multidisciplinary training to 15 early stage researchers, offering them an extended program of multinational exchanges and secondments. Network-wide training course in transferable skills will be specially developed and delivered by the Think Ahead (Sheffield), an award winning programme supporting Early Career Researchers (award by the Times Higher Education, 2014). The new network builds on the success of FP7 ITN S3NANO (also coordinated by A Tartakovskii), which has delivered excellent training to 16 researchers as well as state-of-the-art nano-science and technology. The current proposal is designed to advance this multidisciplinary research field significantly beyond the state-of-the-art, and train a new cohort of researchers capable of developing spin-based solid-state quantum technologies towards real-life applications in the next 5 to 10 years. Clean Zigzag and Armchair Graphene Nanoribbons Research Project | 2 Project MembersIn the envisioned experiments, we will develop new fabrication techniques aimed at creating ultra-clean graphene nanoribbons with high-quality zigzag or armchair edge termination. We will perform low-noise electronic transport measurement at low temperatures in magnetic fields in order to investigate novel quantum states of matter such as graphene ballistic 1D modes, edge antiferromagnetism, helical states and Majorana fermions. 123 123 OverviewResearch Publications Projects & Collaborations
Projects & Collaborations 25 foundShow per page10 10 20 50 NCCR SPIN - Moth A6.4 20% Research Project | 2 Project MembersImported from Grants Tool 4709577 Open quantum many-body systems Research Project | 2 Project MembersImported from Grants Tool 4709943 NCCR SPIN Spin Qubits in Silicon Research Project | 11 Project MembersThe main objective of NCCR SPIN is to develop reliable, fast, compact, scalable spin qubits in silicon and germanium. The vision is to control single spins with electrical means. Fast control of individual spins can be achieved with electrical pulses via a spin-orbit interaction. The spin-orbit interaction is either inherent (hole spin) or synthetic (electron spin in a magnetic field gradient). It also allows neighbouring spins to be coupled together electrically via superconducting resonators or floating gates. The specific aim of the first phase of the project is to develop the silicon spin qubits and spin-spin coupling strategies. Beyond fundamental research on the qubits and their architecture, there are further research efforts in many related areas of quantum computing, such as quantum error correction, quantum information, quantum algorithms and software, qubit control electronics and cryo-MOS, NISQ applications and algorithms. The long term goal is fault-tolerant universal quantum computing with a large number of logical qubits. The NCCR SPIN team consists of researchers from the University of Basel , IBM Research - Zurich , ETH Zurich , and EPF Lausanne . The team members are experts from various disciplines, such as quantum physics, materials science, engineering and computer science. In addition to the collaboration between academia and industry, the NCCR SPIN is characterized by very close links between theory and experiment as well as physics, materials science and engineering. The home institution is the University of Basel . QLSI : Quantum Computing - Large-Scale Integration Research Project | 1 Project MembersWe propose a 4-year project QLSI, Quantum Large Scale Integration in Silicon, which objective is to demonstrate that silicon spin qubits are a compelling platform for scaling to very large numbers of qubits. Our demonstration relies on four ingredients: - Fabrication and operation of 16-qubit quantum processors based on industry-compatible semiconductor technology; - Demonstration of high-fidelity (>99%) single- and two-qubit gates, read-out and initialization; - Demonstration of a quantum computer prototype, with online open-access for the community (up to 8 qubits available online); - Documentation of the detailed requirements to address scalability towards large systems >1000 qubits. To achieve these results, our consortium brings together an unrivalled multidisciplinary team of European groups in academia, RTOs and industry working on silicon-based quantum devices. These groups are committed to playing an active part in developing the industrial ecosystem in silicon-based quantum technologies. QLSI is structured in three enabling toolboxes and one demonstration and scalability activity: - the semiconductor toolbox brings together skills from the semiconductor industry such as fabrication, high throughput test and CAD (computer aided design) with the expertise of the physics community; - the quantum toolbox gathers skills from the physics community on spin and quantum properties of Si based nanostructures and on quantum engineering from theory and experience perspectives; - the control toolbox gathers teams with instrumentation skills ranging from RF signal generation, automation and set up of high throughput characterization at low temperature. The toolboxes will generate stand-alone beyond the state-of-the-art results and will generate inputs to feed the demonstrator and scalability activity, which will integrate devices, hardware and software solutions to create an online open access demonstrator, to perform hybrid computation and to analyze scalability. Majorana Fermions and Parafermions in Topological Insulators Research Project | 4 Project MembersTopological insulators and topological superconductors (TSCs) constitute a new class of quantum materials with a gapped bulk spectrum and gapless surface states. Due to topology, the appearance of these surface states is remarkably robust against external perturbations. In this proposal, we want to discover feasible ways to identify and manipulate Majorana fermions (MFs) and parafermions (PFs) in topological insulator hybrid structures. MFs and PFs are fractional excitations that appear as boundary states of TSCs. They are known to be building blocks for qubits of a topological quantum computer. The system we have identified as the most promising platform for this task is a bilayer quantum spin Hall insulator in proximity to an ordinary s-wave superconductor. In that nanostructure, we expect a complex interplay between helicity, intra- and inter-layer Coulomb interaction, disorder, and superconducting order. The Basel and Würzburg groups, involved in the project, nicely complement each other in terms of theoretical skills (Basel: quantum computing; Würzburg: quantum transport) and the experimental ability (at Würzburg) to actually implement this challenging system in the laboratory. We are therefore confident that we will develop innovative ideas to generate and control MFs and PFs at will within this consortium. TOPSQUAD / TOPOLOGICALLY PROTECTED AND SCALABLE QUANTUM BITS Research Project | 4 Project MembersOur vision is to enable the world of quantum computing through an unprecedented stable and scalable manyqubi system. This platform will allow us to establish important scientific breakthroughs such as the observation of Majorana bound states, which can lead to the new field of non-Abelian many-body physics. A universal quantum computer can be exponentially faster than classical computers for certain scientific and technological applications. This long-awaited innovation can help solve many global challenges of our time related to health, energy and the climate, such as quantum chemistry problems in order to design new medicines, material property prediction for efficient energy storage, big data handling problems, needed for complexity of climate physics. Such a quantum computer has not yet been realized because of qubit fragility and qubit scalability. The output of TOPSQUAD lays the foundation for universal quantum computing with stable and scalable qubits: We will address qubit fragility by creating topological states, which are insensitive to decoherence. We will address qubit scalability by developing waferscale fabrication technology, using CMOS-compatible processes. After TOPSQUAD, existing integrated-circuit technology can then serve to scale up from individual qubits to 100,000s. These two approaches have not been combined within a single system, but our recent results show that we can be the first to address the key challenges: 1. For the first time we will synthesise Ge wires on silicon wafers using scalable CMOS-compatible processes. 2. We will devise an unprecedented silicon system with the required topological properties: Ge wires with a silicon shell. 3. The thin Si shell will suppress metallization, thus avoiding the destruction of topological states by proximityinduced superconductivity, a typically overlooked problem. With this, TOPSQUAD can realize a scalable, CMOS-compatible, topologically protected system. Quantum theory of condensed matter: spin effects in nanostructures and quantum information Research Project | 4 Project MembersThe proposed research covers and interconnects multiple topics from the fields of quantum computing and quantum condensed-matter theory. It contributes to the long term goal of finding realistic architectures that allow the coherent manipulation of solid state systems at the quantum level. Since this goal necessarily involves the study of complex many-body systems, our research goes across many subfields of modern condensed matter and solid state theory and uses a very broad range of sophisticated technical tools.The strategy we pursue encompasses the refinement of the well-established scheme of spin-based quantum computing, as well as efforts to discover novel and realistic platforms that allow the storage and manipulation of quantum information. In view of the desired industrial feasibility and scalability of the results, we focus on the solid state as the basis of our research. Exciting and promising new materials will be examined and their suitability for quantum information processing will be evaluated. Moreover, we will study intriguing issues that are also of interest in fundamental research, ranging from exotic types of topological quantum phases to non- equilibrium dynamics, with focus on spin effects in semiconducting, superconducting, and insulating magnetic nanostructures. Also these fundamental aspects of our proposal are targeted on the ability to gain access to the quantum world. In particular, we plan to work on the following topics:2.A Quantum information and surface code2.B Spin qubits in Si and Ge nanowires2.C Majorana fermion qubits and hybrid spin qubits2.D Stability of topological excitations and qubits2.E Proximity effect in semiconducting nanostructures2.F Topological magnonics2.G Quantum effects of magnetic Skyrmions G. H. Endress Postdoc-Cluster Research Project | 5 Project MembersDas Departement für Physik der Philosophisch-Naturwissenschaftlichen Fakultät der Universität Basel und das Physikalische Institut der Fakultät für Mathematik und Physik der Albert Ludwigs-Universität Freiburg im Breisgau errichten partnerschaftlich ein neues Exzellenzzentrum mit den Forschungsschwerpunkten "Quantum Science and Quantum Computing" unter dem Dach von Eucor - The European Campus . Als tragende Säule dieses Exzellenzzentrums wird ein grenzüberschreitender Postdoc-Cluster zwischen den Universitäten Basel und Freiburg aufgebaut. Primäre Ziele des zukünftigen Postdoc-Clusters sind die hochwertige Ausbildung der Postdocs für den akademischen als auch wirtschaftlichen Arbeitsmarkt und die Positionierung als führende Forschungseinrichtung auf dem Gebiet "Quantum Science and Quantum Computing", im Speziellen durch die verstärkte grenzüberschreitende Zusammenarbeit im Dreiländereck Deutschland-Frankreich-Schweiz. Das Exzellenzzentrum "Quantum Science and Quantum Computing" wird von der Georg H. Endress Stiftung finanziell unterstützt. Spin-NANO Research Project | 2 Project MembersThis network brings together an exceptionally strong team of world-leading experts in nano-science and technology from 6 European countries in order to achieve breakthroughs in understanding and successful utilization of nanoscale solid-state spin systems in emerging quantum technologies. The proposed innovative science in the supra-disciplinary field of physics and applications of spin nano-systems will underpin breakthrough developments in quantum computing, quantum communications and networks, and nano-imaging. An important innovative step consolidating the joint effort of the whole consortium in the studies of spin nano-systems is the focus on crystalline solids where detrimental magnetic interactions of electron spins with lattice nuclei are negligible and wellcontrolled. We will develop electrically-controlled spin-quantum-bits (qubits) in Si-Ge quantum dots and nanowires; will optically manipulate spin impurities in diamond in applications for quantum computing and networks and in nano-magnetometry; will achieve new understanding of quantum phenomena due to the spinvalley coupling in atomically thin 2D semiconductors, an emerging class of materials with a promise for quantum technologies using a new quantum degree of freedom, the valley index. Such wide material base emphasizes the truly multidisciplinary character of this collaboration opening opportunities for crossing the boundaries between several areas of solid-state physics and technology. The consortium of 14 academic and 7 industrial groups will deliver top international level multidisciplinary training to 15 early stage researchers, offering them an extended program of multinational exchanges and secondments. Network-wide training course in transferable skills will be specially developed and delivered by the Think Ahead (Sheffield), an award winning programme supporting Early Career Researchers (award by the Times Higher Education, 2014). The new network builds on the success of FP7 ITN S3NANO (also coordinated by A Tartakovskii), which has delivered excellent training to 16 researchers as well as state-of-the-art nano-science and technology. The current proposal is designed to advance this multidisciplinary research field significantly beyond the state-of-the-art, and train a new cohort of researchers capable of developing spin-based solid-state quantum technologies towards real-life applications in the next 5 to 10 years. Clean Zigzag and Armchair Graphene Nanoribbons Research Project | 2 Project MembersIn the envisioned experiments, we will develop new fabrication techniques aimed at creating ultra-clean graphene nanoribbons with high-quality zigzag or armchair edge termination. We will perform low-noise electronic transport measurement at low temperatures in magnetic fields in order to investigate novel quantum states of matter such as graphene ballistic 1D modes, edge antiferromagnetism, helical states and Majorana fermions. 123 123
NCCR SPIN Spin Qubits in Silicon Research Project | 11 Project MembersThe main objective of NCCR SPIN is to develop reliable, fast, compact, scalable spin qubits in silicon and germanium. The vision is to control single spins with electrical means. Fast control of individual spins can be achieved with electrical pulses via a spin-orbit interaction. The spin-orbit interaction is either inherent (hole spin) or synthetic (electron spin in a magnetic field gradient). It also allows neighbouring spins to be coupled together electrically via superconducting resonators or floating gates. The specific aim of the first phase of the project is to develop the silicon spin qubits and spin-spin coupling strategies. Beyond fundamental research on the qubits and their architecture, there are further research efforts in many related areas of quantum computing, such as quantum error correction, quantum information, quantum algorithms and software, qubit control electronics and cryo-MOS, NISQ applications and algorithms. The long term goal is fault-tolerant universal quantum computing with a large number of logical qubits. The NCCR SPIN team consists of researchers from the University of Basel , IBM Research - Zurich , ETH Zurich , and EPF Lausanne . The team members are experts from various disciplines, such as quantum physics, materials science, engineering and computer science. In addition to the collaboration between academia and industry, the NCCR SPIN is characterized by very close links between theory and experiment as well as physics, materials science and engineering. The home institution is the University of Basel .
QLSI : Quantum Computing - Large-Scale Integration Research Project | 1 Project MembersWe propose a 4-year project QLSI, Quantum Large Scale Integration in Silicon, which objective is to demonstrate that silicon spin qubits are a compelling platform for scaling to very large numbers of qubits. Our demonstration relies on four ingredients: - Fabrication and operation of 16-qubit quantum processors based on industry-compatible semiconductor technology; - Demonstration of high-fidelity (>99%) single- and two-qubit gates, read-out and initialization; - Demonstration of a quantum computer prototype, with online open-access for the community (up to 8 qubits available online); - Documentation of the detailed requirements to address scalability towards large systems >1000 qubits. To achieve these results, our consortium brings together an unrivalled multidisciplinary team of European groups in academia, RTOs and industry working on silicon-based quantum devices. These groups are committed to playing an active part in developing the industrial ecosystem in silicon-based quantum technologies. QLSI is structured in three enabling toolboxes and one demonstration and scalability activity: - the semiconductor toolbox brings together skills from the semiconductor industry such as fabrication, high throughput test and CAD (computer aided design) with the expertise of the physics community; - the quantum toolbox gathers skills from the physics community on spin and quantum properties of Si based nanostructures and on quantum engineering from theory and experience perspectives; - the control toolbox gathers teams with instrumentation skills ranging from RF signal generation, automation and set up of high throughput characterization at low temperature. The toolboxes will generate stand-alone beyond the state-of-the-art results and will generate inputs to feed the demonstrator and scalability activity, which will integrate devices, hardware and software solutions to create an online open access demonstrator, to perform hybrid computation and to analyze scalability.
Majorana Fermions and Parafermions in Topological Insulators Research Project | 4 Project MembersTopological insulators and topological superconductors (TSCs) constitute a new class of quantum materials with a gapped bulk spectrum and gapless surface states. Due to topology, the appearance of these surface states is remarkably robust against external perturbations. In this proposal, we want to discover feasible ways to identify and manipulate Majorana fermions (MFs) and parafermions (PFs) in topological insulator hybrid structures. MFs and PFs are fractional excitations that appear as boundary states of TSCs. They are known to be building blocks for qubits of a topological quantum computer. The system we have identified as the most promising platform for this task is a bilayer quantum spin Hall insulator in proximity to an ordinary s-wave superconductor. In that nanostructure, we expect a complex interplay between helicity, intra- and inter-layer Coulomb interaction, disorder, and superconducting order. The Basel and Würzburg groups, involved in the project, nicely complement each other in terms of theoretical skills (Basel: quantum computing; Würzburg: quantum transport) and the experimental ability (at Würzburg) to actually implement this challenging system in the laboratory. We are therefore confident that we will develop innovative ideas to generate and control MFs and PFs at will within this consortium.
TOPSQUAD / TOPOLOGICALLY PROTECTED AND SCALABLE QUANTUM BITS Research Project | 4 Project MembersOur vision is to enable the world of quantum computing through an unprecedented stable and scalable manyqubi system. This platform will allow us to establish important scientific breakthroughs such as the observation of Majorana bound states, which can lead to the new field of non-Abelian many-body physics. A universal quantum computer can be exponentially faster than classical computers for certain scientific and technological applications. This long-awaited innovation can help solve many global challenges of our time related to health, energy and the climate, such as quantum chemistry problems in order to design new medicines, material property prediction for efficient energy storage, big data handling problems, needed for complexity of climate physics. Such a quantum computer has not yet been realized because of qubit fragility and qubit scalability. The output of TOPSQUAD lays the foundation for universal quantum computing with stable and scalable qubits: We will address qubit fragility by creating topological states, which are insensitive to decoherence. We will address qubit scalability by developing waferscale fabrication technology, using CMOS-compatible processes. After TOPSQUAD, existing integrated-circuit technology can then serve to scale up from individual qubits to 100,000s. These two approaches have not been combined within a single system, but our recent results show that we can be the first to address the key challenges: 1. For the first time we will synthesise Ge wires on silicon wafers using scalable CMOS-compatible processes. 2. We will devise an unprecedented silicon system with the required topological properties: Ge wires with a silicon shell. 3. The thin Si shell will suppress metallization, thus avoiding the destruction of topological states by proximityinduced superconductivity, a typically overlooked problem. With this, TOPSQUAD can realize a scalable, CMOS-compatible, topologically protected system.
Quantum theory of condensed matter: spin effects in nanostructures and quantum information Research Project | 4 Project MembersThe proposed research covers and interconnects multiple topics from the fields of quantum computing and quantum condensed-matter theory. It contributes to the long term goal of finding realistic architectures that allow the coherent manipulation of solid state systems at the quantum level. Since this goal necessarily involves the study of complex many-body systems, our research goes across many subfields of modern condensed matter and solid state theory and uses a very broad range of sophisticated technical tools.The strategy we pursue encompasses the refinement of the well-established scheme of spin-based quantum computing, as well as efforts to discover novel and realistic platforms that allow the storage and manipulation of quantum information. In view of the desired industrial feasibility and scalability of the results, we focus on the solid state as the basis of our research. Exciting and promising new materials will be examined and their suitability for quantum information processing will be evaluated. Moreover, we will study intriguing issues that are also of interest in fundamental research, ranging from exotic types of topological quantum phases to non- equilibrium dynamics, with focus on spin effects in semiconducting, superconducting, and insulating magnetic nanostructures. Also these fundamental aspects of our proposal are targeted on the ability to gain access to the quantum world. In particular, we plan to work on the following topics:2.A Quantum information and surface code2.B Spin qubits in Si and Ge nanowires2.C Majorana fermion qubits and hybrid spin qubits2.D Stability of topological excitations and qubits2.E Proximity effect in semiconducting nanostructures2.F Topological magnonics2.G Quantum effects of magnetic Skyrmions
G. H. Endress Postdoc-Cluster Research Project | 5 Project MembersDas Departement für Physik der Philosophisch-Naturwissenschaftlichen Fakultät der Universität Basel und das Physikalische Institut der Fakultät für Mathematik und Physik der Albert Ludwigs-Universität Freiburg im Breisgau errichten partnerschaftlich ein neues Exzellenzzentrum mit den Forschungsschwerpunkten "Quantum Science and Quantum Computing" unter dem Dach von Eucor - The European Campus . Als tragende Säule dieses Exzellenzzentrums wird ein grenzüberschreitender Postdoc-Cluster zwischen den Universitäten Basel und Freiburg aufgebaut. Primäre Ziele des zukünftigen Postdoc-Clusters sind die hochwertige Ausbildung der Postdocs für den akademischen als auch wirtschaftlichen Arbeitsmarkt und die Positionierung als führende Forschungseinrichtung auf dem Gebiet "Quantum Science and Quantum Computing", im Speziellen durch die verstärkte grenzüberschreitende Zusammenarbeit im Dreiländereck Deutschland-Frankreich-Schweiz. Das Exzellenzzentrum "Quantum Science and Quantum Computing" wird von der Georg H. Endress Stiftung finanziell unterstützt.
Spin-NANO Research Project | 2 Project MembersThis network brings together an exceptionally strong team of world-leading experts in nano-science and technology from 6 European countries in order to achieve breakthroughs in understanding and successful utilization of nanoscale solid-state spin systems in emerging quantum technologies. The proposed innovative science in the supra-disciplinary field of physics and applications of spin nano-systems will underpin breakthrough developments in quantum computing, quantum communications and networks, and nano-imaging. An important innovative step consolidating the joint effort of the whole consortium in the studies of spin nano-systems is the focus on crystalline solids where detrimental magnetic interactions of electron spins with lattice nuclei are negligible and wellcontrolled. We will develop electrically-controlled spin-quantum-bits (qubits) in Si-Ge quantum dots and nanowires; will optically manipulate spin impurities in diamond in applications for quantum computing and networks and in nano-magnetometry; will achieve new understanding of quantum phenomena due to the spinvalley coupling in atomically thin 2D semiconductors, an emerging class of materials with a promise for quantum technologies using a new quantum degree of freedom, the valley index. Such wide material base emphasizes the truly multidisciplinary character of this collaboration opening opportunities for crossing the boundaries between several areas of solid-state physics and technology. The consortium of 14 academic and 7 industrial groups will deliver top international level multidisciplinary training to 15 early stage researchers, offering them an extended program of multinational exchanges and secondments. Network-wide training course in transferable skills will be specially developed and delivered by the Think Ahead (Sheffield), an award winning programme supporting Early Career Researchers (award by the Times Higher Education, 2014). The new network builds on the success of FP7 ITN S3NANO (also coordinated by A Tartakovskii), which has delivered excellent training to 16 researchers as well as state-of-the-art nano-science and technology. The current proposal is designed to advance this multidisciplinary research field significantly beyond the state-of-the-art, and train a new cohort of researchers capable of developing spin-based solid-state quantum technologies towards real-life applications in the next 5 to 10 years.
Clean Zigzag and Armchair Graphene Nanoribbons Research Project | 2 Project MembersIn the envisioned experiments, we will develop new fabrication techniques aimed at creating ultra-clean graphene nanoribbons with high-quality zigzag or armchair edge termination. We will perform low-noise electronic transport measurement at low temperatures in magnetic fields in order to investigate novel quantum states of matter such as graphene ballistic 1D modes, edge antiferromagnetism, helical states and Majorana fermions.
