Prof. Dr. Jelena Klinovaja Department of Physics Profiles & Affiliations OverviewResearch Publications Projects & Collaborations Projects & Collaborations OverviewResearch Publications Projects & Collaborations Profiles & Affiliations Projects & Collaborations 7 foundShow per page10 10 20 50 Open quantum many-body systems Research Project | 2 Project MembersImported from Grants Tool 4709943 CavitySuperTop: Cavity-induced superconductivity and topological states of matter Research Project | 1 Project MembersNo Description available 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 . 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. ETOPEX/Engineering Topological Phases and Excitations in Nanostructures Research Project | 1 Project MembersThe main goal of this theory project is to propose engineered topological phases emerging only in strongly interacting systems and to identify the most feasible systems for experimental implementation. First, we will focus on setups hosting topological states localized at domain walls in one-dimensional channels such as parafermions, which are a new class of non-Abelian anyons and most promising candidates for topological quantum computing schemes. Second, in the framework of weakly coupled wires and planes, we will develop schemes for novel fractional topological phases in two- and three-dimensional interacting systems. To achieve these two goals, my team will identify necessary ingredients such as strong electron-electron interactions, helical magnetic order, or crossed Andreev proximity-induced superconductivity and address each of them separately. Later, we combine them to lead us to the desired topological phases and states. On our way to the main goal, as test cases, we will also study non-interacting analogies of the proposed effects such as Majorana fermions and integer topological insulators and pay close attention to the rapid experimental progress to come up with the most feasible proposals. We will study transport properties, scanning tunneling and atomic force microscopy. Especially for systems driven out of equilibrium, we will develop a Floquet-Luttinger liquid technique. We will explore the stability of engineered topological phases, error rates of topological qubits based on them, and computation schemes allowing for a set of universal qubit gates. We will strive to find a reasonable balance between topological stability and experimental feasibility of setups. Our main theoretical tools are Luttinger liquid techniques (bosonization and renormalization group), Green functions, Floquet formalism, and numerical simulations in non-interacting test models. Topological quantum bound states: Shiba, Majorana, and parafermions bound states Research Project | 7 Project MembersThe present proposal focuses on topological quantum effects in condensed matter physics. Topological quantum effects is a relatively young field, however, it has the potential to become an essential part of future technology. The field began with purely theoretical proposals on topologically protected quantum computation schemes, however, in a very short time, first seminal experiments demonstrating signatures of topological insulators and Majorana bound states were carried out. These pioneering experiments give us hope that indeed topological effects and their unique stability to local perturbations exist in Nature even if it is not so straightforward to access them. The main goal of this proposal is to substantially contribute to the current progress of the emerging field of topological quantum effects with a strong link to experimental activity carried out in this area. One of the focus of our proposal lies on atomic magnetic chains on superconducting surfaces. Here, we are motivated by recent experiments in Princeton and at my home institution that observed the first signature of Majorana bound states. However, their interpretation is still under intense debate by leading experts worldwide as many effects were not taken into account in the first theoretical analyses. The systematic analytical and numerical studies are of great importance for this growing field of activities. Moreover, the strategy we pursue is not to focus on characterization of already existing systems but also to continue the search for the experimentally relevant systems with topological properties. By combining well-known ingredients, such as spin orbit interaction (intrinsic and synthetic), superconductivity, and electron-electron interactions, we plan to identify novel setups which can host topological excitations, in particular of non-Abelian character such as Ising or Fibonacci anyons. In particular, we plan to work on the following topics:2.A Single magnetic impurities on superconducting surfaces. Suppression of the local superconducting pairing amplitude, magnetic configuration of two spin impurities, pi junction, Shiba bound states, Andreev bound states.2.B Chains of magnetic impurities: generation and manipulation of Majorana bound states. RKKY systems and Majorana bound states, interpretation of recent experiments, proximity-induced superconductivity in atomic chains, localization lengths, local change of the topological criterion.2.C Edge states of two-dimensional topological insulators: Majorana bound states and parafermions. Local magnetic doping, spin filtering effects, fast spin-switches manipulated by electric fields, electron-electron interactions. 1 1 OverviewResearch Publications Projects & Collaborations
Projects & Collaborations 7 foundShow per page10 10 20 50 Open quantum many-body systems Research Project | 2 Project MembersImported from Grants Tool 4709943 CavitySuperTop: Cavity-induced superconductivity and topological states of matter Research Project | 1 Project MembersNo Description available 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 . 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. ETOPEX/Engineering Topological Phases and Excitations in Nanostructures Research Project | 1 Project MembersThe main goal of this theory project is to propose engineered topological phases emerging only in strongly interacting systems and to identify the most feasible systems for experimental implementation. First, we will focus on setups hosting topological states localized at domain walls in one-dimensional channels such as parafermions, which are a new class of non-Abelian anyons and most promising candidates for topological quantum computing schemes. Second, in the framework of weakly coupled wires and planes, we will develop schemes for novel fractional topological phases in two- and three-dimensional interacting systems. To achieve these two goals, my team will identify necessary ingredients such as strong electron-electron interactions, helical magnetic order, or crossed Andreev proximity-induced superconductivity and address each of them separately. Later, we combine them to lead us to the desired topological phases and states. On our way to the main goal, as test cases, we will also study non-interacting analogies of the proposed effects such as Majorana fermions and integer topological insulators and pay close attention to the rapid experimental progress to come up with the most feasible proposals. We will study transport properties, scanning tunneling and atomic force microscopy. Especially for systems driven out of equilibrium, we will develop a Floquet-Luttinger liquid technique. We will explore the stability of engineered topological phases, error rates of topological qubits based on them, and computation schemes allowing for a set of universal qubit gates. We will strive to find a reasonable balance between topological stability and experimental feasibility of setups. Our main theoretical tools are Luttinger liquid techniques (bosonization and renormalization group), Green functions, Floquet formalism, and numerical simulations in non-interacting test models. Topological quantum bound states: Shiba, Majorana, and parafermions bound states Research Project | 7 Project MembersThe present proposal focuses on topological quantum effects in condensed matter physics. Topological quantum effects is a relatively young field, however, it has the potential to become an essential part of future technology. The field began with purely theoretical proposals on topologically protected quantum computation schemes, however, in a very short time, first seminal experiments demonstrating signatures of topological insulators and Majorana bound states were carried out. These pioneering experiments give us hope that indeed topological effects and their unique stability to local perturbations exist in Nature even if it is not so straightforward to access them. The main goal of this proposal is to substantially contribute to the current progress of the emerging field of topological quantum effects with a strong link to experimental activity carried out in this area. One of the focus of our proposal lies on atomic magnetic chains on superconducting surfaces. Here, we are motivated by recent experiments in Princeton and at my home institution that observed the first signature of Majorana bound states. However, their interpretation is still under intense debate by leading experts worldwide as many effects were not taken into account in the first theoretical analyses. The systematic analytical and numerical studies are of great importance for this growing field of activities. Moreover, the strategy we pursue is not to focus on characterization of already existing systems but also to continue the search for the experimentally relevant systems with topological properties. By combining well-known ingredients, such as spin orbit interaction (intrinsic and synthetic), superconductivity, and electron-electron interactions, we plan to identify novel setups which can host topological excitations, in particular of non-Abelian character such as Ising or Fibonacci anyons. In particular, we plan to work on the following topics:2.A Single magnetic impurities on superconducting surfaces. Suppression of the local superconducting pairing amplitude, magnetic configuration of two spin impurities, pi junction, Shiba bound states, Andreev bound states.2.B Chains of magnetic impurities: generation and manipulation of Majorana bound states. RKKY systems and Majorana bound states, interpretation of recent experiments, proximity-induced superconductivity in atomic chains, localization lengths, local change of the topological criterion.2.C Edge states of two-dimensional topological insulators: Majorana bound states and parafermions. Local magnetic doping, spin filtering effects, fast spin-switches manipulated by electric fields, electron-electron interactions. 1 1
CavitySuperTop: Cavity-induced superconductivity and topological states of matter Research Project | 1 Project MembersNo Description available
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 .
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.
ETOPEX/Engineering Topological Phases and Excitations in Nanostructures Research Project | 1 Project MembersThe main goal of this theory project is to propose engineered topological phases emerging only in strongly interacting systems and to identify the most feasible systems for experimental implementation. First, we will focus on setups hosting topological states localized at domain walls in one-dimensional channels such as parafermions, which are a new class of non-Abelian anyons and most promising candidates for topological quantum computing schemes. Second, in the framework of weakly coupled wires and planes, we will develop schemes for novel fractional topological phases in two- and three-dimensional interacting systems. To achieve these two goals, my team will identify necessary ingredients such as strong electron-electron interactions, helical magnetic order, or crossed Andreev proximity-induced superconductivity and address each of them separately. Later, we combine them to lead us to the desired topological phases and states. On our way to the main goal, as test cases, we will also study non-interacting analogies of the proposed effects such as Majorana fermions and integer topological insulators and pay close attention to the rapid experimental progress to come up with the most feasible proposals. We will study transport properties, scanning tunneling and atomic force microscopy. Especially for systems driven out of equilibrium, we will develop a Floquet-Luttinger liquid technique. We will explore the stability of engineered topological phases, error rates of topological qubits based on them, and computation schemes allowing for a set of universal qubit gates. We will strive to find a reasonable balance between topological stability and experimental feasibility of setups. Our main theoretical tools are Luttinger liquid techniques (bosonization and renormalization group), Green functions, Floquet formalism, and numerical simulations in non-interacting test models.
Topological quantum bound states: Shiba, Majorana, and parafermions bound states Research Project | 7 Project MembersThe present proposal focuses on topological quantum effects in condensed matter physics. Topological quantum effects is a relatively young field, however, it has the potential to become an essential part of future technology. The field began with purely theoretical proposals on topologically protected quantum computation schemes, however, in a very short time, first seminal experiments demonstrating signatures of topological insulators and Majorana bound states were carried out. These pioneering experiments give us hope that indeed topological effects and their unique stability to local perturbations exist in Nature even if it is not so straightforward to access them. The main goal of this proposal is to substantially contribute to the current progress of the emerging field of topological quantum effects with a strong link to experimental activity carried out in this area. One of the focus of our proposal lies on atomic magnetic chains on superconducting surfaces. Here, we are motivated by recent experiments in Princeton and at my home institution that observed the first signature of Majorana bound states. However, their interpretation is still under intense debate by leading experts worldwide as many effects were not taken into account in the first theoretical analyses. The systematic analytical and numerical studies are of great importance for this growing field of activities. Moreover, the strategy we pursue is not to focus on characterization of already existing systems but also to continue the search for the experimentally relevant systems with topological properties. By combining well-known ingredients, such as spin orbit interaction (intrinsic and synthetic), superconductivity, and electron-electron interactions, we plan to identify novel setups which can host topological excitations, in particular of non-Abelian character such as Ising or Fibonacci anyons. In particular, we plan to work on the following topics:2.A Single magnetic impurities on superconducting surfaces. Suppression of the local superconducting pairing amplitude, magnetic configuration of two spin impurities, pi junction, Shiba bound states, Andreev bound states.2.B Chains of magnetic impurities: generation and manipulation of Majorana bound states. RKKY systems and Majorana bound states, interpretation of recent experiments, proximity-induced superconductivity in atomic chains, localization lengths, local change of the topological criterion.2.C Edge states of two-dimensional topological insulators: Majorana bound states and parafermions. Local magnetic doping, spin filtering effects, fast spin-switches manipulated by electric fields, electron-electron interactions.
