Prof. Dr. Christoph Bruder Department of Physics Profiles & Affiliations OverviewResearch Publications Projects & Collaborations Projects & Collaborations OverviewResearch Publications Projects & Collaborations Profiles & Affiliations Projects & Collaborations 14 foundShow per page10 10 20 50 Hybrid quantum-classical neural networks for the characterization of noisy intermediate scale quantum computers Research Project | 1 Project MembersNo Description available Quantum synchronization and quantum phase transitions in arrays of nano- and optomechanical systems Research Project | 1 Project MembersWe will explore novel aspects of quantum synchronization in networks of self-sustained oscillators. This includes even-odd effects in the number of levels of the synchronization nodes and the dependence on network topology (number of neighbors and interaction range). Another interesting direction that we will study is frustration effects and possible links to frustrated quantum spin systems. Furthermore, we will investigate symmetry-breaking pattern formation in synchronization networks Using unsupervised machine-learning schemes, we will investigate phase diagrams of models that exhibit synchronization or other types of long-range order. We will also explore neural network architectures that involve physical insights and recent innovations in machine learning to compute steady states of driven dissipative quantum systems. Quantum coherence, quantum statistics, and superconductivity in mesoscopic systems Research Project | 1 Project MembersA. Quantum coherence and statistics of mesoscopic system We will explore novel nano- and optomechanical setups and their applications (phononic structures, combined photonic and phononic crystals, quantum dots embedded in nanowires, and trapped ions). We will propose and analyze new transport experiments with ultracold atoms, e.g. addressing the question of the phase dependence of heat transport. We will analyze models that illustrate how system-mediated detector-detector interactions will determine the measured operator order in a quantum correlation measurement. B. Mesoscopic superconductivity We will investigate a quantum realization of the Kuramoto model in a one-dimensional Josephson array. Using a tight-binding approach we will explore the influence of magnetic disorder on the disorder-induced 2D topological insulator state, the so-called topological Anderson insulator. Lastly, we will investigate the possibility to use superconducting transmon qubits as an implementation of driven anharmonic self-oscillators. This would lead to applications in the study of dissipative quantum phase transitions. NCCR QSIT: Quantum Sensing Research Project | 7 Project MembersThe readout of quantum states is part of any quantum information proces- sor and the question of a quantum measurement is a central one in quantum mechanics. In Project 1 we focus on quantum sensing - that is the development of well characterized quantum systems that will be used to probe either ultra-weak classical fields or complex quantum systems. Single qubits or oscillators designed and perfected to have ultra-long coherence times can be extremely sensitive to small electric or magnetic fields. QSIT researchers will use cutting-edge nano-technology to fully exploit the power of systems such as nano-mechanical oscil lators or nitrogen-vacancy (NV) centers in diamond, to engineer ultimate "quantum meters". NCCR QSIT: Quantum Simulation Research Project | 1 Project MembersProject 4 focuses on the realization of quantum simulators. While the ultimate goal is the physical realization of condensed-matter models that can- not be solved using classical computers the realization of topological states using ultra-cold bosonic or fermionic atoms will also be pursued. Quantum coherence, quantum statistics, and superconductivity Research Project | 3 Project MembersThe physics of mesoscopic quantum systems, i.e., electronic structures in the nanometer range, is one of the most active research areas of condensed-matter physics. These systems allow us to study fundamental physics questions, and their understanding is necessary for possible future electronic device applications. The goal of our research is to exploit and analyze quantum effects in such circuits, e.g. novel excitations like Majorana quasiparticles. These particles have been predicted but not yet been found in particle physics. Another interesting field that we work on is generalized quantum measurements and quantum model systems that can be used to test the foundations and limits of quantum mechanics. In particular, our group (about 3 PhD students and 3 Postdocs) plans to study the interplay of electric currents through nanostructures with mechanical degrees of freedom (nanomechanics). We are also interested in fluctuation and noise phenomena: electrical currents are not exactly constant but fluctuate, and these fluctuations contain a great deal of information about the quantum nature of the electrons that carry the current. We will also investigate ultracold atoms which can be used to study quantum coherence and quantum many-body phenomena. Finally, we study macroscopic quantum phenomena like superconductivity. Cooling, Amplification, and Lasing in the reversed dissipation regime of cavity Research Project | 2 Project MembersP { margin-bottom: 0.08in; direction: ltr; color: rgb(0, 0, 0); widows: 2; orphans: 2; }P.western { } Cavity optomechanical phenomena, e.g. cooling, amplification or optomechanically-induced transparency, emerge due a stark imbalance between the dissipation rates of the optical and mechanical degrees of freedom. However, it has been an unquestioned assumption that the mechanical damping rate is much smaller than optical dissipation rate. Our goal is to investigate the regime of reversed dissipation hierarchy where the mechanical damping rate is much larger than the optical line width. We will show that this regime can be exploited for cooling and amplifying microwave signals and leads to novel lasing phenomena. The project will be carried out in close collaboration with the group of Tobias Kippenberg, in particular between Andreas Nunnenkamp (Basel) and Vivishek Sudhir (EPFL). Quantum coherence, quantum statistics, and superconductivity in mesoscopic systems Research Project | 1 Project MembersThe physics of mesoscopic systems, i.e., electronic structures in the nanometer range, is one of the most active research areas of condensed-matter physics. These systems allow us to study fundamental physics questions, and their understanding is a necessary prerequisite for possible future electronic device applications. The goal of our research is to exploit and analyze quantum interference effects in such electronic circuits. In the last couple of years, new exciting areas have opened up, like nanomechanics, or the interface of ultracold atoms and condensed-matter systems. In particular, our group (about 3 PhD students and 3 Postdocs) plans to study the interplay of electric currents through nanostructures with mechanical degrees of freedom (nanomechanics). We are also interested in fluctuation and noise phenomena: electrical currents are not exactly constant but fluctuate, and these fluctuations contain a great deal of information about the quantum nature of the electrons that carry the current. We will also investigate ultracold atoms which can be used to study quantum coherence and quantum many-body phenomena. Cold atoms can be trapped in so-called optical lattices and show similarities to electrons in a crystal lattice. The great advantage of cold atoms is that the properties of the lattice can be controlled much more easily than in the case of a crystal lattice. Finally, we are also interested in the foundations of quantum mechanics (entanglement, weak measurements in solid-state systems). Atoms and Molecules in Lattices: New Approaches to Quantum Simulation TP1 Research Project | 3 Project MembersThere is great deal of interest in the interface between cold atoms and condensed-matter physics. On the one hand, the fact that the parameters of optical lattices can be tuned in a wide range allows the investigation of condensed-matter phenomena like phase transitions. On the other hand, optical lattices offer the possibility to study new phenomena unknown in traditional condensed-matter physics. Cavity Optomechanics - Quantum Measurements and Backaction TP1 Research Project | 2 Project MembersThe goal of this theoretical subproject is to analyze existing and new setups of nanomechanical and optomechanical systems and to propose and investigate ways to generate and measure new quantum states. The mechanical systems considered include cantilevers, membranes, and also non-traditional types of oscillators like collective density excitations of a Bose-Einstein condensate coupled to a cavity field. 12 12 OverviewResearch Publications Projects & Collaborations
Projects & Collaborations 14 foundShow per page10 10 20 50 Hybrid quantum-classical neural networks for the characterization of noisy intermediate scale quantum computers Research Project | 1 Project MembersNo Description available Quantum synchronization and quantum phase transitions in arrays of nano- and optomechanical systems Research Project | 1 Project MembersWe will explore novel aspects of quantum synchronization in networks of self-sustained oscillators. This includes even-odd effects in the number of levels of the synchronization nodes and the dependence on network topology (number of neighbors and interaction range). Another interesting direction that we will study is frustration effects and possible links to frustrated quantum spin systems. Furthermore, we will investigate symmetry-breaking pattern formation in synchronization networks Using unsupervised machine-learning schemes, we will investigate phase diagrams of models that exhibit synchronization or other types of long-range order. We will also explore neural network architectures that involve physical insights and recent innovations in machine learning to compute steady states of driven dissipative quantum systems. Quantum coherence, quantum statistics, and superconductivity in mesoscopic systems Research Project | 1 Project MembersA. Quantum coherence and statistics of mesoscopic system We will explore novel nano- and optomechanical setups and their applications (phononic structures, combined photonic and phononic crystals, quantum dots embedded in nanowires, and trapped ions). We will propose and analyze new transport experiments with ultracold atoms, e.g. addressing the question of the phase dependence of heat transport. We will analyze models that illustrate how system-mediated detector-detector interactions will determine the measured operator order in a quantum correlation measurement. B. Mesoscopic superconductivity We will investigate a quantum realization of the Kuramoto model in a one-dimensional Josephson array. Using a tight-binding approach we will explore the influence of magnetic disorder on the disorder-induced 2D topological insulator state, the so-called topological Anderson insulator. Lastly, we will investigate the possibility to use superconducting transmon qubits as an implementation of driven anharmonic self-oscillators. This would lead to applications in the study of dissipative quantum phase transitions. NCCR QSIT: Quantum Sensing Research Project | 7 Project MembersThe readout of quantum states is part of any quantum information proces- sor and the question of a quantum measurement is a central one in quantum mechanics. In Project 1 we focus on quantum sensing - that is the development of well characterized quantum systems that will be used to probe either ultra-weak classical fields or complex quantum systems. Single qubits or oscillators designed and perfected to have ultra-long coherence times can be extremely sensitive to small electric or magnetic fields. QSIT researchers will use cutting-edge nano-technology to fully exploit the power of systems such as nano-mechanical oscil lators or nitrogen-vacancy (NV) centers in diamond, to engineer ultimate "quantum meters". NCCR QSIT: Quantum Simulation Research Project | 1 Project MembersProject 4 focuses on the realization of quantum simulators. While the ultimate goal is the physical realization of condensed-matter models that can- not be solved using classical computers the realization of topological states using ultra-cold bosonic or fermionic atoms will also be pursued. Quantum coherence, quantum statistics, and superconductivity Research Project | 3 Project MembersThe physics of mesoscopic quantum systems, i.e., electronic structures in the nanometer range, is one of the most active research areas of condensed-matter physics. These systems allow us to study fundamental physics questions, and their understanding is necessary for possible future electronic device applications. The goal of our research is to exploit and analyze quantum effects in such circuits, e.g. novel excitations like Majorana quasiparticles. These particles have been predicted but not yet been found in particle physics. Another interesting field that we work on is generalized quantum measurements and quantum model systems that can be used to test the foundations and limits of quantum mechanics. In particular, our group (about 3 PhD students and 3 Postdocs) plans to study the interplay of electric currents through nanostructures with mechanical degrees of freedom (nanomechanics). We are also interested in fluctuation and noise phenomena: electrical currents are not exactly constant but fluctuate, and these fluctuations contain a great deal of information about the quantum nature of the electrons that carry the current. We will also investigate ultracold atoms which can be used to study quantum coherence and quantum many-body phenomena. Finally, we study macroscopic quantum phenomena like superconductivity. Cooling, Amplification, and Lasing in the reversed dissipation regime of cavity Research Project | 2 Project MembersP { margin-bottom: 0.08in; direction: ltr; color: rgb(0, 0, 0); widows: 2; orphans: 2; }P.western { } Cavity optomechanical phenomena, e.g. cooling, amplification or optomechanically-induced transparency, emerge due a stark imbalance between the dissipation rates of the optical and mechanical degrees of freedom. However, it has been an unquestioned assumption that the mechanical damping rate is much smaller than optical dissipation rate. Our goal is to investigate the regime of reversed dissipation hierarchy where the mechanical damping rate is much larger than the optical line width. We will show that this regime can be exploited for cooling and amplifying microwave signals and leads to novel lasing phenomena. The project will be carried out in close collaboration with the group of Tobias Kippenberg, in particular between Andreas Nunnenkamp (Basel) and Vivishek Sudhir (EPFL). Quantum coherence, quantum statistics, and superconductivity in mesoscopic systems Research Project | 1 Project MembersThe physics of mesoscopic systems, i.e., electronic structures in the nanometer range, is one of the most active research areas of condensed-matter physics. These systems allow us to study fundamental physics questions, and their understanding is a necessary prerequisite for possible future electronic device applications. The goal of our research is to exploit and analyze quantum interference effects in such electronic circuits. In the last couple of years, new exciting areas have opened up, like nanomechanics, or the interface of ultracold atoms and condensed-matter systems. In particular, our group (about 3 PhD students and 3 Postdocs) plans to study the interplay of electric currents through nanostructures with mechanical degrees of freedom (nanomechanics). We are also interested in fluctuation and noise phenomena: electrical currents are not exactly constant but fluctuate, and these fluctuations contain a great deal of information about the quantum nature of the electrons that carry the current. We will also investigate ultracold atoms which can be used to study quantum coherence and quantum many-body phenomena. Cold atoms can be trapped in so-called optical lattices and show similarities to electrons in a crystal lattice. The great advantage of cold atoms is that the properties of the lattice can be controlled much more easily than in the case of a crystal lattice. Finally, we are also interested in the foundations of quantum mechanics (entanglement, weak measurements in solid-state systems). Atoms and Molecules in Lattices: New Approaches to Quantum Simulation TP1 Research Project | 3 Project MembersThere is great deal of interest in the interface between cold atoms and condensed-matter physics. On the one hand, the fact that the parameters of optical lattices can be tuned in a wide range allows the investigation of condensed-matter phenomena like phase transitions. On the other hand, optical lattices offer the possibility to study new phenomena unknown in traditional condensed-matter physics. Cavity Optomechanics - Quantum Measurements and Backaction TP1 Research Project | 2 Project MembersThe goal of this theoretical subproject is to analyze existing and new setups of nanomechanical and optomechanical systems and to propose and investigate ways to generate and measure new quantum states. The mechanical systems considered include cantilevers, membranes, and also non-traditional types of oscillators like collective density excitations of a Bose-Einstein condensate coupled to a cavity field. 12 12
Hybrid quantum-classical neural networks for the characterization of noisy intermediate scale quantum computers Research Project | 1 Project MembersNo Description available
Quantum synchronization and quantum phase transitions in arrays of nano- and optomechanical systems Research Project | 1 Project MembersWe will explore novel aspects of quantum synchronization in networks of self-sustained oscillators. This includes even-odd effects in the number of levels of the synchronization nodes and the dependence on network topology (number of neighbors and interaction range). Another interesting direction that we will study is frustration effects and possible links to frustrated quantum spin systems. Furthermore, we will investigate symmetry-breaking pattern formation in synchronization networks Using unsupervised machine-learning schemes, we will investigate phase diagrams of models that exhibit synchronization or other types of long-range order. We will also explore neural network architectures that involve physical insights and recent innovations in machine learning to compute steady states of driven dissipative quantum systems.
Quantum coherence, quantum statistics, and superconductivity in mesoscopic systems Research Project | 1 Project MembersA. Quantum coherence and statistics of mesoscopic system We will explore novel nano- and optomechanical setups and their applications (phononic structures, combined photonic and phononic crystals, quantum dots embedded in nanowires, and trapped ions). We will propose and analyze new transport experiments with ultracold atoms, e.g. addressing the question of the phase dependence of heat transport. We will analyze models that illustrate how system-mediated detector-detector interactions will determine the measured operator order in a quantum correlation measurement. B. Mesoscopic superconductivity We will investigate a quantum realization of the Kuramoto model in a one-dimensional Josephson array. Using a tight-binding approach we will explore the influence of magnetic disorder on the disorder-induced 2D topological insulator state, the so-called topological Anderson insulator. Lastly, we will investigate the possibility to use superconducting transmon qubits as an implementation of driven anharmonic self-oscillators. This would lead to applications in the study of dissipative quantum phase transitions.
NCCR QSIT: Quantum Sensing Research Project | 7 Project MembersThe readout of quantum states is part of any quantum information proces- sor and the question of a quantum measurement is a central one in quantum mechanics. In Project 1 we focus on quantum sensing - that is the development of well characterized quantum systems that will be used to probe either ultra-weak classical fields or complex quantum systems. Single qubits or oscillators designed and perfected to have ultra-long coherence times can be extremely sensitive to small electric or magnetic fields. QSIT researchers will use cutting-edge nano-technology to fully exploit the power of systems such as nano-mechanical oscil lators or nitrogen-vacancy (NV) centers in diamond, to engineer ultimate "quantum meters".
NCCR QSIT: Quantum Simulation Research Project | 1 Project MembersProject 4 focuses on the realization of quantum simulators. While the ultimate goal is the physical realization of condensed-matter models that can- not be solved using classical computers the realization of topological states using ultra-cold bosonic or fermionic atoms will also be pursued.
Quantum coherence, quantum statistics, and superconductivity Research Project | 3 Project MembersThe physics of mesoscopic quantum systems, i.e., electronic structures in the nanometer range, is one of the most active research areas of condensed-matter physics. These systems allow us to study fundamental physics questions, and their understanding is necessary for possible future electronic device applications. The goal of our research is to exploit and analyze quantum effects in such circuits, e.g. novel excitations like Majorana quasiparticles. These particles have been predicted but not yet been found in particle physics. Another interesting field that we work on is generalized quantum measurements and quantum model systems that can be used to test the foundations and limits of quantum mechanics. In particular, our group (about 3 PhD students and 3 Postdocs) plans to study the interplay of electric currents through nanostructures with mechanical degrees of freedom (nanomechanics). We are also interested in fluctuation and noise phenomena: electrical currents are not exactly constant but fluctuate, and these fluctuations contain a great deal of information about the quantum nature of the electrons that carry the current. We will also investigate ultracold atoms which can be used to study quantum coherence and quantum many-body phenomena. Finally, we study macroscopic quantum phenomena like superconductivity.
Cooling, Amplification, and Lasing in the reversed dissipation regime of cavity Research Project | 2 Project MembersP { margin-bottom: 0.08in; direction: ltr; color: rgb(0, 0, 0); widows: 2; orphans: 2; }P.western { } Cavity optomechanical phenomena, e.g. cooling, amplification or optomechanically-induced transparency, emerge due a stark imbalance between the dissipation rates of the optical and mechanical degrees of freedom. However, it has been an unquestioned assumption that the mechanical damping rate is much smaller than optical dissipation rate. Our goal is to investigate the regime of reversed dissipation hierarchy where the mechanical damping rate is much larger than the optical line width. We will show that this regime can be exploited for cooling and amplifying microwave signals and leads to novel lasing phenomena. The project will be carried out in close collaboration with the group of Tobias Kippenberg, in particular between Andreas Nunnenkamp (Basel) and Vivishek Sudhir (EPFL).
Quantum coherence, quantum statistics, and superconductivity in mesoscopic systems Research Project | 1 Project MembersThe physics of mesoscopic systems, i.e., electronic structures in the nanometer range, is one of the most active research areas of condensed-matter physics. These systems allow us to study fundamental physics questions, and their understanding is a necessary prerequisite for possible future electronic device applications. The goal of our research is to exploit and analyze quantum interference effects in such electronic circuits. In the last couple of years, new exciting areas have opened up, like nanomechanics, or the interface of ultracold atoms and condensed-matter systems. In particular, our group (about 3 PhD students and 3 Postdocs) plans to study the interplay of electric currents through nanostructures with mechanical degrees of freedom (nanomechanics). We are also interested in fluctuation and noise phenomena: electrical currents are not exactly constant but fluctuate, and these fluctuations contain a great deal of information about the quantum nature of the electrons that carry the current. We will also investigate ultracold atoms which can be used to study quantum coherence and quantum many-body phenomena. Cold atoms can be trapped in so-called optical lattices and show similarities to electrons in a crystal lattice. The great advantage of cold atoms is that the properties of the lattice can be controlled much more easily than in the case of a crystal lattice. Finally, we are also interested in the foundations of quantum mechanics (entanglement, weak measurements in solid-state systems).
Atoms and Molecules in Lattices: New Approaches to Quantum Simulation TP1 Research Project | 3 Project MembersThere is great deal of interest in the interface between cold atoms and condensed-matter physics. On the one hand, the fact that the parameters of optical lattices can be tuned in a wide range allows the investigation of condensed-matter phenomena like phase transitions. On the other hand, optical lattices offer the possibility to study new phenomena unknown in traditional condensed-matter physics.
Cavity Optomechanics - Quantum Measurements and Backaction TP1 Research Project | 2 Project MembersThe goal of this theoretical subproject is to analyze existing and new setups of nanomechanical and optomechanical systems and to propose and investigate ways to generate and measure new quantum states. The mechanical systems considered include cantilevers, membranes, and also non-traditional types of oscillators like collective density excitations of a Bose-Einstein condensate coupled to a cavity field.
