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Technical Physics

Prof. Rudolf Gross, Prof. Stefan Filipp

Research Field

The research activities of the Walther-Meißner-Institute are focused on low temperature solid-state and condensed matter physics. The research program is devoted to both fundamental and applied research and also addresses materials science, thin film and nanotechnology aspects. With respect to basic research the main focus of the WMI is on

  • superconductivity and superfluidity,
  • magnetism, spin transport, and spin caloritronics,
  • quantum phenomena in mesoscopic systems and nanostructures,
  • quantum technology and quantum computing,
  • and the general properties of metallic systems at low and very low temperatures.

The WMI also conducts applied research in the fields of

  • solid-state quantum information processing systems,
  • superconducting and spintronic devices,
  • oxide electronics,
  • multi-functional and multiferroic materials,
  • and the development of low and ultra low temperature systems and techniques.

With respect to materials science, thin film and nanotechnology the research program is focused on

  • the synthesis of superconducting and magnetic materials,,
  • the single crystal growth of oxide materials,
  • the thin film technology of complex oxide heterostructures including multi-functional and multiferroic material systems,
  • the fabrication of superconducting, magnetic, and hybrid nanostructures,
  • and the growth of self-organized molecular ad-layers.

The WMI also develops and operates systems and techniques for low and ultra-low temperature experiments. A recent development are dry mK-systems that can be operated without liquid helium by using a pulse-tube refrigerator for precooling. Meanwhile, these systems have been successfully commercialized by the company VeriCold Technologies GmbH at Ismaning, Germany, which meanwhile has been acquired by Oxford Instruments. As further typical examples we mention a nuclear demagnetization cryostat for temperature down to below 100µK, or very flexible dilution refrigerator inserts for temperatures down to about 20mK fitting into a 2inch bore. These systems have been engineered and fabricated at the WMI. Within the last years, several dilution refrigerators have been provided to other research groups for various low temperature experiments. The WMI also operates a helium liquifier with a capacity of more than 150.000 liters per year and supplies both Munich universities with liquid helium. To optimize the transfer of liquid helium into transport containers the WMI has developed a pumping system for liquid helium that is commercialized in collaboration with a company.

Address/Contact

Walther-Meißner-Straße 8
85748 Garching b. München
+49 (89) 289 - 14202
Fax: +49 (89) 289 - 14206

Members of the Research Group

Professors

Office

Scientists

Other Staff

Teaching

Course with Participations of Group Members

Titel und Modulzuordnung
ArtSWSDozent(en)Termine
Applied Superconductivity 1: from Josephson Effects to RSFQ Logic
LV-Unterlagen
Zuordnung zu Modulen:
VO 2 Fedorov, K. Mi, 14:15–15:45, WMI 143
Magnetism
eLearning-Kurs LV-Unterlagen
Zuordnung zu Modulen:
VO 2 Kukharchyk, N. Di, 14:00–15:30, WMI 143
QST Experiment: Quantum Hardware
Zuordnung zu Modulen:
VO 4 Filipp, S. Do, 16:00–18:00, PH HS1
Fr, 08:00–10:00, PH HS1
Quantum Sensing
Zuordnung zu Modulen:
VO 2 Brandt, M. Bucher, D. Hübl, H. Mi, 10:00–12:00, ZNN 0.001
Superconductivity and Low Temperature Physics 1
eLearning-Kurs LV-Unterlagen
Zuordnung zu Modulen:
VO 2 Gross, R. Do, 12:00–14:00, PH HS3
Fortschritte in der Festkörperphysik
LV-Unterlagen virtueller Hörsaal
Zuordnung zu Modulen:
PS 2 Gross, R. Di, 10:15–11:30, virtuell
Quantum Entrepreneurship Laboratory
Zuordnung zu Modulen:
HS 2 Filipp, S. Mendl, C.
Mitwirkende: Cerda Sevilla, M.Trummer, C.
Spin Currents and Skyrmionics
LV-Unterlagen
Zuordnung zu Modulen:
PS 2 Hübl, H.
Mitwirkende: Althammer, M.Geprägs, S.Opel, M.
Do, 14:00–15:30, WMI 142
Supraleitende Quantenschaltkreise
LV-Unterlagen virtueller Hörsaal
Zuordnung zu Modulen:
PS 2 Deppe, F. Filipp, S.
Leitung/Koordination: Gross, R.
Mitwirkende: Fedorov, K.Marx, A.
Termine in Gruppen
Topical Issues in Magneto- and Spin Electronics
LV-Unterlagen
Zuordnung zu Modulen:
HS 2 Brandt, M. Hübl, H.
Mitwirkende: Althammer, M.Geprägs, S.
Mi, 11:30–13:00, WSI S101
Exercise to Applied Superconductivity 1: from Josephson Effects to RSFQ Logic
Zuordnung zu Modulen:
UE 2
Leitung/Koordination: Fedorov, K.
Termine in Gruppen
Exercise to Magnetism
eLearning-Kurs LV-Unterlagen
Zuordnung zu Modulen:
UE 1 Kukharchyk, N. Termine in Gruppen
Exercise to QST Experiment: Quantum Hardware
Zuordnung zu Modulen:
UE 2
Leitung/Koordination: Filipp, S.
Termine in Gruppen
Übung zu Supraleitung und Tieftemperaturphysik 1
eLearning-Kurs LV-Unterlagen
Zuordnung zu Modulen:
UE 2 Gross, R. Termine in Gruppen
Festkörperkolloquium
aktuelle Informationen
Zuordnung zu Modulen:
KO 2 Gross, R. Do, 17:00–19:00, PH HS3
FOPRA Experiment 104: The Josephson Parametric Amplifier (JPA) (QST-EX)
LV-Unterlagen
Zuordnung zu Modulen:
PR 1 Fedorov, K. Krueger, P.
Leitung/Koordination: Gross, R.
FOPRA Experiment 108: Qubit Control and Characterization for Superconducting Quantum Processors (AEP, KM, QST-EX)
Zuordnung zu Modulen:
PR 1 Tsitsilin, I. Wallner, F.
Leitung/Koordination: Filipp, S.
FOPRA Experiment 16: Josephson Effects in Superconductors (AEP, KM, QST-EX)
LV-Unterlagen aktuelle Informationen
Zuordnung zu Modulen:
PR 1 Chen, Q. Nojiri, Y.
Leitung/Koordination: Gross, R.
Journal Club on Quantum Systems
Zuordnung zu Modulen:
SE 2 Filipp, S. Mi, 09:00–11:00, WMI 143
Repetitorium zu Aktuelle Themen der Magneto- und Spinelektronik
Zuordnung zu Modulen:
RE 2
Leitung/Koordination: Hübl, H.
Repetitorium zu Fortschritte in der Festkörperphysik
Zuordnung zu Modulen:
RE 2
Leitung/Koordination: Gross, R.
Repetitorium zu Quanten-Entrepreneurship-Labor
Zuordnung zu Modulen:
RE 2
Leitung/Koordination: Filipp, S.
Repetitorium zu Spin-Ströme und Skyrmionik
Zuordnung zu Modulen:
RE 2
Leitung/Koordination: Hübl, H.
Repetitorium zu Supraleitende Quantenschaltkreise
Zuordnung zu Modulen:
RE 2
Leitung/Koordination: Gross, R.
Walther-Meißner-Seminar on Topical Problems of Low Temperature Physics
aktuelle Informationen
Zuordnung zu Modulen:
SE 2 Filipp, S. Gross, R. Termine in Gruppen

Offers for Theses in the Group

Dynamical decoupling and noise spectroscopy with superconducting qubits
The characterization and mitigation of decoherence sources in qubits is crucial for quantum computing applications. Decoherence of a quantum superposition state arises from the interaction between the system and the uncontrolled degrees of freedom in its environment. The qubit decoherence is characterized by two rates: a longitudinal relaxation rate Γ1 due to the exchange of energy with the environment, and a transverse relaxation rate Γ2 = Γ1/2 + Γϕ which contains the pure dephasing rate Γϕ. Irreversible energy relaxation can only be mitigated by reducing the amount of environmental noise, reducing the qubit’s internal sensitivity to that noise, or through multi-qubit encoding and error correction protocols. In contrast, dephasing is in principle reversible and can be refocused dynamically through the application of coherent control pulse methods. In this work we are going to investigate different sources of noise and decoherence and how dynamical-decoupling techniques such as CPMG can change the dephasing effects of low-frequency noise on a superconducting qubit.
suitable as
  • Bachelor’s Thesis Physics
Supervisor: Stefan Filipp
Fabrication of a superconducting coplanar transmission line for efficient coupling to rare earth spin ensembles
The rare earth spin ensembles are well established by now in the optical domain where the microwave states are used as an intermediate state to extend the storage time [1]. Number of purely microwave manipulations by spin ensembles is very limited and is bound to coupling of spin ensembles to microwave resonating structures [2], which allows amplifying the microwave signal and enhancing the interaction between the ions and the microwave field. The main disadvantage of using these resonating structures is their fixed frequencies and very small tuning range. Typically fabricated in a coplanar design, the superconducting resonators create strongly inhomogeneous distribution of the field within the spin ensemble, which results into largely detuned Rabi frequencies experienced by the spins. Aim of this project is to fabricate novel design of microwave transmission line, which will allow for homogeneous distribution of the microwave field within the excited rare-earth spin ensemble, and at the same time, will not be bound to a specific frequency. This will allow realizing various spin manipulation schemes, which involve more than two energy levels (beyond Hahn-echo) and thus deploy complex spin-manipulation techniques. We are looking for a highly motivated master student joining this project. Within the project, you will gain hands-on experience on design and fabrication of superconducting microwave structures. You will design and fabricate superconducting transmission line, which will then be tested at cryogenic conditions when coupled to rare earth spins ensembles. [1] Kinos, A. et al. Roadmap for Rare-earth Quantum Computing. arXiv 2103.15743 (2021). [2] Ranjan, V. et al. Multimode Storage of Quantum Microwave Fields in Electron Spins over 100 ms. https://link.aps.org/doi/10.1103/PhysRevLett.125.210505 (2021).
suitable as
  • Master’s Thesis Quantum Science & Technology
Supervisor: Rudolf Gross
Fabrication of a superconducting coplanar transmission line for efficient coupling to rare earth spin ensembles
The rare earth spin ensembles are well established by now in the optical domain where the microwave states are used as an intermediate state to extend the storage time [1]. Number of purely microwave manipulations by spin ensembles is very limited and is bound to coupling of spin ensembles to microwave resonating structures [2], which allows amplifying the microwave signal and enhancing the interaction between the ions and the microwave field. The main disadvantage of using these resonating structures is their fixed frequencies and very small tuning range. Typically fabricated in a coplanar design, the superconducting resonators create strongly inhomogeneous distribution of the field within the spin ensemble, which results into largely detuned Rabi frequencies experienced by the spins. Aim of this project is to fabricate novel design of microwave transmission line, which will allow for homogeneous distribution of the microwave field within the excited rare-earth spin ensemble, and at the same time, will not be bound to a specific frequency. This will allow realizing various spin manipulation schemes, which involve more than two energy levels (beyond Hahn-echo) and thus deploy complex spin-manipulation techniques. We are looking for a highly motivated master student joining this project. Within the project, you will gain hands-on experience on design and fabrication of superconducting microwave structures. You will design and fabricate superconducting transmission line, which will then be tested at cryogenic conditions when coupled to rare earth spins ensembles. [1] Kinos, A. et al. Roadmap for Rare-earth Quantum Computing. arXiv 2103.15743 (2021). [2] Ranjan, V. et al. Multimode Storage of Quantum Microwave Fields in Electron Spins over 100 ms. https://link.aps.org/doi/10.1103/PhysRevLett.125.210505 (2021).
suitable as
  • Master’s Thesis Applied and Engineering Physics
Supervisor: Rudolf Gross
Fabrication of a superconducting coplanar transmission line for efficient coupling to rare earth spin ensembles
The rare earth spin ensembles are well established by now in the optical domain where the microwave states are used as an intermediate state to extend the storage time [1]. Number of purely microwave manipulations by spin ensembles is very limited and is bound to coupling of spin ensembles to microwave resonating structures [2], which allows amplifying the microwave signal and enhancing the interaction between the ions and the microwave field. The main disadvantage of using these resonating structures is their fixed frequencies and very small tuning range. Typically fabricated in a coplanar design, the superconducting resonators create strongly inhomogeneous distribution of the field within the spin ensemble, which results into largely detuned Rabi frequencies experienced by the spins. Aim of this project is to fabricate novel design of microwave transmission line, which will allow for homogeneous distribution of the microwave field within the excited rare-earth spin ensemble, and at the same time, will not be bound to a specific frequency. This will allow realizing various spin manipulation schemes, which involve more than two energy levels (beyond Hahn-echo) and thus deploy complex spin-manipulation techniques. We are looking for a highly motivated master student joining this project. Within the project, you will gain hands-on experience on design and fabrication of superconducting microwave structures. You will design and fabricate superconducting transmission line, which will then be tested at cryogenic conditions when coupled to rare earth spins ensembles. [1] Kinos, A. et al. Roadmap for Rare-earth Quantum Computing. arXiv 2103.15743 (2021). [2] Ranjan, V. et al. Multimode Storage of Quantum Microwave Fields in Electron Spins over 100 ms. https://link.aps.org/doi/10.1103/PhysRevLett.125.210505 (2021).
suitable as
  • Master’s Thesis Condensed Matter Physics
Supervisor: Rudolf Gross
Fabrication of a superconducting transmission line resonator in a bad-cavity limit
The rare earth spin ensembles are well established by now in the optical domain where the microwave states are used as an intermediate state to extend the storage time [1]. Number of purely microwave manipulations by spin ensembles is very limited and is bound to coupling of spin ensembles to microwave resonating structures [2], which allows amplifying the microwave signal and enhancing the interaction between the ions and the microwave field. The main disadvantage of using these resonating structures is their fixed frequencies and very small tuning range. Typically fabricated in a coplanar design, the superconducting resonators create strongly inhomogeneous distribution of the field within the spin ensemble, which results into largely detuned Rabi frequencies experienced by the spins. Aim of this project is to fabricate novel design of microwave transmission line resonator, which would work in a bad-cavity regime and will thus allow to couple to rare-earth spins at a larger badwidth. This will allow realizing various spin manipulation schemes, which involve more than two energy levels (beyond Hahn-echo) and thus deploy complex spin-manipulation techniques. We are looking for a highly motivated master student joining this project. Within the project, you will gain hands-on experience on design and fabrication of superconducting microwave structures. You will design and fabricate superconducting resonating structure, which will then be tested at cryogenic conditions when coupled to rare earth spins ensembles. [1] Kinos, A. et al. Roadmap for Rare-earth Quantum Computing. arXiv 2103.15743 (2021). [2] Ranjan, V. et al. Multimode Storage of Quantum Microwave Fields in Electron Spins over 100 ms. https://link.aps.org/doi/10.1103/PhysRevLett.125.210505 (2021).
suitable as
  • Master’s Thesis Quantum Science & Technology
Supervisor: Rudolf Gross
Fabrication of a superconducting transmission line resonator in a bad-cavity limit
The rare earth spin ensembles are well established by now in the optical domain where the microwave states are used as an intermediate state to extend the storage time [1]. Number of purely microwave manipulations by spin ensembles is very limited and is bound to coupling of spin ensembles to microwave resonating structures [2], which allows amplifying the microwave signal and enhancing the interaction between the ions and the microwave field. The main disadvantage of using these resonating structures is their fixed frequencies and very small tuning range. Typically fabricated in a coplanar design, the superconducting resonators create strongly inhomogeneous distribution of the field within the spin ensemble, which results into largely detuned Rabi frequencies experienced by the spins. Aim of this project is to fabricate novel design of microwave transmission line resonator, which would work in a bad-cavity regime and will thus allow to couple to rare-earth spins at a larger badwidth. This will allow realizing various spin manipulation schemes, which involve more than two energy levels (beyond Hahn-echo) and thus deploy complex spin-manipulation techniques. We are looking for a highly motivated master student joining this project. Within the project, you will gain hands-on experience on design and fabrication of superconducting microwave structures. You will design and fabricate superconducting resonating structure, which will then be tested at cryogenic conditions when coupled to rare earth spins ensembles. [1] Kinos, A. et al. Roadmap for Rare-earth Quantum Computing. arXiv 2103.15743 (2021). [2] Ranjan, V. et al. Multimode Storage of Quantum Microwave Fields in Electron Spins over 100 ms. https://link.aps.org/doi/10.1103/PhysRevLett.125.210505 (2021).
suitable as
  • Master’s Thesis Condensed Matter Physics
Supervisor: Rudolf Gross
Fabrication of a superconducting transmission line resonator in a bad-cavity limit
The rare earth spin ensembles are well established by now in the optical domain where the microwave states are used as an intermediate state to extend the storage time [1]. Number of purely microwave manipulations by spin ensembles is very limited and is bound to coupling of spin ensembles to microwave resonating structures [2], which allows amplifying the microwave signal and enhancing the interaction between the ions and the microwave field. The main disadvantage of using these resonating structures is their fixed frequencies and very small tuning range. Typically fabricated in a coplanar design, the superconducting resonators create strongly inhomogeneous distribution of the field within the spin ensemble, which results into largely detuned Rabi frequencies experienced by the spins. Aim of this project is to fabricate novel design of microwave transmission line resonator, which would work in a bad-cavity regime and will thus allow to couple to rare-earth spins at a larger badwidth. This will allow realizing various spin manipulation schemes, which involve more than two energy levels (beyond Hahn-echo) and thus deploy complex spin-manipulation techniques. We are looking for a highly motivated master student joining this project. Within the project, you will gain hands-on experience on design and fabrication of superconducting microwave structures. You will design and fabricate superconducting resonating structure, which will then be tested at cryogenic conditions when coupled to rare earth spins ensembles. [1] Kinos, A. et al. Roadmap for Rare-earth Quantum Computing. arXiv 2103.15743 (2021). [2] Ranjan, V. et al. Multimode Storage of Quantum Microwave Fields in Electron Spins over 100 ms. https://link.aps.org/doi/10.1103/PhysRevLett.125.210505 (2021).
suitable as
  • Master’s Thesis Applied and Engineering Physics
Supervisor: Rudolf Gross
Fabrication of low-loss Josephson parametric devices
Superconducting Josephson devices represent one of the leading hardware platforms of modern quantum information processing. In particular, these devices often employ nonlinear parametric effects for tunable coupling schemes or quantum-limited amplification. Such effects can be also used in a multitude of quantum communication & sensing protocols. In this context, a particular challenge arises due to the fundamental requirement for minimizing losses in superconducting systems in order to preserve the fragile quantum nature of related microwave states. To this end, one needs to develop advanced routines for fabrication of low-loss Josephson parametric amplifiers & parametric couplers by exploring various surface treatment approaches or studying novel superconducting materials. The low-loss Josephson devices are to be used in our ongoing experiments towards experimental investigation of particular novel concepts, such as the quantum radar or remote entanglement distribution protocols. This master thesis will involve designing superconducting parametric circuits, cleanroom fabrication, and characterization measurements of fabricated devices with an aim to employ these in microwave quantum communication & sensing experiments.
suitable as
  • Master’s Thesis Condensed Matter Physics
Supervisor: Rudolf Gross
Fabrication of low-loss Josephson parametric devices
Superconducting Josephson devices represent one of the leading hardware platforms of modern quantum information processing. In particular, these devices often employ nonlinear parametric effects for tunable coupling schemes or quantum-limited amplification. Such effects can be also used in a multitude of quantum communication & sensing protocols. In this context, a particular challenge arises due to the fundamental requirement for minimizing losses in superconducting systems in order to preserve the fragile quantum nature of related microwave states. To this end, one needs to develop advanced routines for fabrication of low-loss Josephson parametric amplifiers & parametric couplers by exploring various surface treatment approaches or studying novel superconducting materials. The low-loss Josephson devices are to be used in our ongoing experiments towards experimental investigation of particular novel concepts, such as the quantum radar or remote entanglement distribution protocols. This master thesis will involve designing superconducting parametric circuits, cleanroom fabrication, and characterization measurements of fabricated devices with an aim to employ these in microwave quantum communication & sensing experiments.
suitable as
  • Master’s Thesis Applied and Engineering Physics
Supervisor: Rudolf Gross
Fabrication of low-loss Josephson parametric devices
Superconducting Josephson devices represent one of the leading hardware platforms of modern quantum information processing. In particular, these devices often employ nonlinear parametric effects for tunable coupling schemes or quantum-limited amplification. Such effects can be also used in a multitude of quantum communication & sensing protocols. In this context, a particular challenge arises due to the fundamental requirement for minimizing losses in superconducting systems in order to preserve the fragile quantum nature of related microwave states. To this end, one needs to develop advanced routines for fabrication of low-loss Josephson parametric amplifiers & parametric couplers by exploring various surface treatment approaches or studying novel superconducting materials. The low-loss Josephson devices are to be used in our ongoing experiments towards experimental investigation of particular novel concepts, such as the quantum radar or remote entanglement distribution protocols. This master thesis will involve designing superconducting parametric circuits, cleanroom fabrication, and characterization measurements of fabricated devices with an aim to employ these in microwave quantum communication & sensing experiments.
suitable as
  • Master’s Thesis Quantum Science & Technology
Supervisor: Rudolf Gross
Hybrid quantum teleportation
Microwave quantum communication is a novel field of science and technology, where one exploits quantum properties of propagating microwave signals to achieve quantum advantage in various communication scenarios. Here, a particularly important protocol is quantum teleportation, where one bypasses fundamental limitations on fidelity of transferred quantum states by exploiting shared entanglement. In this context, an open challenge is teleportation of the most exotic, non-Gaussian, quantum states, such as Fock or Schrödinger cat states, with the help of Gaussian entangled states. In theory, this problem can be addressed by using non-deterministic approaches or incorporating non-Gaussian operations in the teleportation protocol. This master thesis will focus on a theory analysis & numerical simulation of quantum microwave teleportation of non-Gaussian quantum states. Later stages of this master project may include experimental investigation of proof-of-principle hybrid quantum teleportation protocols based on superconducting quantum circuits in the cryogenic environment.
suitable as
  • Master’s Thesis Applied and Engineering Physics
Supervisor: Rudolf Gross
Hybrid quantum teleportation
Microwave quantum communication is a novel field of science and technology, where one exploits quantum properties of propagating microwave signals to achieve quantum advantage in various communication scenarios. Here, a particularly important protocol is quantum teleportation, where one bypasses fundamental limitations on fidelity of transferred quantum states by exploiting shared entanglement. In this context, an open challenge is teleportation of the most exotic, non-Gaussian, quantum states, such as Fock or Schrödinger cat states, with the help of Gaussian entangled states. In theory, this problem can be addressed by using non-deterministic approaches or incorporating non-Gaussian operations in the teleportation protocol. This master thesis will focus on a theory analysis & numerical simulation of quantum microwave teleportation of non-Gaussian quantum states. Later stages of this master project may include experimental investigation of proof-of-principle hybrid quantum teleportation protocols based on superconducting quantum circuits in the cryogenic environment.
suitable as
  • Master’s Thesis Quantum Science & Technology
Supervisor: Rudolf Gross
Improving qubit coherence times by surface engineering
Characterization of surfaces is currently a hot topic for the fabrication of superconducting quantum processors. One way to determine surface properties is the measurement of the contact angle of a deionized water droplet on the surface of differently fabricated chips. For this purpose a measurement setup will be built within this thesis. Afterwards the images will be analyzed using a software called "ImageJ" to extract the contact angle between the chipsurface and the droplet. To compare the results from contact angle measurements to qubit performance, qubit chips will be fabricated and measured at cryogenic temperatures.
suitable as
  • Bachelor’s Thesis Physics
Supervisor: Stefan Filipp
Josephson Ring Modulator Coupler Measurement
Adiabatic Quantum Computation aims at finding the solution for optimization problems by adiabatic Hamiltonian evolution. Physically, the problems are encoded in the so-called Ising Hamiltonian and the task is to find the state of lowest energy, the ground state. As can be seen in the Ising Hamiltonian, all spins have to interact with all other spins to be able to deal with general optimization problems. In practice, achieving this all-to-all connectivity is a hard task. A particularly promising approach is the so-called Lechner-Hauke-Zoller architecture, which we want to implement with superconducting circuits. There, one of the fundamental building block is a Josephson ring modulator coupler featuring the strong ZZ interaction. Your task will be the experimental characterization of the JRM coupler. You will analyze the ZZ interaction strength in the on-state and the parasitic cross-talk between the qubits in the off-state of the coupler. Ultimately, you will realize a simple quantum annealing protocol.
suitable as
  • Master’s Thesis Quantum Science & Technology
Supervisor: Rudolf Gross
Josephson Ring Modulator Coupler Measurement
Adiabatic Quantum Computation aims at finding the solution for optimization problems by adiabatic Hamiltonian evolution. Physically, the problems are encoded in the so-called Ising Hamiltonian and the task is to find the state of lowest energy, the ground state. As can be seen in the Ising Hamiltonian, all spins have to interact with all other spins to be able to deal with general optimization problems. In practice, achieving this all-to-all connectivity is a hard task. A particularly promising approach is the so-called Lechner-Hauke-Zoller architecture, which we want to implement with superconducting circuits. There, one of the fundamental building block is a Josephson ring modulator coupler featuring the strong ZZ interaction. Your task will be the experimental characterization of the JRM coupler. You will analyze the ZZ interaction strength in the on-state and the parasitic cross-talk between the qubits in the off-state of the coupler. Ultimately, you will realize a simple quantum annealing protocol.
suitable as
  • Master’s Thesis Condensed Matter Physics
Supervisor: Rudolf Gross
Microwave cryptography with propagating quantum tokens
Quantum cryptography based on continuous-variables is a rapidly growing field of fundamental and applied research. It deals with various topics regarding fundamental limits on data communication & security. In particular, the microwave branch of quantum cryptography demonstrates a large potential for near term applications due to its natural frequency compatibility with the upcoming 5G and future 6G networks. In this context, we plan to investigate microwave photonic states, quantum tokens, which can be used for unconditionally secure storage and transfer of classical information. This security properties are provided by a peculiar combination of the quantum no-cloning theorem and vacuum squeezing phenomenon. The latter effect can be routinely achieved in the microwave regime with superconducting Josephson parametric amplifiers, which we plan to use for experimental generation & investigation of quantum token states. This master thesis will focus on developing numerical & experimental tools for the ongoing microwave quantum cryptography experiments. This includes programming various elements of FPGA data processing routines, performing cryogenic measurements with propagating microwaves, and analyzing measurement data for quantifying quantum correlations & unconditional security in propagating quantum token states.
suitable as
  • Master’s Thesis Quantum Science & Technology
Supervisor: Rudolf Gross
Microwave cryptography with propagating quantum tokens
Quantum cryptography based on continuous-variables is a rapidly growing field of fundamental and applied research. It deals with various topics regarding fundamental limits on data communication & security. In particular, the microwave branch of quantum cryptography demonstrates a large potential for near term applications due to its natural frequency compatibility with the upcoming 5G and future 6G networks. In this context, we plan to investigate microwave photonic states, quantum tokens, which can be used for unconditionally secure storage and transfer of classical information. This security properties are provided by a peculiar combination of the quantum no-cloning theorem and vacuum squeezing phenomenon. The latter effect can be routinely achieved in the microwave regime with superconducting Josephson parametric amplifiers, which we plan to use for experimental generation & investigation of quantum token states. This master thesis will focus on developing numerical & experimental tools for the ongoing microwave quantum cryptography experiments. This includes programming various elements of FPGA data processing routines, performing cryogenic measurements with propagating microwaves, and analyzing measurement data for quantifying quantum correlations & unconditional security in propagating quantum token states.
suitable as
  • Master’s Thesis Applied and Engineering Physics
Supervisor: Rudolf Gross
Observation of quantum switching in driven-dissipative superconducting oscillators
Classical nonlinear systems are known to exhibit metastable behaviour, where spontaneous transitions may take place. These transitions are often associated with spontaneous symmetry breaking and can be viewed as classical phase transitions. However, recent developments in quantum theory of driven-dissipative nonlinear resonators reveal that the underlying switching processes may be of purely quantum nature. This can be experimentally observed during the transient dynamics in nonlinear superconducting resonators. An immediate goal of this master project is to experimentally study switching dynamics in driven Josephson parametric amplifiers (JPAs) and observe quantum features, such as vacuum squeezing and Wigner function negativity, in the associated transient resonator states. The far-reaching goals of this research are related to fundamental investigation of quantum phase transitions in novel driven-dissipative superconducting systems, such as quantum metamaterials. In the framework of this project, the student will experimentally employ existing JPA devices as both the driven-dissipative system and quantum preamplifiers. The latter will be the key for efficient observation and quantum tomography of the transient JPA dynamics. More specifically, the tasks of the master student will consist of the FPGA programming, construction of an experimental set-up in a dilution refrigerator, cryogenic microwave measurements, and data analysis in collaboration with external theory partners. This project will be an important integral part of our various activities on quantum microwave communication, where JPAs are employed as the key building blocks. These activities are supported within the framework of the MCQST cluster, QMiCS project (EU Quantum Flagship), QuaMToMe project (BMBF, "Grand Challenge der Quantenkommunikation"), and will also have a significant overlap with the QuaRaTe project (BMBF) on quantum sensing.
suitable as
  • Master’s Thesis Applied and Engineering Physics
Supervisor: Rudolf Gross
Observation of quantum switching in driven-dissipative superconducting oscillators
Classical nonlinear systems are known to exhibit metastable behaviour, where spontaneous transitions may take place. These transitions are often associated with spontaneous symmetry breaking and can be viewed as classical phase transitions. However, recent developments in quantum theory of driven-dissipative nonlinear resonators reveal that the underlying switching processes may be of purely quantum nature. This can be experimentally observed during the transient dynamics in nonlinear superconducting resonators. An immediate goal of this master project is to experimentally study switching dynamics in driven Josephson parametric amplifiers (JPAs) and observe quantum features, such as vacuum squeezing and Wigner function negativity, in the associated transient resonator states. The far-reaching goals of this research are related to fundamental investigation of quantum phase transitions in novel driven-dissipative superconducting systems, such as quantum metamaterials. In the framework of this project, the student will experimentally employ existing JPA devices as both the driven-dissipative system and quantum preamplifiers. The latter will be the key for efficient observation and quantum tomography of the transient JPA dynamics. More specifically, the tasks of the master student will consist of the FPGA programming, construction of an experimental set-up in a dilution refrigerator, cryogenic microwave measurements, and data analysis in collaboration with external theory partners. This project will be an important integral part of our various activities on quantum microwave communication, where JPAs are employed as the key building blocks. These activities are supported within the framework of the MCQST cluster, QMiCS project (EU Quantum Flagship), QuaMToMe project (BMBF, "Grand Challenge der Quantenkommunikation"), and will also have a significant overlap with the QuaRaTe project (BMBF) on quantum sensing.
suitable as
  • Master’s Thesis Quantum Science & Technology
Supervisor: Rudolf Gross
Remote entanglement of superconducting qubits
Quantum computing represents a promising information processing paradigm exploiting quantum properties, such as superposition and entanglement. The latter entity is crucial for achieving quantum advantage in scalable quantum information processing with distributed quantum computers, including those built with superconducting qubits. Here, an important task is to study how quantum entanglement can be distributed between remote superconducting qubits. To this end, we plan to exploit propagating two-mode squeezed states as a carrier of quantum entanglement. We intend to analyze their interactions with remote superconducting quantum bits in theory & verify our findings in experiments. This master thesis will first focus on theory & numerical simulations of remote entanglement of superconducting qubits with propagating squeezed light. Later project stages may also include cryogenic experiments with superconducting transmon qubits & Josephson parametric amplifiers towards verifying novel concepts of remote entanglement.
suitable as
  • Master’s Thesis Quantum Science & Technology
Supervisor: Rudolf Gross
Remote entanglement of superconducting qubits
Quantum computing represents a promising information processing paradigm exploiting quantum properties, such as superposition and entanglement. The latter entity is crucial for achieving quantum advantage in scalable quantum information processing with distributed quantum computers, including those built with superconducting qubits. Here, an important task is to study how quantum entanglement can be distributed between remote superconducting qubits. To this end, we plan to exploit propagating two-mode squeezed states as a carrier of quantum entanglement. We intend to analyze their interactions with remote superconducting quantum bits in theory & verify our findings in experiments. This master thesis will first focus on theory & numerical simulations of remote entanglement of superconducting qubits with propagating squeezed light. Later project stages may also include cryogenic experiments with superconducting transmon qubits & Josephson parametric amplifiers towards verifying novel concepts of remote entanglement.
suitable as
  • Master’s Thesis Applied and Engineering Physics
Supervisor: Rudolf Gross
Simulation and comparison of non-planar qubit architectures
Scalable designs of superconducting qubits are essential for the creation of large-scale multi-qubit processors used in quantum computers. Superconducting transmon qubits are described by their characteristic capacitance and the critical current of their Josephson-Junction. The capacitance of these qubits orginates from the geometry of the metal islands of the qubit on the chip surface. To accomodate for a large number of qubits and their respective control and readout lines new 3D integration methods have been developed over the last years, extending the superconducting structures beyond a single chip plane. In this work a number of these architectures will be simulated. The focus of this Bachelor thesis lies in the accurate simulation of these designs ranging over different orders of magnitude in size and the extraction of system paramerters from FEM solutions.
suitable as
  • Bachelor’s Thesis Physics
Supervisor: Stefan Filipp

Current and Finished Theses in the Group

Advanced calibration of superconducting qubits
Abschlussarbeit im Masterstudiengang Quantum Science & Technology
Themensteller(in): Stefan Filipp
Generating small magnetic fields inside an open-end magnetic shielding with a superconducting solenoid magnet
Abschlussarbeit im Masterstudiengang Physik (Physik der kondensierten Materie)
Themensteller(in): Rudolf Gross
Microwave Manipulation of Magnon Transport
Abschlussarbeit im Masterstudiengang Physik (Physik der kondensierten Materie)
Themensteller(in): Rudolf Gross
Non-reciprocal devices
Abschlussarbeit im Masterstudiengang Physik (Physik der kondensierten Materie)
Themensteller(in): Rudolf Gross
Superconducting Microwave Resonators for Spin Based Quantum Memories
Abschlussarbeit im Masterstudiengang Physics (Applied and Engineering Physics)
Themensteller(in): Hans-Gregor Hübl
Thermal history dependent electronic properties of κ-(BEDT-TTF)2-X near the Mott-metal-insulator transition
Abschlussarbeit im Masterstudiengang Physik (Physik der kondensierten Materie)
Themensteller(in): Rudolf Gross
Growth optimization of ferromagnetic gadolinium nitride (GdN) thin films for spintronics with magnetic isolators
Abschlussarbeit im Masterstudiengang Physik (Physik der kondensierten Materie)
Themensteller(in): Rudolf Gross
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