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Interfacing spin waves with superconducting quantum circuits for single magnon creation and detection

Periodic Reporting for period 3 - QuantumMagnonics (Interfacing spin waves with superconducting quantum circuits for single magnon creation and detection)

Reporting period: 2018-01-01 to 2019-06-30

The proposed project will experimentally interface ferromagnets with superconducting quantum circuits to study dynamics within the magnet. To this end, magnonic elements made up by thin, structured magnetic films will be strongly coupled to the qubit. Exploring spin wave dynamics in thin films by coupling to a superconducting qubit complements conventional measurement techniques based on photon, electron or neutron scattering methods, which require highly populated excitations. The project connects to and extends research objects of ground-breaking nature to open up new horizons for quantum, magnon and spin electronics. Magnetic material physics is enhanced by new research concepts such as quantum resolved spectroscopy and coherence measurements on intrinsic dynamic states.
Overall objectives are: i) Ferromagnetic resonator coupled to transmission line: Spin wave resonance at few magnon levels, ii) Noise spectrum analyzation of ferromagnet: Spectroscopy of spin processes, iii) Ferromagnetic resonator coupled to qubit: Creation and detection of single magnons, iv) Magnetic noise spectroscopy with qubit: Probing low- and high-frequency

Ultimately, this research addresses new paradigms of quantum nanoelectronics for the benefit of society.
Since starting the research project the group has grown substantially. The major investment, a dilution refrigerator, has been delivered after approx. 13 months due to delay on the manufacturer side. The electronic measurement setups have been ordered and delivered before. Setting up the measurement has required to hire several students and postdocs for limited time to use their expertise in cryogenics and high frequency electronics. By month 18 the setup is fully operational, and we are expecting the first measurements in the next weeks. The delays caused by the late delivery were compensated by using other setups in the group, and focusing on numerical analysis and improving measurement software.
We have been designing, fabricating and measuring superconducting resonators and qubits as well as spin waves in ferromagnets. These activities have lead to finished several BA and MA theses projects, and have been presented at national and international conferences. We have been organizing one workshop and one conference in 2016, and giving several interviews to the press.
We will measure, generate and manipulate spin excitations in ferromagnetics by coherent coupling to a superconducting ferromagnet. Using the qubit as noise spectrometer we will determine fluctuations in the spin systems over large order of frequencies.
This project connects to and extends research objects of ground-breaking nature to open up new horizons for quantum, magnon and spin electronics. Magnetic material physics is enhanced by new research concepts suchas quantum resolved spectroscopy and coherence measurements of dynamic states using qubits as detectors. The potential impact of interfacing spin waves with superconducting circuits is suggested by the history of Josephson junctions, qubits and thin film magnetism. Ultimately, this research addresses new paradigms of quantum nanoelectronics for the benefit of society