Cavity Magnomechanics: Dynamical Backaction

• Author / Creator

  Potts, Clinton

• Magnetic spin waves (magnons) are promising building blocks in developing classical and quantum hybrid systems. Magnons can couple to numerous sub-systems, such as microwave and optical photons, superconducting qubits and phonons. However, the parametric interaction between magnons and low-frequency phonons has not been widely studied experimentally. To elucidate this, we examined theoretically and experimentally the interaction between gigahertz magnons and megahertz frequency mechanical modes hosted within small spheres of yttrium iron garnet.We developed a linear theory describing the complete magnomechanical interaction using standard quantum optics techniques. From this analysis, we predicted two dynamical backaction effects: the magnon-spring effect, a shift in the phonon frequency and magnomechanical damping of the phonon mode due to the radiation-pressure-like force imparted by the magnon. We also describe the critical triple-resonance condition, where particular interactions are resonantly enhanced by ensuring the phonon frequency matches the magnon-photon normal-mode splitting. Next, we designed and built a cavity magnomechanical system to test our theoretical predictions. As a result, we observe the magnon-spring effect for the first time and magnomechical damping and anti-damping of the phonon mode. Finally, we moved the experiment onto the baseplate of a dilution refrigerator, where we aim to continue to study the behaviour of magnomechanical systems in cryogenic environments.

• Subjects / Keywords

  • Magnons
  • Optomechanics
  • Magnetism

• Graduation date

  Fall 2022

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/r3-hetx-2r76

• License

  This thesis is made available by the University of Alberta Library with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.