Tohoku University Achieves Rabi Splitting While Preserving System Symmetry

Researchers at Tohoku University, led by Assistant Professor Aakanksha Sud and Professor Shigemi Mizukami, along with collaborators from JAEA and UCL, have demonstrated Rabi-like splitting—a phenomenon crucial for advancing quantum information processing—while preserving system symmetry. Published in Physical Review Letters on June 20, 2025, the study details how nonlinear coupling, induced by radio-frequency currents in an artificial magnet, facilitated energy exchange between magnon modes exhibiting both ferromagnetic and antiferromagnetic properties. This achievement departs from conventional methods requiring symmetry-breaking and contributes to a deeper understanding of nonlinear dynamics, potentially informing future high-speed signal processing devices.

Preserving Symmetry in Quantum Coupling

The research demonstrates that Rabi-like splitting can be achieved through nonlinear coupling while preserving the symmetries of the investigated system, a departure from established principles typically requiring a symmetry-breaking element. This finding broadens the scope for understanding nonlinear dynamics and coupling phenomena within artificial control mechanisms, offering potential insights into advanced magnetic materials. The system under investigation features two spatially uniform magnon modes – collective excitations of spin waves – exhibiting distinct ferromagnetic and antiferromagnetic behaviours.

Nonlinear coupling was achieved through the application of large radio-frequency currents to an artificial magnet, facilitating controlled manipulation of energy exchange between the magnon modes. This technique enabled the observation of Rabi-like splitting without disrupting the system’s inherent symmetry, as confirmed by both experimental and theoretical studies. The research team’s findings contribute to a deeper understanding of nonlinear magnon coupling and its potential applications in manipulating magnetic excitations.

The study, published in Physical Review Letters on June 20, 2025, details the methodology and results of this investigation into electrically controlled nonlinear magnon-magnon coupling in a synthetic antiferromagnet. The authors are A. Sud, K. Yamamoto, S. Iihama, K. Ishibashi, S. Fukami, H. Kurebayashi, and S. Mizukami, and the research involved collaborative efforts from multiple institutions including Tohoku University and the Japan Atomic Energy Agency (JAEA). The team intends to extend this work by applying the approach to devices designed for high-speed signal processing.

Nonlinear Magnon Coupling and Rabi Splitting

The research details electrically controlled nonlinear magnon-magnon coupling within a synthetic antiferromagnet, achieved through the application of large radio-frequency currents to an artificial magnet. This technique facilitates controlled manipulation of energy exchange between the two spatially uniform magnon modes, one exhibiting ferromagnetic alignment and the other displaying antiferromagnetic properties. Although these modes can possess identical frequencies under specific conditions, such as the application of an external magnetic field, the observed Rabi-like splitting occurred while maintaining the symmetry of the system.

The findings were published in Physical Review Letters on June 20, 2025, authored by A. Sud, K. Yamamoto, S. Iihama, K. Ishibashi, S. Fukami, H. Kurebayashi, and S. Mizukami. The research involved collaborative efforts from multiple institutions, including Tohoku University and the Japan Atomic Energy Agency (JAEA). The research team intends to extend this work by applying the approach to devices designed for high-speed signal processing.

Implications for Signal Processing

The research team intends to extend this work by applying the approach to devices designed for high-speed signal processing, building upon the demonstrated control of energy exchange between magnon modes. This application suggests a potential pathway for manipulating magnetic excitations within signal processing architectures.

The study details electrically controlled nonlinear magnon-magnon coupling in a synthetic antiferromagnet, as reported in Physical Review Letters on June 20, 2025, authored by A. Sud, K. Yamamoto, S. Iihama, K. Ishibashi, S. Fukami, H. Kurebayashi, and S. Mizukami. The collaborative effort involved WPI Advanced Institute for Materials Research (AIMR), the Frontier Research Institute for Interdisciplinary Sciences (FRIS), the Research Institute of Electrical Communication (RIEC), the Center for Science and Innovation in Spintronics (CSIS), and the Graduate School of Engineering at Tohoku University, alongside contributions from the Japan Atomic Energy Agency (JAEA) and University College London (UCL).