Researchers at Te Whai Ao — Dodd-Walls Centre for photonic and quantum technologies and the University of Otago, in collaboration with the Vienna University of Technology, have published a new study in Nature Physics. The paper, titled “Coherent control of magnon–polaritons using an exceptional point,” introduces a new method for controlling hybrid systems where energy loss is used as a tool for system control.
The team, led by Dr. Nicholas Lambert, studied a cavity magnonic system in which the excitations of a magnetic material are coupled to photons at microwave frequencies, forming hybrid particles called magnon–polaritons. By dynamically encircling an exceptional point, a mathematical singularity that emerges from a specific gain–loss imbalance, the researchers demonstrated population transfer between coupled magnon–polariton modes. They also showed that driving the system directly through an exceptional point allows it to be prepared in an equal superposition of eigenmodes.
This form of coherent control is positioned as a new tool to prepare a quantum state, which is a key component for quantum computing and sensing applications. The novel platform offers a way to manipulate hybridised states in a variety of systems, and cavity magnon-polaritons have also received attention for potential applications in quantum networks. The next step for the researchers is to extend their techniques to the quantum regime, with the goal of applying them to quantum technologies.
Read the full announcement here and the paper in Nature Physics here.
August 24, 2025
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