Tunable Ultrastrong Magnon-Magnon Coupling and Squeezed States in a Triaxial Van der Waals Antiferromagnet
This research investigates ultrastrong magnon-magnon coupling (USC) in CrPS4, a van der Waals antiferromagnet, between chiral and acoustic/optical modes. The study uses a full quantum model to show how USC generates non-classical squeezed magnon vacuum states. A practical protocol is developed to link these microscopic coupling parameters directly to measurable magnetization fluctuations, allowing the detection of squeezing up to 9.7 dB from thermal noise.