Tunable Ultrastrong Magnon-Magnon Coupling and Squeezed States in a Triaxial Van der Waals Antiferromagnet
Abstract
Achieving and quantifying ultrastrong magnon-magnon coupling (USC) remains a key challenge for quantum magnonics. Here, we demonstrate widely tunable USC between chiral (right- and left-handed) and acoustic or optical magnon modes in the van der Waals antiferromagnet CrPS4. Using a full quantum model, we decompose the interaction into three microscopic interaction channels: the co-rotating term g1 (mode hybridization), the counter-rotating term g2 (two-mode squeezing), and, uniquely in the chiral regime, the self-squared term g3 that mediates single-mode squeezing. The normalized coupling ratio reaches g/fg ∼ 0.41, entering the USC regime. Most significantly, we establish a complete protocol linking these USC parameters to a measurable quantum phenomenon: a squeezed magnon vacuum state. Our simulations not only visualize the chirality and polarization evolution of the hybrid modes but also demonstrate how to directly extract quadrature fluctuations and a substantial squeezing factor (up to ∼ 9.7 dB) from thermal noise-driven magnetization dynamics. This work provides a material-specific quantum framework for USC and a practical pathway to detect and exploit non-classical magnon states in low-damping two-dimensional magnets, opening a route toward quantum-enhanced spintronics and hybrid quantum information platforms.
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BibTeX
@misc{xiao2026tunable,
title = {{Tunable Ultrastrong Magnon-Magnon Coupling and Squeezed States in a Triaxial Van der Waals Antiferromagnet}},
author = {Xiao Xiao and Zishuang Li and Zui Tao and Lina Chen and Ping Liu and Shuai Zhang and Haozhe Wang and Yong Pu and Ronghua Liu},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.11859},
eprint = {2610.11859},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.11859},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Tunable Ultrastrong Magnon-Magnon Coupling and Squeezed States in a Triaxial Van der Waals Antiferromagnet
AU - Xiao Xiao
AU - Zishuang Li
AU - Zui Tao
AU - Lina Chen
AU - Ping Liu
AU - Shuai Zhang
AU - Haozhe Wang
AU - Yong Pu
AU - Ronghua Liu
PY - 2026
DA - 2026/10/08
PB - arXiv
DO - 10.48550/arxiv.2610.11859
UR - https://arxiv.org/abs/2610.11859
AB - Achieving and quantifying ultrastrong magnon-magnon coupling (USC) remains a key challenge for quantum magnonics. Here, we demonstrate widely tunable USC between chiral (right- and left-handed) and acoustic or optical magnon modes in the van der Waals antiferromagnet CrPS_4. Using a full quantum model, we decompose the interaction into three microscopic interaction channels: the co-rotating term g_1 (mode hybridization), the counter-rotating term g_2 (two-mode squeezing), and, uniquely in the chiral regime, the self-squared term g_3 that mediates single-mode squeezing. The normalized coupling ratio reaches g/f_g ∼ 0.41, entering the USC regime. Most significantly, we establish a complete protocol linking these USC parameters to a measurable quantum phenomenon: a squeezed magnon vacuum state. Our simulations not only visualize the chirality and polarization evolution of the hybrid modes but also demonstrate how to directly extract quadrature fluctuations and a substantial squeezing factor (up to ∼ 9.7 dB) from thermal noise-driven magnetization dynamics. This work provides a material-specific quantum framework for USC and a practical pathway to detect and exploit non-classical magnon states in low-damping two-dimensional magnets, opening a route toward quantum-enhanced spintronics and hybrid quantum information platforms.
ER -