Engineering sub-Poissonian squeezed magnons by dissipative coupling in giant-atom-coupled waveguide magnonics
Phys. Rev. A 113, 053726 – Published 27 May, 2026
DOI: https://doi.org/10.1103/tnzb-1r5f
Abstract
Quantum squeezing and sub-Poissonian statistics, as independent effects of different orders, reflect nonclassicality through reduced quantum noise of the quadrature components and narrowed number distribution, respectively. In some scenarios, however, these two effects are mutually exclusive. Recent advancements in the realm of the chip-embedded waveguide quantum electrodynamics enable experimental achievements of the giant spin ensemble (GSE) and the giant atom (GA) by coupling a millimeter-sized ferromagnetic yttrium-iron-garnet (YIG) sphere and a transmon-type superconducting qubit to the meandering waveguide at two well-separated points. Here, we propose a win-win scheme to simultaneously generate the optimal quadrature squeezing and the pronounced sub-Poissonian magnon-number statistics with high brightness, owing to the non-Hermitian anharmonicity of the energy levels based on the dissipative coupling within the GSE-GA waveguide system. Besides, the presence of the individual decay rates relaxes the range of the weak-driving condition, which is conducive to improving the brightness and the amount of the magnon squeezing. Physically, we find a direct correlation between the two-level-GA coherence (closely related to the single-magnon excitation processes) and the magnon squeezing (corresponding to spin noise reduction below the vacuum level) as well as the sub-Poissonian magnon-number statistics (corresponding to antibunching). More importantly, our approach is not only robust against the external damping rates and the driving detunings, but also requires neither complex design nor pump modulation, thus facilitating the practical implementation. With realistic experimental parameters, the analytical calculations match very well with the numerical simulations. This study provides insights for engineering versatile nonclassical magnon sources at microwave wavelengths through macroscopic YIG spin systems, integrating two key properties that hold potential to underpin the complex tasks in precision metrology and quantum communication.
