AI 中文总结
本文研究广义双模量子拉比模型，揭示相锁定机制是竞争软模不稳定性与可调多临界性的微观起源，建立了相拓扑、集体激发与热力学可观测量的统一联系。
AI 中文摘要
多临界现象在量子多体系统中占据核心地位，但其在光-物质平台中的微观起源仍在很大程度上未被探索。本文研究了具有独立可调旋转波耦合与反旋转波耦合的广义双模量子拉比模型，证明各向异性通过将相锁定复杂超辐射序参量，使具有无隙戈德斯通类模式的母U(1)对称超辐射流形发生分裂；该相锁定机制为类坐标与类动量软模不稳定性、对称相关的两点与四点多临界拓扑的出现，以及对应的热力学响应提供了共同的微观起源。在统一的玻戈留波夫框架内，本文进一步展示了主导软模如何在两个对称相关的不稳定性通道间重新分布，从而决定多临界相结构；所得相边界由集体软模软化确定，且与平均场不稳定性条件完全吻合。本文还证明多临界拓扑直接编码于全量子基态能量及其响应函数中，建立了相拓扑、竞争集体激发与热力学可观测量之间的统一联系。研究结果表明，竞争软模通道是强耦合光-物质系统中可调多临界性的微观起源。
英文摘要
Multicritical phenomena play a central role in quantum many-body systems, yet their microscopic origin in light--matter platforms remains largely unexplored. Here we investigate a generalized two-mode quantum Rabi model with independently tunable rotating- and counter-rotating-wave couplings. We demonstrate that anisotropy lifts the parent U(1)-symmetric superradiant manifold with a gapless Goldstone-like mode by phase locking the complex superradiant order parameter. This phase-locking mechanism provides the common microscopic origin of the coordinate- and momentum-like soft-mode instabilities, the emergence of symmetry-related two- and four-triple-point multicritical topologies, and the corresponding thermodynamic responses. Within a unified Bogoliubov framework, we further show how the dominant soft mode is redistributed between the two symmetry-related instability channels, thereby determining the multicritical phase structure. The resulting phase boundaries are determined by collective soft-mode softening and coincide exactly with the mean-field instability conditions. We further show that the multicritical topology is directly encoded in the full quantum ground-state energy and its response functions, establishing a unified connection between phase topology, competing collective excitations, and thermodynamic observables. Our results identify competing soft-mode channels as the microscopic origin of tunable multicriticality in strongly coupled light--matter systems.
Comments25 pages, 10 figures; submitted to Physical Review A
