发表机构
Chonnam National University; Massachusetts Institute of Technology（全南国立大学; 麻省理工学院）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文建立统一理论框架，利用太赫兹二维相干光谱解锁量子材料带内非线性动力学，并综述其在等离子体激元、声子等研究中的应用。
AI 中文摘要
量子材料承载着丰富的低能集体激发谱——声子、磁振子、等离子体激元、极化激元以及希格斯模式——这些激发从根本上决定了材料的涌现性质，然而当非线性路径重叠或出现非微扰动力学时，传统的线性太赫兹光谱无法探测这些激发。太赫兹二维相干光谱（THz-2DCS）通过相位稳定的高场太赫兹脉冲序列实现，直接解决了这一挑战，它提供相位分辨的多维光谱，能够独特地将相干带内非线性量子动力学与非相干背景区分开来。在此，我们通过使用密度矩阵形式结合光学布洛赫方程，建立了一个统一的理论框架，从中系统地推导出非线性路径，并在布洛赫球上可视化。该框架深入理解了低能非线性动力学，这些动力学根据散射机制表现出均匀或非均匀展宽，从而能够解释微扰区（由磁化率展开描述）和非微扰区中的非线性信号。基于此基础，我们全面综述了THz-2DCS在非线性等离子体激元、声子、磁振子和极化激元研究中的应用。最后，我们展望了未来机遇，包括与光泵浦太赫兹探测平台集成以实现非平衡量子控制。
英文摘要
Quantum materials host a rich spectrum of low-energy collective excitations- phonons, magnons, plasmons, polaritons, and Higgs modes- that fundamentally govern their emergent properties, but remain inaccessible to conventional linear THz spectroscopy when nonlinear pathways overlap or non-perturbative dynamics emerge. Terahertz two-dimensional coherent spectroscopy (THz-2DCS), realized through phase-stable high-field THz pulse sequences, directly resolves this challenge by delivering phase-resolved multidimensional spectra that uniquely disentangle coherent intraband nonlinear quantum dynamics from incoherent backgrounds. Here, we establish a unified theoretical framework by using density-matrix formalism combined with the optical Bloch equations, from which nonlinear pathways are systematically derived and visualized on the Bloch sphere. This framework provides insight into low-energy nonlinear dynamics exhibiting homogeneous or inhomogeneous broadening depending on the scattering mechanism, enabling the interpretation of nonlinear signals in both the perturbative regime, described by a susceptibility expansion, and the non-perturbative regime. Building on this foundation, we comprehensively survey THz-2DCS investigations of nonlinear plasmon, phonon, magnon, and polariton. Finally, we outline future opportunities, including integration with optical-pump THz-probe platforms for nonequilibrium quantum control.
Comments8 pages
