发表机构
Hong Kong Baptist University; Shenzhen Institute for Research and Continuing Education, Hong Kong Baptist University（香港浸会大学; 香港浸会大学深圳研究院）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究分析非厄米晶格在异常亏损条件下的格林函数，发现频域二阶极点导致超洛伦兹线形和损耗复活趋肤效应，时域线性放大因子增强趋肤动力学，为耗散控制宽带异常响应提供理论框架。
AI 中文摘要
异常亏损是一种新发现的宽带非厄米条件，在该条件下，系统的频谱完全由异常点组成，且所有本征向量成对合并。在此，我们通过考虑非厄米晶格的频率和时域格林函数，分析了其在异常亏损处的稳态和时域响应。我们表明，频域格林函数的特征在于整个频谱上出现二阶极点，从而产生宽带二阶超洛伦兹线形、增强的幅度以及每个共振处连续的2π相位移动。这些二阶极点还支撑了对全局耗散的非传统响应，由此我们揭示了缺陷趋肤效应的损耗复活：由于系统在异常亏损处的缺陷性而“缺失”的趋肤模式可以在响应中重新出现。在时域响应中，我们在演化核中识别出一个随时间线性增长的放大因子，该因子可以增强原本会被全局损耗抑制的趋肤效应动力学。放大强度随系统的缺陷程度缩放，并随着子系统之间的频谱失谐而减弱。我们的工作为分析异常亏损的稳态和动态特征建立了理论框架，并为耗散控制的宽带异常响应开辟了新途径。
英文摘要
Exceptional deficiency is a newly discovered broadband non-Hermitian condition, at which the system's spectrum is entirely composed of exceptional points and all eigenvectors pairwise coalesce. Here, we analyze the steady-state and time-domain responses of non-Hermitian lattices at exceptional deficiency by considering their frequency and time-domain Green's functions. We show that the frequency-domain Green's functions are characterized by the emergence of second-order poles across the entire spectrum, producing broadband second-order super-Lorentzian line shapes, enhanced magnitude, and sequential 2pi phase shifts across each resonance. These second-order poles also underpin unconventional responses to global dissipation, by which we uncover a loss-revival of defective skin effect: the skin modes that are "missing" due to the system's defectiveness at exceptional deficiency can re-emerge in the responses. In the time-domain responses, a linear-in-time amplification factor is identified in the evolution kernel, which can enhance skin-effect dynamics that would otherwise be suppressed by global loss. The amplification strength scales with the degree of defectiveness of the system and diminishes upon spectral detuning between subsystems. Our work establishes a theoretical framework for analyzing steady-state and dynamic signatures of exceptional deficiency, and opens new routes for dissipation-controlled broadband exceptional responses.
Journal refAdvanced Sciences, e77721 (2026)
