发表机构
The University of Hong Kong; HK Institute of Quantum Science and Technology, The University of Hong Kong（香港大学; 香港大学量子科学与技术研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究揭示了时间调制光子介质中存在时间手性，其由演化算子的伪厄米性和伪幺正性约束决定，通过时间-$\boldsymbol{\rm PT}$对称系统验证了调制回路取向可作为控制Floquet波动力学的旋钮。
AI 中文摘要
我们揭示了时间调制光子介质中的时间手性：反转复介电常数所描绘闭合回路的取向，可使Floquet谱保持不变，同时在相同激发下强烈改变定向散射响应。该行为与演化算子的两个对称性约束相关，即伪厄米性和伪幺正性。我们基于散射振幅的复Bogoliubov参数化，证明了时间手性的普遍存在。我们在单谐波时间-$\boldsymbol{\rm PT}$对称系统中阐释了这些发现：在相变时，两种调制回路取向均支持相同的类真空Floquet光子带，但一种取向会抑制反向光子产生，而另一种取向则会诱导强增长，这已通过全波模拟得到证实。我们的研究结果确立了时间手性为时变光子学中的一个独特概念，并将调制回路取向确定为Floquet波动力学的一个控制旋钮。
英文摘要
We reveal temporal chirality in time-modulated photonic media: reversing the orientation of a closed loop traced by the complex permittivity can leave the Floquet spectrum unchanged while strongly modifying the directional scattering response under the same excitation. This behavior is linked to two symmetry constraints on the evolution operator, namely pseudo-Hermiticity and pseudo-unitarity. We prove the general occurrence of temporal chirality based on a complex Bogoliubov parametrization of the scattering amplitudes. We illustrate these findings in a single-harmonic temporal-$\mathcal{PT}$-symmetric system: both modulation-loop orientations support the same vacuum-like Floquet photonic bands at the phase transition, but one suppresses backward photon generation whereas the other induces strong growth, as confirmed by full-wave simulations. Our results establish temporal chirality as a distinct notion in time-varying photonics and identify modulation-loop orientation as a control knob for Floquet wave dynamics.
