AI 中文总结
本文研究空间平移对称性失配的时间界面处的波散射，建立多通道时间散射理论并验证，发现对称性失配可实现常规时间界面无法产生的波矢与频率的同时调控。
AI 中文摘要
时间界面通过破缺时间平移对称性实现波的操控，但常规表述通常假设界面两侧的空间平移对称性保持不变。本文研究具有失配空间对称性的周期介质之间的时间界面，发现切换前后介质的倒格矢会进入广义准动量匹配条件，产生倒格矢辅助的波矢转换。随后建立多通道时间散射理论，并在一维和二维弹性晶格中验证，单个入射布洛赫模式可激发多个具有不同波矢和频率的界面后布洛赫模式，这是常规时间界面无法实现的响应。这些结果将对称性失配确立为时间调制周期介质中同时控制波矢和频率的新自由度。
英文摘要
Temporal interfaces enable wave manipulation through broken time-translation symmetry, but conventional formulations generally assume that spatial-translation symmetry is preserved across the interface. Here we consider temporal interfaces between periodic media with mismatched spatial symmetries. It is discovered that the reciprocal-lattice vectors of the pre- and post-switching media enter a generalized quasi-momentum-matching condition, giving rise to reciprocal-lattice-assisted wave-vector conversion. We then develop a multichannel temporal-scattering theory and validate it in one- and two-dimensional elastic lattices. A single incident Bloch mode can thereby excite multiple post-interface Bloch modes with distinct wave vectors and frequencies, a response inaccessible at conventional temporal interfaces. These results establish symmetry mismatch as a new degree of freedom for simultaneous control of wave vector and frequency in time-modulated periodic media.
