标题： 在超快时间尺度上调谐手性振幅 显示英文标题

标题： Tuning chirality amplitude at ultrafast timescales

摘要： 手性是一种基本的对称性概念，描述离散状态，即左手性、右手性或非手性，并存在于不同的尺度和许多科学领域的类别中。 尽管对称性破缺对于定性描述不同的现象是必不可少的，但对称性无法定量预测可测量的量。 可以连续扭曲一个物体，引入手性振幅的概念，类似于将磁化表示为时间反演对称性破缺的振幅。 考虑到磁化在具有时间反演对称性破缺的涌现现象中的作用，手性振幅直观上是控制与手性相关的涌现现象的关键量。 在这里，我们提出了两种类型的手性晶格畸变，并展示了它们在超快时间尺度上的振幅可调性。 使用圆偏振的共振X射线衍射是一种直接测量晶体手性的成熟技术。 我们在光激发后实时量化了手性振幅的超快变化。 使用太赫兹激发，我们观察到对应于特定声子频率的共振衍射强度的振荡。 这表明产生了额外的不对称性，也可以描述为手性振幅的增强。 我们提出的手性振幅概念及其超快控制可能会导致一种独特的方法，在超快时间尺度上控制由手性引起的涌现现象。 显示英文摘要

摘要： Chirality is a fundamental symmetry concept describing discrete states, i.e., left-handed, right-handed, or achiral, and existing at disparate scales and in many categories of scientific fields. Even though symmetry breaking is indispensable for describing qualitatively distinct phenomena, symmetry cannot quantitatively predict measurable quantities. One can continuously distort an object, introducing the concept of chirality amplitude, similar to representing magnetization as the amplitude of time-reversal symmetry breaking. Considering the role of magnetization in emergent phenomena with time-reversal symmetry breaking, chirality amplitude is intuitively a key quantity for controlling chirality-related emergent phenomena. Here, we propose two types of chiral lattice distortions and demonstrate the tunability of their amplitude in ultrafast timescales. Resonant X-ray diffraction with circular polarization is an established technique to measure crystal chirality directly. We quantify the ultrafast change in chirality amplitude in real time after an optical excitation. Using instead a THz excitation, we observe oscillations in the resonant diffraction intensities corresponding to specific phonon frequencies. This indicates the creation of additional asymmetry, which could also be described as an enhancement in chirality amplitude. Our proposed concept of chirality amplitude and its ultrafast control may lead to a unique approach to control chirality-induced emergent phenomena in ultrafast timescales.