A key element of optical spectroscopy is the link between observable selection rules and the underlying symmetries of an investigated physical system. Typically, selection rules directly relate to the sample properties probed by light, yielding information on crystalline structure or chirality, for example. Considering light-matter coupling more broadly may extend the scope of detectable symmetries, to also include those directly arising from the interaction. In this letter, we experimentally demonstrate an emerging class of symmetries in the electromagnetic field emitted by a strongly driven atomic system. Specifically, generating high-harmonic radiation with attosecond-controlled two-color fields, we find different sets of allowed and forbidden harmonic orders. Generalizing symmetry considerations of circularly polarized high-harmonic generation, we interpret these selection rules as a complete triad of dynamical symmetries. We expect such emergent symmetries also for multi-at...

中文翻译：

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阿秒碰撞控制揭示高谐波产生中的动力对称三重轴

光谱学的关键要素是可观察的选择规则与所研究的物理系统的基本对称性之间的联系。通常，选择规则直接与光探测的样品特性有关，例如，产生有关晶体结构或手性的信息。更广泛地考虑光-质耦合可以扩展可检测对称性的范围，也包括直接从相互作用中产生的对称性。在这封信中，我们通过实验证明了强力驱动的原子系统发出的电磁场中新兴的一类对称性。具体来说，在产生具有阿秒控制的双色场的高次谐波辐射时，我们发现了不同的允许和禁止谐波阶数集。归纳出圆极化高谐波产生的对称性考虑，我们将这些选择规则解释为动力学对称的完整三元组。我们希望这种多出现的对称性也适用于多...