High-order harmonic generation (HHG) in solids was expected to be efficient due to their high density. However, the strict transition laws in crystals restrict the number of HHG channels. Quasicrystals with fractal band structures could solve this problem and produce multichannel HHG emissions, which has been rarely studied. We simulate the Fibonacci quasicrystal (FQ) HHG for the first time and investigate the electron dynamics on the attosecond timescale. Our results reveal that (i) the acceleration theorem is approximately applicable in FQ, which provides us a valuable tool to analyze the electron trajectories. (ii) Fractal bands lead to more excitation channels, analogous to the forbidden nonvertical electron transitions in crystals. (iii) The broken symmetry results in more frequent backscattering of electrons. (iv) Compared with crystals, multichannel HHG in FQ has a higher yield and wider spectral range. Our results pave the way to understand and control the HHG in quasicrystals and shed light on a potential shorter and stronger attosecond light source based on compact solids.

中文翻译：

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从斐波那契准晶体中的分形带产生多通道高阶谐波

由于其高密度，固体中的高次谐波产生 (HHG) 预计是有效的。然而，晶体中严格的跃迁规律限制了 HHG 通道的数量。具有分形带结构的准晶可以解决这个问题并产生多通道 HHG 发射，这很少被研究。我们首次模拟了斐波那契准晶 (FQ) HHG，并研究了阿秒时间尺度上的电子动力学。我们的结果表明 (i) 加速度定理近似适用于 FQ，这为我们分析电子轨迹提供了一个有价值的工具。(ii) 分形带导致更多的激发通道，类似于晶体中禁止的非垂直电子跃迁。(iii) 破坏的对称性导致更频繁的电子背向散射。(iv) 与晶体相比，FQ 中的多通道 HHG 具有更高的产量和更宽的光谱范围。我们的结果为理解和控制准晶体中的 HHG 铺平了道路，并揭示了基于致密固体的潜在的更短、更强的阿秒光源。