Symmetry Breaking and Strong Persistent Plasma Currents via Resonant Destabilization of Atoms.
Symmetry Breaking and Strong Persistent Plasma Currents via Resonant Destabilization of Atoms.
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DOI：
10.1103/physrevlett.119.243202
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发表时间：
2017-12
影响因子：
8.6
通讯作者：
C. Brée;M. Hofmann;A. Demircan;U. Morgner;O. Kosareva;A. Savel’ev;A. Husakou;M. Ivanov;I. Babus
中科院分区：
文献类型：
--
作者：
C. Brée;M. Hofmann;A. Demircan;U. Morgner;O. Kosareva;A. Savel’ev;A. Husakou;M. Ivanov;I. Babus
在强光场中，原子的电离率可以通过长寿命原子能级（所谓的弗里曼共振）的存在而共振地增强。这个过程在多光子电离状态下最为突出，这意味着电离事件需要许多光周期。然而，在这里，我们表明这些共振可以导致在泵脉冲强度的共振值下快速的亚周期尺度等离子体积累。这种快速的积累会打破电离过程的周期到周期的对称性，从而产生持续的宏观等离子体电流，这些电流在脉冲结束后仍然存在。这反过来又产生了一种不寻常的光谱结构的宽带辐射，形成了一个从太赫兹到可见光的梳状结构。这种辐射包含电离过程中里德堡态的阿秒电子动力学指纹。
The ionization rate of an atom in a strong optical field can be resonantly enhanced by the presence of long-living atomic levels (so-called Freeman resonances). This process is most prominent in the multiphoton ionization regime, meaning that the ionization event takes many optical cycles. Nevertheless, here, we show that these resonances can lead to rapid subcycle-scale plasma buildup at the resonant values of the intensity in the pump pulse. The fast buildup can break the cycle-to-cycle symmetry of the ionization process, resulting in the generation of persistent macroscopic plasma currents which remain after the end of the pulse. This, in turn, gives rise to a broadband radiation of unusual spectral structure, forming a comb from terahertz to visible. This radiation contains fingerprints of the attosecond electron dynamics in Rydberg states during ionization.