A dielectric material’s response to light is microscopically defined by field-cycle-driven motion of electron densities in the restoring forces of the atomic environment. Here we apply single-cycle mid-infrared pulses to drive the nonlinear motion of valence electrons in a heteronuclear crystal with asymmetric structure and report how the macroscopic optical response can be tracked back to the real-space electron dynamics in the symmetry-breaking potential along the chemical bonds. Whether our single-cycle field drives electrons from the less electronegative to the more electronegative element or vice versa controls the appearance of a smooth nonlinear output spectrum or one with even and odd harmonic orders. Crystal angle scans reveal the absolute orientation of the asymmetric bonds. Directional motion of valence charges controlled by a single cycle of light can therefore be used for spectroscopically exploring the binding potential, to understand and design novel materials for nonlinear optics, or to eventually process information at the frequency of light.

中文翻译：

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极性化学键中价电子运动的非对称单周期控制

介电材料对光的响应在微观上由原子密度的恢复力中电子密度的场周期驱动运动定义。在这里，我们应用单周期中红外脉冲来驱动具有非对称结构的异核晶体中价电子的非线性运动，并报告宏观光学响应如何沿对称断裂势沿真实空间电子动力学追溯。化学键。我们的单周期场是将电子从电负性较低的元素驱动到电负性较高的元素，还是反之亦然，这将控制平滑的非线性输出频谱或偶数和奇次谐波阶数的出现。晶体角扫描揭示了不对称键的绝对取向。