Modern optical physics provides means to detect and resolve ultrafast processes on a time scale of tens of attoseconds. The physical interpretation of such measurements, however, remains the focus of heated debate. In its conceptual dimension, this debate reflects fundamental difficulties in defining time in quantum mechanics. En route toward resolving this difficulty, we are led to extend universal uncertainty relations to ultrafast light–matter interactions. Such a generalized uncertainty sets a lower bound on the response time inherent in attosecond electronic dynamics driven by ultrashort laser pulses, dictating a speed limit for next-generation photonic information systems — systems of petahertz optoelectronics.

现代光学物理学提供了在几十阿秒的时间尺度上检测和解决超快过程的方法。然而，对此类测量的物理解释仍然是激烈争论的焦点。在其概念维度上，这场辩论反映了在量子力学中定义时间的根本困难。在解决这个困难的过程中，我们被引导将普遍不确定性关系扩展到超快光-物质相互作用。这种广义的不确定性为由超短激光脉冲驱动的阿秒电子动力学固有的响应时间设定了下限，决定了下一代光子信息系统——太赫兹光电子系统的速度限制。