In search of lost time: attosecond physics, petahertz optoelectronics, and quantum speed limit

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.