Multi-petahertz electronic metrology

Abstract

Investigations using single-cycle intense optical fields to drive electron motion in bulk silicon dioxide show that the light-induced electric currents extend in frequency up to about 8 petahertz. The speed of electronics, and hence of computing, is limited by the frequencies of the electric currents that are used. Light fields can induce and manipulate electric currents at vastly higher frequencies than are achievable in conventional devices, and Eleftherios Goulielmakis and colleagues now extend this approach to reach an even faster regime. They use single-cycle intense optical fields to drive electron motion in the bulk of silicon dioxide and show that the light-induced intraband electric currents extend in frequency up to about eight petahertz. This demonstration of real-time access to the dynamic nonlinear conductivity of silicon dioxide, with the ability to directly probe and control the intraband currents on attosecond timescales, establishes intense light fields as a platform for multi-petahertz coherent electronics and points to new opportunities for fundamental studies of electron dynamics in condensed matter. The frequency of electric currents associated with charge carriers moving in the electronic bands of solids determines the speed limit of electronics and thereby that of information and signal processing1. The use of light fields to drive electrons promises access to vastly higher frequencies than conventionally used, as electric currents can be induced and manipulated on timescales faster than that of the quantum dephasing of charge carriers in solids2. This forms the basis of terahertz (1012 hertz) electronics in artificial superlattices2, and has enabled light-based switches3,4,5 and sampling of currents extending in frequency up to a few hundred terahertz. Here we demonstrate the extension of electronic metrology to the multi-petahertz (1015 hertz) frequency range. We use single-cycle intense optical fields (about one volt per ångström) to drive electron motion in the bulk of silicon dioxide, and then probe its dynamics by using attosecond (10−18 seconds) streaking6,7 to map the time structure of emerging isolated attosecond extreme ultraviolet transients and their optical driver. The data establish a firm link between the emission of the extreme ultraviolet radiation and the light-induced intraband, phase-coherent electric currents that extend in frequency up to about eight petahertz, and enable access to the dynamic nonlinear conductivity of silicon dioxide. Direct probing, confinement and control of the waveform of intraband currents inside solids on attosecond timescales establish a method of realizing multi-petahertz coherent electronics. We expect this technique to enable new ways of exploring the interplay between electron dynamics and the structure of condensed matter on the atomic scale.