The frontier of ultrafast optics and electronics has reached a new milestone with recent advancements in attosecond-scale light-driven current generation. Researchers have unveiled a novel graphene-silicon-graphene (Gr-Si-Gr) phototransistor that enables control over electron movement at speeds reaching 630 attoseconds, equivalent to 1.6 petahertz. This breakthrough positions attosecond optoelectronics as a viable technology for next-generation ultrafast quantum devices.

Ultrafast Light Tools: Capturing Electron Dynamics 

The ability to manipulate ultrashort light pulses has revolutionized the study of electron dynamics. High-harmonic generation in solids, coupled with the emergence of attosecond XUV pulses, has allowed scientists to probe electron interactions in condensed matter. More recently, attomicroscopy has emerged as a tool to visualize bound electron behavior at the nanoscale. Now, the focus is shifting toward actively controlling electron movement using tailored laser waveforms—an approach crucial for designing ultrafast optical switches and high-speed electronic devices.

Image: Ultrafast switching of currents in graphene-based devices. From Sennary et al, Nature Comm. 16, 4335 (2025). Creative Commons 4.0 license.

The Role of Graphene in Light-Induced Currents 

Graphene, with its exceptional conductivity and optical properties, has been central to exploring light-induced currents (LIC). Previously, researchers demonstrated the generation of LIC based on photoexcitation of charge carriers in graphene. This LIC stems from two distinct components: the ultrafast instantaneous field-induced current (IE), generated by virtual carriers temporarily driven by the light field, and the photo-induced current (Ip), resulting from real carrier excitation and relaxation over picoseconds. However, measuring IE directly has remained elusive—until now.

Attosecond Current Switching in a Graphene-Silicon Phototransistor 

For the first time, scientists have achieved direct access to IE by leveraging a graphene-silicon junction. In their newly designed phototransistor, current flow is controlled via quantum tunneling, allowing real-time monitoring of IE. The device exhibits periodic modulation of the ultrafast current synchronized with the light field waveform. This capability enables switching between ON and OFF states with unprecedented speed—attosecond-scale resolution. The research was recently published in the journal Nature Communications.

Beyond ultrafast switching, the researchers enhanced phototransistor conductivity by increasing laser intensity. Moreover, they integrated externally applied DC current with LIC to demonstrate functional logic operations within the device. Most significantly, the entire experiment was conducted under standard ambient conditions, highlighting the real-world applicability of attosecond-driven quantum optoelectronics.

Such precise ultrafast control of photocurrents in graphene would not be possible without graphene of an exceptionally high quality. The research used Graphenea’s mGFET and Graphenea card products.

Future Prospects: Lightwave Electronics and Quantum Technologies 

This advancement propels attosecond science toward practical implementations, bridging the gap between fundamental physics and engineered technologies. With light-controllable quantum tunneling demonstrated in graphene-based devices, prospects for ultrafast optical computing and quantum communication are on the horizon. As research in ultrafast optoelectronics progresses, attosecond lightwave technology may soon redefine the speed limits of modern electronics.