Real-Time Tracking of Coherent Oscillations of Electrons in a Nanodevice by Photo-assisted Tunnelling

TL;DR

This paper demonstrates real-time tracking and control of collective electron oscillations in a nanodevice using photo-assisted tunnelling, enabling insights into ultrafast light-matter interactions at the atomic scale.

Contribution

It introduces a method for real-time measurement and coherent control of electron oscillations in a nanostructure, advancing quantum nanodevice technology.

Findings

Electron oscillations decay time is nearly 10 femtoseconds.

Linear and nonlinear contributions to tunnelling currents are precisely distinguished.

Coherent control of electron oscillations is achieved in ambient conditions.

Abstract

Coherent collective oscillations of electrons excited in metallic nanostructures (localized surface plasmons) can confine incident light to atomic scales and enable strong light-matter interactions, which depend nonlinearly on the local field. Direct sampling of such collective electron oscillations in real-time is crucial to performing petahertz scale optical modulation, control, and readout in a quantum nanodevice. Here, we demonstrate real-time tracking of collective electron oscillations in an Au bowtie nanoantenna, by recording photo-assisted tunnelling currents generated by such oscillations in this quantum nanodevice. The collective electron oscillations show a noninstantaneous response to the driving laser fields with a decay time of nearly 10 femtoseconds. The temporal evolution of nonlinear electron oscillations resulting from the coherent nonlinear optical response of the nanodevice were also traced in real-time. The contributions of linear and nonlinear electron oscillations in the generated tunnelling currents in the nanodevice were precisely determined. A coherent control of electron oscillations in the nanodevice is illustrated directly in the time domain. Functioning in ambient conditions, the excitation, coherent control, and read-out of coherent electron oscillations pave the way toward on-chip light-wave electronics in quantum nanodevices.