Real-time tracking of coherent oscillations of electrons in a nanodevice by photo-assisted tunnelling

Yang Luo; Frank Neubrech; Alberto Martin-Jimenez; Na Liu; Klaus Kern; Manish Garg

doi:10.1038/s41467-024-45564-w

Real-time tracking of coherent oscillations of electrons in a nanodevice by photo-assisted tunnelling

Nat Commun. 2024 Feb 13;15(1):1316. doi: 10.1038/s41467-024-45564-w.

Authors

Yang Luo¹, Frank Neubrech^{1

2}, Alberto Martin-Jimenez¹, Na Liu^{1

2}, Klaus Kern^{1

3}, Manish Garg⁴

Affiliations

¹ Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569, Stuttgart, Germany.
² 2nd Physics Institute, University of Stuttgart, Pfaffenwaldring 57, 70569, Stuttgart, Germany.
³ Institut de Physique, Ecole Polytechnique Fédérale de Lausanne, 1015, Lausanne, Switzerland.
⁴ Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569, Stuttgart, Germany. mgarg@fkf.mpg.de.

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 T₂ decay time of nearly 8 femtoseconds. The contributions of linear and nonlinear electron oscillations in the generated tunnelling currents were precisely determined. A phase control of electron oscillations in the nanodevice is illustrated. Functioning in ambient conditions, the excitation, phase control, and read-out of coherent electron oscillations pave the way toward on-chip light-wave electronics in quantum nanodevices.