Real-space coherent manipulation of electrons in a single tunnel junction by single-cycle terahertz electric fields

Abstract

Carrier-envelope-phase-controlled single-cycle terahertz pulses can induce coherent electron tunnelling either from a Pt/Ir nanotip to a graphite sample or vice versa. The pulses enable ultrafast nonlinear manipulation of electrons at the atomic scale. The ultrafast coherent manipulation of electrons using waveform-controlled laser pulses1,2,3,4,5,6,7,8,9 is a key issue in the development of modern electronics10,11. Developing such an approach for a tunnel junction will provide a new platform for governing ultrafast currents on an even smaller scale, which will be indispensable for the advancement of next-generation quantum nanocircuits12,13,14,15 and plasmonic devices16,17,18. Here, we demonstrate that carrier-envelope-phase-controlled single-cycle terahertz electric fields can coherently drive electron tunnelling either from a nanotip to a sample or vice versa. Spatially confined electric fields of more than 10 V nm–1 strongly modulate the potential barrier at a nanogap in a scanning tunnelling microscope (STM) on the subpicosecond timescale and can steer a large number of electrons in an extremely nonlinear regime, which is not possible using a conventional STM. Our results are expected to pave the way for the future development of nanoscale science and technologies.