Tailoring Single-Cycle Near Field in a Tunnel Junction with Carrier-Envelope Phase-Controlled Terahertz Electric Fields

• Published in: Nano letters Vol. 18; no. 8; pp. 5198 - 5204
• Main Authors: Yoshioka, Katsumasa, Katayama, Ikufumi, Arashida, Yusuke, Ban, Atsuhiko, Kawada, Yoichi, Konishi, Kuniaki, Takahashi, Hironori, Takeda, Jun
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 08-08-2018
• Subjects: THz-STM; ultrasmall; single-cycle near field; light-field-driven process; ultrafast
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/acs.nanolett.8b02161

Light-field-driven processes occurring under conditions far beyond the diffraction limit of the light can be manipulated by harnessing spatiotemporally tunable near fields. A tailor-made carrier envelope phase in a tunnel junction formed between nanogap electrodes allows precisely controlled manipulation of these processes. In particular, the characterization and active control of near fields in a tunnel junction are essential for advancing elaborate manipulation of light-field-driven processes at the atomic-scale. Here, we demonstrate that desirable phase-controlled near fields can be produced in a tunnel junction via terahertz scanning tunneling microscopy (THz-STM) with a phase shifter. Measurements of the phase-resolved subcycle electron tunneling dynamics revealed an unexpected large carrier-envelope phase shift between far-field and near-field single-cycle THz waveforms. The phase shift stems from the wavelength-scale feature of the tip–sample configuration. By using a dual-phase double-pulse scheme, the electron tunneling was coherently manipulated over the femtosecond time scale. Our new prescriptionin situ tailoring of single-cycle THz near fields in a tunnel junctionwill offer unprecedented control of electrons for ultrafast atomic-scale electronics and metrology.