【 Press release】 In-Situ Tailoring of Single-Cycle THz Near Field in a Tunnel Junction


Jun Takeda, Yokohama National University

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 this study, we demonstrate that desirable phase-controlled near fields can be produced in a tunnel junction via terahertz scanning tunneling microscopy (THz-STM) with a broadband THz phase shifter. Measurements of the phase-resolved sub-cycle electron tunneling dynamics revealed an unexpected large carrier-envelope phase shift between far-field and near-field single-cycle THz waveforms, which 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 timescale. 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.

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Katsumasa Yoshioka, Ikufumi Katayama, Yusuke Arashida, Atsuhiko Ban, Yoichi Kawada, Kuniaki Konishi, Hironori Takahashi, and Jun Takeda, Nano Letters 18, 5198-5204 (2018). DOI:10.1021/acs.nanolett.8b02161