Title: Terahertz funneling induced tunneling through nanometer and Angstrom-sized gaps

Speaker: Prof. Dai-Sik Kim, Department of Physics and Astronomy, Seoul National University

Abstract: Terahertz waves squeeze themselves into extreme aspect ratio slot antennas. In the middle of a nano slot antennas, the electric field intensity can be a billion times stronger than the incident one. Thereby, at large enough incident field, quantum tunneling of electrons through nanometer and Angstrom sized gaps occur [1-3]. These efforts originated from nearly perfect transmission through terahertz slot antennas with tens of microns of feature size, and together with its nanometer sized counterparts [4-5]. We will discuss our recent results on tunneling through macroscopic rings of quantum barriers. Surface current driven tunneling provides a new paradigm compared with the conventional voltage driven tunneling, being ultrasensitive to the global geometry and symmetry of the planar geometry. We re-introduce lateral geometry into light induced tunneling processes.

[1] Y. M. Bahk et al., “Electromagnetic Saturation of Angstrom-Sized Quantum Barriers at Terahertz Frequencies”, Physical Review Letters 115, 125501(2015) *cover article. [2] Joon-Yeon Kim et al., “Terahertz Quantum Plasmonics of Nanoslot Antennas in Nonlinear Regime”, Nano Letters 15 (10), 6683-6688 (2015). [3] Xiaoshu Chen, H. R. Park et al., “Atomic layer lithography of wafer-scale nanogap arrays for extreme confinement of electromagnetic waves”, Nat. Comm. 4, 2361 (2013). [4] J. W. Lee et al., “Terahertz Electromagnetic Wave Transmission through Random Arrays of Single Rectangular Holes and Slits in Thin Metallic Sheets”, Physical Review Letters 99, 137401 (2007). [5] M. A. Seo et al., “Terahertz field enhancement by a metallic nano slit operating beyond the skin-depth limit”, Nat. Photonics 3, 152 (2009).