title: Spatiotemporal path discontinuities of wavepackets propagating across a meta-atom.
abstract: The realization of phase discontinuities across metasurfaces has led to a new class of reflection and refraction. Here we present theory and experiment on the discontinuous propagation of wavepackets across subwavelength-thickness meta-atoms. Using acoustic waves, we observe the process of wavepackets traversing a meta-atom with abrupt displacements, which appear as path discontinuities on a space-time diagram. We construct a tunable meta-atom from two coupled resonators at ~500 Hz, map the spatiotemporal trajectories of individual sonic pulses, and reveal discontinuities at the meta-atom where the pulses exit at a time ~50 ms ahead or behind their arrivals. Applications include thin acoustic metasurface lenses.
authors.affiliation: Institute of Physics and Applied Physics, Yonsei University, Seoul 120-749, Korea.
authors.forename: Insang
authors.initials: I
authors.lastname: Yoo
authors.affiliation: Institute of Physics and Applied Physics, Yonsei University, Seoul 120-749, Korea.
authors.forename: Chung Kyu
authors.initials: CK
authors.lastname: Han
authors.affiliation: Department of Applied Physics and Department of Bionanotechnology, Hanyang University, Ansan 426-791, Korea.
authors.forename: Dong-Soo
authors.initials: DS
authors.lastname: Shin
authors.affiliation: Department of Physics, Ewha Womans University, Seoul 120-750, Korea.
authors.forename: K J B
authors.initials: KJ
authors.lastname: Lee
authors.affiliation: Department of Physics, Ewha Womans University, Seoul 120-750, Korea.
authors.forename: J W
authors.initials: JW
authors.lastname: Wu
authors.affiliation: Department of Physics, Pusan National University, Busan KR-609-735, Korea.
authors.forename: Han Seb
authors.initials: HS
authors.lastname: Moon
authors.affiliation: Division of Applied Physics, Faculty of Engineering, Hokkaido University, Sapporo 060-8628, Japan.
authors.forename: Oliver B
authors.initials: OB
authors.lastname: Wright
authors.affiliation: Institute of Physics and Applied Physics, Yonsei University, Seoul 120-749, Korea.
authors.forename: Sam H
authors.initials: SH
authors.lastname: Lee
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