Observation of π/2 Modes in an Acoustic Floquet System

Zheyu Cheng, Raditya Weda Bomantara, Haoran Xue, Weiwei Zhu, Jiangbin Gong, Baile Zhang

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


Topological phases of matter have remained an active area of research in the last few decades. Periodic driving is a powerful tool for enriching such exotic phases, leading to various phenomena with no static analogs. One such phenomenon is the emergence of the elusive π/2 modes, i.e., a type of topological boundary state pinned at a quarter of the driving frequency. The latter may lead to the formation of Floquet parafermions in the presence of interaction, which is known to support more computational power than Majorana particles. In this Letter, we experimentally verify the signature of π/2 modes in an acoustic waveguide array, which is designed to simulate a square-root periodically driven Su-Schrieffer-Heeger model. This is accomplished by confirming the 4T-periodicity (T being the driving period) profile of an initial-boundary excitation, which we also show theoretically to be the smoking gun evidence of π/2 modes. Our findings are expected to motivate further studies of π/2 modes in quantum systems for potential technological applications.

Original languageEnglish
Article number254301
JournalPhysical Review Letters
Issue number25
StatePublished - 16 Dec 2022

Bibliographical note

Funding Information:
Z. C., H. X., and B. Z. are supported by the Singapore Ministry of Education Academic Research Fund Tier 2 Grant No. MOE2019-T2-2-085, and Singapore National Research Foundation Competitive Research Program Grant No. NRF-CRP23-2019-0007. R. W. B. is supported by the Australian Research Council Centre of Excellence for Engineered Quantum Systems (EQUS, CE170100009). W. Z. and J. G. are funded by the Singapore National Research Foundation Grant No. NRF-NRFI2017-04 (WBS No. R-144-000-378-281).

Publisher Copyright:
© 2022 American Physical Society.

ASJC Scopus subject areas

  • Physics and Astronomy (all)


Dive into the research topics of 'Observation of π/2 Modes in an Acoustic Floquet System'. Together they form a unique fingerprint.

Cite this