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Floquet product mode and eigenphase order

Felix Möckel1, Harald Schmid1,2,3, and Felix von Oppen4

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Phys. Rev. B 114, 165138 – Published 24 September, 2026

DOI: https://doi.org/10.1103/64fp-6gy7

Abstract

We study the robustness of the Floquet quantum Ising model against integrability-breaking perturbations, focusing on the phase hosting both Majorana zero and π modes. A recent work [H.-C. Yeh, A. Rosch, and A. Mitra, Phys. Rev. B 110, 075117 (2024)] observed that the Floquet product mode, a composite edge mode constructed from both Majorana operators, is considerably more robust than the individual Majorana edge modes. We analyze these strong modes from the point of view of the eigenphase order present in finite chains with open boundary conditions. As a result of the Majorana modes, all Floquet eigenstates come in quadruplets in the integrable limit. We show that the robustness of the various modes as well as the behavior of the boundary spin correlation functions can be understood in terms of the spectral statistics of these quadruplets in the presence of integrability-breaking perturbations.

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Phys. Rev. B 114, 165138– Published 24 September, 2026
  • Received 30 March 2026
  • Revised 21 July 2026
  • Accepted 8 September 2026
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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