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arXiv · 2308.02143

Floquet systems with continuous dynamical symmetries: characterization, time-dependent Noether charge, and solvability

Yukio Kaneko·Tatsuhiko N. Ikeda
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Abstract

We study quantum Floquet (periodically-driven) systems having continuous dynamical symmetry (CDS) consisting of a time translation and a unitary transformation on the Hilbert space. Unlike the discrete ones, the CDS strongly constrains the possible Hamiltonians $H(t)$ and allows us to obtain all the Floquet states by solving a finite-dimensional eigenvalue problem. Besides, Noether's theorem leads to a time-dependent conservation charge, whose expectation value is time-independent throughout evolution. We exemplify these consequences of CDS in the seminal Rabi model, an effective model of a nitrogen-vacancy center in diamonds without strain terms, and Heisenberg spin models in rotating fields. Our results provide a systematic way of solving for Floquet states and explain how they avoid hybridization in quasienergy diagrams.

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Yukio Kaneko, Tatsuhiko N. Ikeda. 2023-08-04. Floquet systems with continuous dynamical symmetries: characterization, time-dependent Noether charge, and solvability. https://doi.org/10.1088/1402-4896%2Fad5f63

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