Strong-Drive Floquet Engineering of Interacting Qudits: From Finite-Duration Controls to Emergent Symmetry

Abstract

Floquet driving uses periodic controls to tailor the behavior of quantum systems, with applications in quantum analogue simulation, sensing, and the protection of quantum information. Most approaches are designed using idealized, instantaneous pulses, even though experiments necessarily use pulses with finite duration and shape. This mismatch becomes especially challenging for interacting $d$-level systems, or qudits, because the number of possible controls grows rapidly with the number of levels. We develop a strong-drive Floquet theory that incorporates experimentally realizable pulse waveforms directly into the design of the effective interactions. The pulse duration, amplitude, and shape therefore become useful control parameters rather than sources of error. We show that systems with more than two levels offer capabilities unavailable in qubit systems: finite-duration driving can create new interactions that are absent from the original system and can substantially change its symmetries. We demonstrate these capabilities for interacting three-level systems. A single pulse transforms a diagonal interaction into a quantum spin-1 model dominated by nematic interactions, while pulse protocols motivated by trapped ultracold polar molecules produce models with enlarged $SU(2)\times U(1)$ and $SU(3)$ symmetries. Numerical tests of both short-time evolution and many-body dynamics confirm the accuracy of the resulting description. Our results provide a scalable analytical framework for designing finite-duration controls in interacting qudit platforms.