2025/10/18 by Abhijeet Melkani, Jayson Paulose, Melkani, Abhijeet +1 · 1 voice · 1 citation
Physics and Astronomy · #FOS: Physical sciences #Other Condensed Matter (cond-mat.other) #Quantum Mechanics and Non-Hermitian Physics #Quantum many-body systems #Topological Materials and Phenomena #cond-mat.other
paper · pdf · doi:10.48550/arxiv.2510.16562
openalex publication_date 2025/10/18 · arxiv published 2025/10/18 · arxiv updated 2025/10/18 · openalex created_date 2025/10/22 · openalex updated_date 2026/07/28
We introduce a space-time Floquet operator, a generalization of the conventional Floquet operator, that captures the long-time behavior of space-time crystals - systems where spatial and temporal periodicities are intrinsically intertwined. Unlike the standard Floquet operator, which describes evolution over a full time period, the space-time Floquet operator evolves the system over a fraction of the period, thereby resolving finer details of its dynamics. Its eigenmode spectrum defines a space-time band structure that unfolds conventional Floquet bands to respect the intertwined crystal symmetry in reciprocal wavevector-frequency space. We relate the topology of these space-time bands to quantized transport phenomena, such as Bloch oscillations and adiabatic charge transport, and uncover a fractional version of the latter. We also demonstrate how nonreciprocal parametric resonances are naturally anticipated by our framework. The approach applies broadly to both classical and quantum systems with space-time symmetry, including non-Hermitian crystals.