Using dynamical decoupling to investigate magnetism of large-spin atoms
Phys. Rev. A 113, 033306 – Published 9 March, 2026
DOI: https://doi.org/10.1103/jm4k-wg56
Abstract
We present a detailed investigation of itinerant magnetism in a dipolar Bose gas of chromium atoms confined in a three-dimensional optical lattice, expanding on results recently reported in [Phys. Rev. Lett. 136, 103401 (2026)]. In the low-entropy, near-unit filling regime, we employ advanced dynamical decoupling techniques to suppress magnetic-field noise and probe spin coherence across the superfluid–Mott insulator transition. Here, we provide a systematic comparison of different dynamical decoupling sequences, analyze their robustness to experimental imperfections, and quantify their impact on spin dynamics. We also develop perturbative and effective-model approaches that capture the role of both contact and dipolar interactions in determining spin coherence. In the superfluid regime, we discuss a hydrodynamic description that elucidates the emergence and breakdown of metastable ferromagnetism. In the insulating regime, we derive effective spin models including superexchange terms. In this limit, we introduce a tractable spin-1 toy model and a short-time expansion of the full spin-3 dynamics that help to shed insight on the interplay between dipolar and contact-driven superexchange dynamics observed experimentally for spin-3. Our comprehensive analysis bridges experiment and theory, providing new tools and perspectives for understanding itinerant dipolar magnetism in optical lattices.
