Probing coherences and itinerant magnetism in a dipolar lattice gas

We report on the study of itinerant magnetism of lattice-trapped magnetic atoms, driven by magnetic dipole-dipole interactions, in the low-entropy and close-to-unit filling regime.
arXiv:2501.11402 (2025)

We have used advanced dynamical decoupling techniques to efficiently suppress the sensitivity to magnetic field fluctuations. We have thus measured the spin coherence of an itinerant spin 3 Bose dipolar gas throughout a quantum phase transition from a superfluid phase to a Mott insulating phase.

In the superfluid phase, a metastable ferromagnetic behavior is observed below a dynamical instability which occurs at lattice depths below the phase transition. In the insulating phase, the thermalization towards a paramagnetic state is driven by an interplay between intersite and superexchange interactions.

Our experiment reveals a dynamical instability in the SF regime, due to the dipolar coupling between magnons, and a new effect associated with DDIs in the strongly correlated itinerant regime. This experiment is made possible by a dynamic decoupling technique (DD), where π pulses are repeatedly applied to the sample. DD considerably increases the coherence lifetime.