Many-body XXZ Ramsey dynamics in a tunable NV simulator

Dense, interacting ensembles of NV centers in diamond not only offer state-of-the-art sensing capabilities under ambient conditions, but also present a unique quantum simulation platform for long-ranged quantum magnetism. In particular, Ramsey dynamics provide a simple probe of many-body spin systems out of equilibrium, and can yield metrologically useful spin squeezed states if suitably controlled. We present recent experimental data and numerical simulations on the Ramsey dynamics as a function of the anisotropy parameter in the paradigmatic XXZ Hamiltonian. Although heuristic arguments in the NMR literature predict pure exponential decay of uniformly polarized states for all underlying XXZ Hamiltonians, we observe striking features near the XY and Heisenberg Hamiltonians. We describe theoretical progress toward understanding these features as a consequence of emergent collective behavior. We also highlight our recent innovations in pulse sequence design that enable these measurements, which should be applicable to many other physical systems.