  Quantum simulation of 1D relativistic quantum mechanics has been achieved in
well-controlled systems like trapped ions, but properties like spin dynamics
and response to external magnetic fields that appear only in higher dimensions
remain unexplored. Here we simulate the dynamics of a 2D Weyl particle. We show
the linear dispersion relation of the free particle and the discrete Landau
levels in a magnetic field, and we explicitly measure the spatial and spin
dynamics from which the conservation of helicity and properties of
antiparticles can be verified. Our work extends the application of an ion trap
quantum simulator in particle physics with the additional spatial and spin
degrees of freedom.
