Slow convergence of Trotter decomposition for rotations

Abstract: We study the Trotter approximation for a pair of orbital angular momentum operators, $L_x$ and $L_y$. In particular, we investigate the scaling behavior of the state-dependent Trotter error. We show that for states in the domains of the orbital angular momentum operators the Trotter error scales as $n^{-1}$, where $n$ is the time discretization. Instead, the convergence rate can be arbitrarily slow for states that do not belong to the domains of all three angular momentum operators simultaneously.