Uniform Semiclassical Observable Error Bound of Trotter–Suzuki Splitting: A Simple Algebraic Proof

Abstract. Efficient simulation of the semiclassical Schrödinger equation has garnered significant attention in the numerical analysis community. While controlling the error in the unitary evolution or the wavefunction typically requires the time step size to shrink as the semiclassical parameter [Formula: see text] decreases, it has been observed–and proved for first- and second-order Trotterization schemes–that the error in certain classes of observables admits a time step size independent of [Formula: see text]. In this work, we explicitly characterize this class of observables and present a new, simple algebraic proof of uniform-in-[Formula: see text] error bounds for arbitrarily high-order Trotterization schemes. Our proof relies solely on the algebraic structure of the underlying operators in both the continuous and discrete settings. Unlike previous analyses, it avoids Egorov-type theorems and bypasses heavy semiclassical machinery. To the best of our knowledge, this is the first proof of uniform-in-[Formula: see text] observable error bounds for Trotterization in the semiclassical regime that relies only on algebraic structure, without invoking the semiclassical limit.