Exact kinetic propagators for coherent state complex Langevin simulations

We introduce and benchmark an improved algorithm for complex Langevin
simulations of bosonic coherent state path integrals in the preprint. Our
approach utilizes a Strang splitting of the imaginary-time propagator
rather than the conventional linear-order Taylor expansion, allowing us to
construct an action that incorporates higher-order terms at negligible
computational cost. The resulting algorithm enjoys guaranteed linear
stability independent of the imaginary-time discretization, enabling more
resource-efficient simulations. We demonstrate this improved performance
for single-species bosons and for two-component bosons with Rashba
spin-orbit coupling. The enclosed data set shows a method comparison
between the standard "primitive" approach and the quadratic
propagator technique used in this manuscript for many thermodynamic
observables of interest.