  Exponential operator decompositions are an important tool in many fields of
physics, for example, in quantum control, quantum computation, or condensed
matter physics. In this work, we present a method for obtaining such
decompositions, which is efficient in terms of the required number of
operators. Compared to existing schemes, our more direct approach is general,
in the sense that it can be applied to various kinds of operators including
nested commutation operators, and it is systematic.
