A method for exponential operator decomposition
  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. 
Seckin Sefi, Peter van Loock
quant-ph