From Spinach Documentation Wiki
Sided product superoperator in the spherical tensor basis set. Returns superoperators corresponding to right or left multiplication of a density matrix by a user-specified operator.
opspec - Spinach operator specification described in Sections 2.1 and 3.3 of the following paper: http://dx.doi.org/10.1016/j.jmr.2010.11.008 side - 'left' or 'right' causes the function to return a product superoperator corresponding to a product from that side; 'comm' or 'acomm' results in commutation and anticommuta- tion superoperator respectively.
A - a three-column array of row indices (first column), column indices (second column) and values (third column).
- This is a very general function to which direct calls are not usually required - please use the much friendlier operator.m function.
- The superoperator is returned in XYZ sparse format, which is different from Matlab's CSC format.