# P superop.m

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. Syntax:

A=p_superop(spin_system,opspec,side)

Arguments:

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.

Direct calls to this function are rarely necessary – please use operator.m unless the requested state is very exotic indeed. The function accepts operator specification in the internal Spinach notation: for each spin, identity state (or equivalently spherical tensor operator) is numbered 0, is numbered 1, is numbered 2, is numbered 3, and so on (Spinach supports all spin quantum numbers) -- irreducible spherical tensors are numbered by ascending ranks and within ranks by descending projection. The resulting sequence of integers is mapped by the kernel into the sequence of operators in the direct product. A call to **p_superop.m** with such a string as an argument would return a right or left side product superoperator corresponding to the direct product state specified.