sigmoid operator operators that change coefficients of kets, but not the structure of the input sequence the most commonly used sigmoid operator is the clean sigmoid that just sets coefficients to either 1 or 0
the |sp> => rank split |abcde> the |sp> |a> + 2|b> + 3|c> + 4|d> + 5|e> clean the |sp> |a> + |b> + |c> + |d> + |e>