  In this letter, we will investigate causality in string field theory using
pp-wave light-cone gauge string field theory. We will generalize the Ramsey
scheme to string field theory, and use it to analyze string field theoretical
processes. An explicit characteristic function for interactive string field
theory will be built using this string field theoretical Ramsey scheme. The
average of the difference between the initial and final values of any operator
described in string field theory will be obtained using this characteristic
function. We will use the quantum information theoretical technique based on
quantum fisher information to extract information about such string field
theoretical processes.
