Time-dependent correlation function of the Jordan-Wigner operator as a Fredholm determinant

Abstract

We calculate a correlation function of the Jordan-Wigner operator in a class of free-fermion models formulated on an infinite one-dimensional lattice. We represent this function in terms of the determinant of an integrable Fredholm operator, convenient for analytic and numerical investigations. By using Wick's theorem, we avoid the form-factor summation customarily used in literature for treating similar problems.

references added, introduction and conclusion modified, version accepted for publication in J. Stat. Mech