The absence of the selfaveraging property of the entanglement entropy of disordered free fermions in one dimension

L. Pastur

Published 2017-03-17Version 1

We consider the macroscopic system of free lattice fermions in one dimensions assuming that the one-body Hamiltonian of the system is the one dimensional discrete Schr\"odinger operator with independent identically distributed random potential. We show that the variance of the entanglement entropy of the segment $[-M,M]$ of the system is bounded away from zero as $M\rightarrow \infty $. This manifests the absence of the selfaveraging property of the entanglement entropy and shows that unlike the case of dimension two or more, where the variance of the entanglement entropy per unit surface area vanishes as $M\rightarrow \infty $, thereby guaranteing the representativity of its mean for large $M$, in the one-dimensional case the complete description of the entanglement entropy is provided by its whole probability distribution.