Entropy and exact matrix-product representation of the laughlin wave function

Abstract

An analytical expression for the von Neumann entropy of the Laughlin wave function is obtained for any possible bipartition between the particles described by this wave function, for a filling fraction ν=1. Also, for a filling fraction ν=1/m, where m is an odd integer, an upper bound on this entropy is exhibited. These results yield a bound on the smallest possible size of the matrices for an exact representation of the Laughlin ansatz in terms of a matrix-product state. An analytical matrix-product state representation of this state is proposed in terms of representations of the Clifford algebra. For ν=1, this representation is shown to be asymptotically optimal in the limit of a large number of particles. © 2007 The American Physical Society.