A lower bound on entanglement-assisted quantum communication complexity

Abstract

We prove a general lower bound on the bounded-error entanglement-assisted quantum communication complexity of Boolean functions. The bound is based on the concept that any classical or quantum protocol to evaluate a function on distributed inputs can be turned into a quantum communication protocol. As an application of this bound, we give a very simple proof of the statement that almost all Boolean functions on n + n bits have communication complexity linear in n, even in the presence of unlimited entanglement. © Springer-Verlag Berlin Heidelberg 2007.