Comments on Hastings' Additivity Counterexamples
Published Web Locationhttps://arxiv.org/pdf/0905.3697.pdf
Hastings recently provided a proof of the existence of channels which violate the additivity conjecture for minimal output entropy. In this paper we present an expanded version of Hastings' proof. In addition to a careful elucidation of the details of the proof, we also present bounds for the minimal dimensions needed to obtain a counterexample.