Entanglement of random subspaces via the Hastings bound

TL;DR

This paper extends Hastings' method to establish new bounds on the entanglement of random subspaces in bipartite systems, demonstrating the existence of non-unital channels that violate additivity of minimal output entropy.

Contribution

It introduces novel bounds for entanglement in random subspaces and applies them to show non-unital channels can violate additivity, advancing understanding of quantum channel capacities.

Findings

New bounds for entanglement of random subspaces

Existence of non-unital channels violating additivity

Extension of Hastings' method to bipartite systems

Abstract

Recently Hastings proved the existence of random unitary channels which violate the additivity conjecture. In this paper we use Hastings' method to derive new bounds for the entanglement of random subspaces of bipartite systems. As an application we use these bounds to prove the existence of non-unital channels which violate additivity of minimal output entropy.