title: Bipartite subspaces having no bases distinguishable by local operations and classical communication.
abstract: It is proved that there exist subspaces of bipartite tensor product spaces that have no orthonormal bases that can be perfectly distinguished by means of local operations and classical communication. A corollary of this fact is that there exist quantum channels having suboptimal classical capacity even when the receiver may communicate classically with a third party that represents the channel's environment.
authors.affiliation: Institute for Quantum Information Science and Department of Computer Science, University of Calgary, Calgary, Alberta, Canada T2N 1N4. jwatrous@cpsc.ucalgary.ca
authors.forename: John
authors.initials: J
authors.lastname: Watrous