Dr. Graeme Smith, IBM TJ Watson Research Center
Abstract
A quantum communication channel can be put to many uses: it can transmit classical information, private classical information, or quantum information. It can be used alone, with shared entanglement, or together with other channels. For each of these settings there is a capacity that quantifies a channel's fundamental potential for communication. In this talk, I will describe what we known about the various capacities of a quantum channel, including a discussion of synergies between different channels and related additivity questions. This will include a discussion of superactivation, where two channels each with zero capacity individually can give positive capacity when used together. I’ll also show that similar quantum “tricks” cannot be used to boost the classical capacity of optical communication systems.