Surprises in the theory of quantum channel capacity

          @misc{ pirsa_PIRSA:08120029,
            doi = {10.48660/08120029},
            url = {https://pirsa.org/08120029},
            author = {Yard, Jon},
            keywords = {Quantum Information},
            language = {en},
            title = {Surprises in the theory of quantum channel capacity},
            publisher = {Perimeter Institute},
            year = {2008},
            month = {dec},
            note = {PIRSA:08120029 see, \url{https://pirsa.org}}
          }
          

Abstract

A quantum channel models a physical process which adds noise to a quantum system by interacting with the environment. Protecting quantum systems from such noise can be viewed as an extension of the classical communication problem introduced by Shannon sixty years ago. A fundamental quantity of interest is the quantum capacity of a given channel. It measures the amount of quantum information that can be transmitted with vanishing error, in the limit of many independent transmissions over that channel. In this talk, I will show that certain pairs of channels, each with a capacity of zero, can have a strictly positive capacity when used together. This unveils a rich structure in the theory of quantum communication that is absent from Shannon\'s classical theory. This is joint work with Graeme Smith (IBM) which was published in the Sept. 26 issue of Science.