2008/07/31 by Graeme Smith, Jon Yard · 1 citation
Physics and Astronomy · #quant-ph
paper · pdf · doi:10.1126/science.1162242
published as Science 321, 1812 - 1815 (2008) · Final submitted version
arxiv created 2009/02/20 · arxiv updated 2009/12/01
Communication over a noisy quantum channel introduces errors in the transmission that must be corrected. A fundamental bound on quantum error correction is the quantum capacity, which quantifies the amount of quantum data that can be protected. We show theoretically that two quantum channels, each with a transmission capacity of zero, can have a nonzero capacity when used together. This unveils a rich structure in the theory of quantum communications, implying that the quantum capacity does not uniquely specify a channel's ability for transmitting quantum information.