Continuing our earlier work (quant-ph/0401060), we give two alternative proofs of the result that a noiseless qubit channel has identification capacity 2: the first is direct by a “maximal code with random extension” argument, the second is by showing that 1 bit of entanglement (which can be generated by transmitting 1 qubit) and negligible (quantum) communication has identification capacity 2. This generalizes a random hashing construction of Ahlswede and Dueck: that 1 shared random bit together with negligible communication has identification capacity 1. We then apply these results to prove capacity formulas for various quantum feedback channels: passive classical feedback for quantum– classical channels, a feedback model for classical–quantum channels, and “coherent feedback” for general channels.
|Translated title of the contribution||Identification Via Quantum Channels in the Presence of Prior Correlation and Feedback|
|Title of host publication||General Theory of Information Transfer and Combinatorics|
|Pages||486 - 504|
|Number of pages||19|
|Publication status||Published - 2006|