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Identification via Quantum Channels in the Presence of Prior Correlation and Feedback

Andreas Winter
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Abstract

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 generalises 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.

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Andreas Winter. 2004-03-29. Identification via Quantum Channels in the Presence of Prior Correlation and Feedback. https://arxiv.org/abs/quant-ph/0403203

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