Abstract
The maximum rate at which classical information can be reliably transmitted per use of a quantum channel strictly increases in general with N, the number of channel outputs that are detected jointly by the quantum joint-detection receiver (JDR). This phenomenon is known as superadditivity of the maximum achievable information rate over a quantum channel. We study this phenomenon for a pure-state classical-quantum channel and provide a lower bound on CN/N, the maximum information rate when the JDR is restricted to making joint measurements over no more than N quantum channel outputs, while allowing arbitrary classical error correction. We also show the appearance of a superadditivity phenomenon-of mathematical resemblance to the aforesaid problem-in the channel capacity of a classical discrete memoryless channel when a concatenated coding scheme is employed, and the inner decoder is forced to make hard decisions on N-length inner codewords. Using this correspondence, we develop a unifying framework for the above two notions of superadditivity, and show that for our lower bound to CN/N to be equal to a given fraction of the asymptotic capacity C of the respective channel, N must be proportional to V/C2, where V is the respective channel dispersion quantity.
Original language | English (US) |
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Article number | 7529100 |
Pages (from-to) | 5938-5959 |
Number of pages | 22 |
Journal | IEEE Transactions on Information Theory |
Volume | 62 |
Issue number | 10 |
DOIs | |
State | Published - Oct 2016 |
Keywords
- Concatenated codes
- Holevo capacity
- Pure-state classical input-quantum output (cq) channel
- joint measurement
- superadditivity of capacity
ASJC Scopus subject areas
- Information Systems
- Computer Science Applications
- Library and Information Sciences