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Quantum Capacity of a dephasing channel with memory

Antonio D'Arrigo·Giuliano Benenti·Giuseppe Falci
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Abstract

We show that the amount of coherent quantum information that can be reliably transmitted down a dephasing channel with memory is maximized by separable input states. In particular, we model the channel as a Markov chain or a multimode environment of oscillators. While in the first model the maximization is achieved for the maximally mixed input state, in the latter it is convenient to exploit the presence of a decoherence-protected subspace generated by memory effects. We explicitly compute the quantum channel capacity for the first model while numerical simulations suggest a lower bound for the latter. In both cases memory effects enhance the coherent information. We present results valid for arbitrary size of the input.

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Antonio D'Arrigo, Giuliano Benenti, Giuseppe Falci. 2007-08-03. Quantum Capacity of a dephasing channel with memory. https://doi.org/10.1088/1367-2630%2F9%2F9%2F310

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