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 input size.
|Titolo:||Quantum capacity of dephasing channels with memory|
|Data di pubblicazione:||2007|
|Citazione:||Quantum capacity of dephasing channels with memory / A. D'Arrigo; G. Benenti; Falci G. - In: NEW JOURNAL OF PHYSICS. - ISSN 1367-2630. - 9(2007), pp. 310-321.|
|Appare nelle tipologie:||1.1 Articolo in rivista|