Abstract
Several relations between the Holevo capacity and entanglement-assisted classical capacity of a quantum channel are proved; necessary and sufficient conditions for their coincidence are obtained. In particular, it is shown that these capacities coincide if (respectively, only if) the channel (respectively, the χ-essential part of the channel) belongs to the class of classical-quantum channels (the χ-essential part is a restriction of a channel obtained by discarding all states that are useless for transmission of classical information). The obtained conditions and their corollaries are generalized to channels with linear constraints. By using these conditions it is shown that the question of coincidence of the Holevo capacity and entanglement-assisted classical capacity depends on the form of a constraint. Properties of the difference between quantum mutual information and the χ-function of a quantum channel are explored.
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References
Bennett, C.H., Shor, P.W., Smolin, J.A., and Thapliyal, A.V., Entanglement-Assisted Classical Capacity of Noisy Quantum Channel, Phys. Rev. Lett., 1999, vol. 83, no. 15, pp. 3081–3084.
Holevo, A.S., Kvantovye sistemy, kanaly, informatsiya (Quantum Systems, Channels, and Information), Moscow: MCCME, 2010.
Nielsen, M.A. and Chuang, I.L., Quantum Computation and Quantum Information, Cambridge: Cambridge Univ. Press, 2000. Translated under the title Kvantovye vychisleniya i kvantovaya informatsiya, Moscow: Mir, 2006.
Hastings, M.B., Superadditivity of Communication Capacity Using Entangled Inputs, Nature Physics, 2009, vol. 5, no. 4, pp. 255–257.
Bennett, C.H., Shor, P.W., Smolin, J.A., and Thapliyal, A.V., Entanglement-Assisted Capacity of a Quantum Channel and the Reverse Shannon Theorem, IEEE Trans. Inform. Theory, 2002, vol. 48, no. 10, pp. 2637–2655.
Holevo, A.S., Information Capacity of a Quantum Observable, Probl. Peredachi Inf., 2012, vol. 48, no. 1, pp. 3–14 [Probl. Inf. Trans. (Engl. Transl.), 2012, vol. 48, no. 1, pp. 1–10].
Holevo, A.S., Complementary Channels and the Additivity Problem, Teor. Veroyatnost. i Primenen., 2006, vol. 51, no. 1, pp. 133–143 [Theory Probab. Appl. (Engl. Transl.), 2007, vol. 51, no. 1, pp. 92–100].
Holevo, A.S. and Shirokov, M.E., On Shor’s Channel Extension and Constrained Channels, Comm. Math. Phys., 2004, vol. 249, no. 2, pp. 417–430.
Schumacher, B. and Westmoreland, M.D., Optimal Signal Ensembles, Phys. Rev. A, 2001, vol. 63, no. 2, p. 022308 (electronic).
Holevo, A.S., Remarks on the Classical Capacity of Quantum Covariant Channels, ArXiv e-print arXiv: quant-ph/0212025, 2002.
Fan, H., Remarks on Entanglement Assisted Classical Capacity, Phys. Lett. A, 2003, vol. 313, no. 3, pp. 182–187.
Schumacher, B. and Westmoreland, M.D., Quantum Privacy and Quantum Coherence, Phys. Rev. Lett., 1998, vol. 80, no. 25, pp. 5695–5697.
Hayden, P., Jozsa, R., Petz, D., and Winter, A., Structure of States Which Satisfy Strong Subadditivity of Quantum Entropy with Equality, Commun. Math. Phys., 2004, vol. 246, no. 2, pp. 359–374.
Cubitt, T., Ruskai, M.-B., and Smith, G., The Structure of Degradable Quantum Channels, J. Math. Phys., 2008, vol. 49, no. 10, p. 102104 (electronic).
Fukuda, M. and Holevo, A.S., OnWeyl-Covariant Channels, ArXiv e-print arXiv:quant-ph/0510148v3, 2006.
Holevo, A.S., Classical Capacities of a Quantum Channel with a Restriction at the Input, Teor. Veroyatnost. i Primenen., 2003, vol. 48, no. 2, pp. 359–374 [Theory Probab. Appl. (Engl. Transl.), 2004, vol. 48, no. 2, pp. 243–255].
Audenaert, K.M.R. and Braunstein, S.L., On Strong Superadditivity of the Entanglement of Formation, Comm. Math. Phys., 2004, vol. 246, no. 3, pp. 443–452.
Shirokov, M.E., A Criterion for Coincidence of the Entanglement-Assisted Classical Capacity and the Holevo Capacity of a Quantum Channel, ArXiv e-print arXiv:quant-ph/1202.3449v2, 2012.
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Original Russian Text © M.E. Shirokov, 2012, published in Problemy Peredachi Informatsii, 2012, Vol. 48, No. 2, pp. 3–20.
Supported in part by the Scientific Program “Mathematical Control Theory and Dynamic Systems” of the Russian Academy of Sciences and the Russian Foundation for Basic Research, project nos. 10-01-00139-a and 12-01-00319-a.
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Shirokov, M.E. Conditions for coincidence of the classical capacity and entanglement-assisted capacity of a quantum channel. Probl Inf Transm 48, 85–101 (2012). https://doi.org/10.1134/S0032946012020019
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DOI: https://doi.org/10.1134/S0032946012020019