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Entangled Inputs Cannot Make Imperfect Quantum Channels Perfect

Brandão, F. G. S. L. and Eisert, J. and Horodecki, M. and Yang, D. (2011) Entangled Inputs Cannot Make Imperfect Quantum Channels Perfect. Physical Review Letters, 106 (23). Art. No. 230502. ISSN 0031-9007. doi:10.1103/PhysRevLett.106.230502.

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Entangled inputs can enhance the capacity of quantum channels, this being one of the consequences of the celebrated result showing the nonadditivity of several quantities relevant for quantum information science. In this work, we answer the converse question (whether entangled inputs can ever render noisy quantum channels to have maximum capacity) to the negative: No sophisticated entangled input of any quantum channel can ever enhance the capacity to the maximum possible value, a result that holds true for all channels both for the classical as well as the quantum capacity. This result can hence be seen as a bound as to how “nonadditive quantum information can be.” As a main result, we find first practical and remarkably simple computable single-shot bounds to capacities, related to entanglement measures. As examples, we discuss the qubit amplitude damping and identify the first meaningful bound for its classical capacity.

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Brandão, F. G. S. L.0000-0003-3866-9378
Additional Information:© 2011 American Physical Society. (Received 26 November 2010; published 10 June 2011) We thank M. Christandl, A. Harrow, M. P. Müller, and A. Winter for useful feedback. F. G. S. L. B. is supported by the Brazilian agency Fundação de Amparo a Pesquisa do Estado de Minas Gerais (FAPEMIG). J. E. is supported by the EU (QESSENCE, MINOS, COMPAS), the BMBF (QuOReP), and the EURYI. M. H. is supported by MNiSW Grant No. N202 231937 and by the EU (QESSENCE). D. Y. is supported by NSFC (Grant No. 10805043). Part of this work was done in KCIK. F. G. S. L. B., J. E., and M. H. are thankful for the hospitality of the Mittag-Leffler institute, where part of this work has been done.
Funding AgencyGrant Number
Fundação de Amparo a Pesquisa do Estado de Minas Gerais (FAPEMIG)UNSPECIFIED
Bundesministerium für Bildung und Forschung (BMBF)UNSPECIFIED
European Young Investigator Awards (EURYI)UNSPECIFIED
Ministerstwo Nauki i Szkolnictwa Wyższego (MNiSzW)N202 231937
National Natural Science Foundation of China10805043
Issue or Number:23
Classification Code:PACS numbers: 03.67.Hk, 03.67.Ac
Record Number:CaltechAUTHORS:20160607-102352442
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:67718
Deposited By: George Porter
Deposited On:07 Jun 2016 18:45
Last Modified:11 Nov 2021 03:53

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