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Postselection Technique for Quantum Channels with Applications to Quantum Cryptography

Christandl, Matthias and König, Robert and Renner, Renato (2009) Postselection Technique for Quantum Channels with Applications to Quantum Cryptography. Physical Review Letters, 102 (2). Art. No. 020504. ISSN 0031-9007.

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We propose a general method for studying properties of quantum channels acting on an n-partite system, whose action is invariant under permutations of the subsystems. Our main result is that, in order to prove that a certain property holds for an arbitrary input, it is sufficient to consider the case where the input is a particular de Finetti-type state, i.e., a state which consists of n identical and independent copies of an (unknown) state on a single subsystem. Our technique can be applied to the analysis of information-theoretic problems. For example, in quantum cryptography, we get a simple proof for the fact that security of a discrete-variable quantum key distribution protocol against collective attacks implies security of the protocol against the most general attacks. The resulting security bounds are tighter than previously known bounds obtained with help of the exponential de Finetti theorem.

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Additional Information:© 2009 The American Physical Society. Received 17 September 2008; published 14 January 2009. R.K. acknowledges support from NSF Grants No. PHY-0456720 and No. PHY-0803371. R.R. received support from the EU project SECOQC.
Funding AgencyGrant Number
National Science FoundationPHY-0456720
National Science FoundationPHY-0803371
European UnionSECOQC
Issue or Number:2
Record Number:CaltechAUTHORS:CHRIprl09
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:13106
Deposited By: Archive Administrator
Deposited On:21 Jan 2009 18:05
Last Modified:03 Oct 2019 00:34

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