2,580 research outputs found
Algorithmic Superactivation of Asymptotic Quantum Capacity of Zero-Capacity Quantum Channels
The superactivation of zero-capacity quantum channels makes it possible to
use two zero-capacity quantum channels with a positive joint capacity for their
output. Currently, we have no theoretical background to describe all possible
combinations of superactive zero-capacity channels; hence, there may be many
other possible combinations. In practice, to discover such superactive
zero-capacity channel-pairs, we must analyze an extremely large set of possible
quantum states, channel models, and channel probabilities. There is still no
extremely efficient algorithmic tool for this purpose. This paper shows an
efficient algorithmical method of finding such combinations. Our method can be
a very valuable tool for improving the results of fault-tolerant quantum
computation and possible communication techniques over very noisy quantum
channels.Comment: 35 pages, 17 figures, Journal-ref: Information Sciences (Elsevier,
2012), presented in part at Quantum Information Processing 2012 (QIP2012),
v2: minor changes, v3: published version; Information Sciences, Elsevier,
ISSN: 0020-0255; 201
Information Geometric Security Analysis of Differential Phase Shift Quantum Key Distribution Protocol
This paper analyzes the information-theoretical security of the Differential
Phase Shift (DPS) Quantum Key Distribution (QKD) protocol, using efficient
computational information geometric algorithms. The DPS QKD protocol was
introduced for practical reasons, since the earlier QKD schemes were too
complicated to implement in practice. The DPS QKD protocol can be an integrated
part of current network security applications, hence it's practical
implementation is much easier with the current optical devices and optical
networks. The proposed algorithm could be a very valuable tool to answer the
still open questions related to the security bounds of the DPS QKD protocol.Comment: 42 pages, 34 figures, Journal-ref: Security and Communication
Networks (John Wiley & Sons, 2012), presented in part at the IEEE Int.
Conference on Network and Service Security (IEEE N2S 2009
Resolvability on Continuous Alphabets
We characterize the resolvability region for a large class of point-to-point
channels with continuous alphabets. In our direct result, we prove not only the
existence of good resolvability codebooks, but adapt an approach based on the
Chernoff-Hoeffding bound to the continuous case showing that the probability of
drawing an unsuitable codebook is doubly exponentially small. For the converse
part, we show that our previous elementary result carries over to the
continuous case easily under some mild continuity assumption.Comment: v2: Corrected inaccuracies in proof of direct part. Statement of
Theorem 3 slightly adapted; other results unchanged v3: Extended version of
camera ready version submitted to ISIT 201
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