241 research outputs found
Enhanced Feedback Iterative Decoding of Sparse Quantum Codes
Decoding sparse quantum codes can be accomplished by syndrome-based decoding
using a belief propagation (BP) algorithm.We significantly improve this
decoding scheme by developing a new feedback adjustment strategy for the
standard BP algorithm. In our feedback procedure, we exploit much of the
information from stabilizers, not just the syndrome but also the values of the
frustrated checks on individual qubits of the code and the channel model.
Furthermore we show that our decoding algorithm is superior to belief
propagation algorithms using only the syndrome in the feedback procedure for
all cases of the depolarizing channel. Our algorithm does not increase the
measurement overhead compared to the previous method, as the extra information
comes for free from the requisite stabilizer measurements.Comment: 10 pages, 11 figures, Second version, To be appeared in IEEE
Transactions on Information Theor
Finite-Block-Length Analysis in Classical and Quantum Information Theory
Coding technology is used in several information processing tasks. In
particular, when noise during transmission disturbs communications, coding
technology is employed to protect the information. However, there are two types
of coding technology: coding in classical information theory and coding in
quantum information theory. Although the physical media used to transmit
information ultimately obey quantum mechanics, we need to choose the type of
coding depending on the kind of information device, classical or quantum, that
is being used. In both branches of information theory, there are many elegant
theoretical results under the ideal assumption that an infinitely large system
is available. In a realistic situation, we need to account for finite size
effects. The present paper reviews finite size effects in classical and quantum
information theory with respect to various topics, including applied aspects
Proof-of-Concept of Real-World Quantum Key Distribution with Quantum Frames
We propose and experimentally investigate a fibre-based quantum key
distribution system, which employs polarization qubits encoded into faint laser
pulses. As a novel feature, it allows sending of classical framing information
via sequences of strong laser pulses that precede the quantum data. This allows
synchronization, sender and receiver identification, and compensation of
time-varying birefringence in the communication channel. In addition, this
method also provides a platform to communicate implementation specific
information such as encoding and protocol in view of future optical quantum
networks. Furthermore, we report on our current effort to develop high-rate
error correction.Comment: 25 pages, 14 figures, 4 table
Multi-factor Physical Layer Security Authentication in Short Blocklength Communication
Lightweight and low latency security schemes at the physical layer that have
recently attracted a lot of attention include: (i) physical unclonable
functions (PUFs), (ii) localization based authentication, and, (iii) secret key
generation (SKG) from wireless fading coefficients. In this paper, we focus on
short blocklengths and propose a fast, privacy preserving, multi-factor
authentication protocol that uniquely combines PUFs, proximity estimation and
SKG. We focus on delay constrained applications and demonstrate the performance
of the SKG scheme in the short blocklength by providing a numerical comparison
of three families of channel codes, including half rate low density parity
check codes (LDPC), Bose Chaudhuri Hocquenghem (BCH), and, Polar Slepian Wolf
codes for n=512, 1024. The SKG keys are incorporated in a zero-round-trip-time
resumption protocol for fast re-authentication. All schemes of the proposed
mutual authentication protocol are shown to be secure through formal proofs
using Burrows, Abadi and Needham (BAN) and Mao and Boyd (MB) logic as well as
the Tamarin-prover
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