8,511 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
Stabilizer formalism for generalized concatenated quantum codes
The concept of generalized concatenated quantum codes (GCQC) provides a
systematic way for constructing good quantum codes from short component codes.
We introduce a stabilizer formalism for GCQCs, which is achieved by defining
quantum coset codes. This formalism offers a new perspective for GCQCs and
enables us to derive a lower bound on the code distance of stabilizer GCQCs
from component codes parameters,for both non-degenerate and degenerate
component codes. Our formalism also shows how to exploit the error-correcting
capacity of component codes to design good GCQCs efficiently.Comment: 5 pages, 2 figures, International Symposium on Information Theory, 7
July - 12 July 2013, Istanbul, Turke
Statistics of Chaotic Resonances in an Optical Microcavity
Distributions of eigenmodes are widely concerned in both bounded and open
systems. In the realm of chaos, counting resonances can characterize the
underlying dynamics (regular vs. chaotic), and is often instrumental to
identify classical-to-quantum correspondence. Here, we study, both
theoretically and experimentally, the statistics of chaotic resonances in an
optical microcavity with a mixed phase space of both regular and chaotic
dynamics. Information on the number of chaotic modes is extracted by counting
regular modes, which couple to the former via dynamical tunneling. The
experimental data are in agreement with a known semiclassical prediction for
the dependence of the number of chaotic resonances on the number of open
channels, while they deviate significantly from a purely
random-matrix-theory-based treatment, in general. We ascribe this result to the
ballistic decay of the rays, which occurs within Ehrenfest time, and
importantly, within the timescale of transient chaos. The present approach may
provide a general tool for the statistical analysis of chaotic resonances in
open systems.Comment: 5 pages, 5 figures, and a supplemental informatio
An agent-based cognitive approach for healthcare process management
Proceedings of the IEEE International Conference on Cognitive Informatics, 2009, p. 441-447Healthcare organizations are facing the challenge of delivering high-quality services through effective process management. There have been frequent changes of clinical processes and increased interactions between different functional units. To facilitate the dynamic and interactive processes in healthcare organizations, an agent-based cognitive approach is presented in this study. The emphasis is placed on dynamic clinical and administrative process management, and knowledge building as the foundation for process management. The treatment of primary open angle glaucoma is used as an example to demonstrate the effectiveness of approach for healthcare process management. © 2009 IEEE.published_or_final_versio
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