Computing Classical-Quantum Channel Capacity Using Blahut–Arimoto Type Algorithm: A Theoretical and Numerical Analysis †

Autor: Ning Cai, Haobo Li
Jazyk: angličtina
Rok vydání: 2020
Předmět:
Zdroj: Entropy
Volume 22
Issue 2
Entropy, Vol 22, Iss 2, p 222 (2020)
ISSN: 1099-4300
Popis: Based on Arimoto&rsquo
s work in 1972, we propose an iterative algorithm for computing the capacity of a discrete memoryless classical-quantum channel with a finite input alphabet and a finite dimensional output, which we call the Blahut&ndash
Arimoto algorithm for classical-quantum channel, and an input cost constraint is considered. We show that, to reach &epsilon
accuracy, the iteration complexity of the algorithm is upper bounded by log n log &epsilon
&epsilon
where n is the size of the input alphabet. In particular, when the output state { &rho
x } x &isin
X is linearly independent in complex matrix space, the algorithm has a geometric convergence. We also show that the algorithm reaches an &epsilon
accurate solution with a complexity of O ( m 3 log n log &epsilon
) , and O ( m 3 log &epsilon
log ( 1 - &delta
) &epsilon
D ( p * | | p N 0 ) ) in the special case, where m is the output dimension, D ( p * | | p N 0 ) is the relative entropy of two distributions,, and &delta
is a positive number. Numerical experiments were performed and an approximate solution for the binary two-dimensional case was analysed.
Databáze: OpenAIRE
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