Problem
Research questions and friction points this paper is trying to address.
generalized amplitude-damping channel
classical capacity
quantum Shannon theory
A pretty-tight converse on the classical capacity of generalized amplitude-damping channels
🤖 AI Summary
研究通过改进Brandão等人的方法，为广义振幅阻尼信道的经典容量提供了一个可有效计算且较为紧致的上界。
📝 Abstract
The classical capacity of a quantum channel is the highest rate at which classical information can be transmitted with vanishing error. Although the capacities of many fundamental quantum channels have been established, the capacity of the generalized amplitude-damping channel remains an open problem in quantum Shannon theory. In this work, we revisit a converse bound introduced by Brandão et al. [Phys. Rev. Lett. 106, 230502 (2011)], which upper-bounds the classical capacity in terms of a correlation measure. For the generalized amplitude-damping channel, we derive a relaxation of this measure that makes the converse bound efficiently computable. Numerical comparisons demonstrate that our bound is pretty tight in general and nearly coincides with the Holevo information at nonzero temperatures, significantly improving upon existing bounds across the entire parameter range.
Innovation
Methods, ideas, or system contributions that make the work stand out.
generalized amplitude-damping channel
converse bound
correlation measure relaxation
efficient computation
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