Channel discord and distortion. (12th August 2021)

• Record Type: Journal Article
• Authors: Zhang, Wei-Wei; Sanders, Yuval R.; Sanders, Barry C.
• Is Part Of: New journal of physics. Volume 23:Number 8(2021)
• Publication Date: 2021-08-12
• Subjects: noisy measurements -- total-variation distance -- doubly stochastic channel -- channel discord -- channel distortion; Physics -- Periodicals; Physics; Periodicals; 530.05
• DOI: 10.1088/1367-2630/ac180a
• Languages: English
• ISSNs: 1367-2630

Abstract

Abstract: Discord, originally notable as a signature of bipartite quantum correlation, in fact can be nonzero classically, i.e. arising from noisy measurements by one of the two parties. Here we redefine classical discord to quantify channel distortion, in contrast to the previous restriction of classical discord to a state, and we then show a monotonic relationship between classical (channel) discord and channel distortion. We show that classical discord is equivalent to (doubly stochastic) channel distortion by numerically discovering a monotonic relation between discord and total-variation distance for a bipartite protocol with one party having a noiseless channel and the other party having a noisy channel. Our numerical method includes randomly generating doubly stochastic matrices for noisy channels and averaging over a uniform measure of input messages. Connecting discord with distortion establishes discord as a signature of classical, not quantum, channel distortion. Video Abstract: Video Abstract: Channel discord and distortion