Superadditivity of Zero-Error Capacity in Noisy Classical and Perfect Quantum Channel Pairs

• URL: http://arxiv.org/abs/2601.08913v1
• Date: Tue, 13 Jan 2026 19:00:08 GMT
• Title: Superadditivity of Zero-Error Capacity in Noisy Classical and Perfect Quantum Channel Pairs
• Authors: Ambuj, Anushko Chattopadhyay, Kunika Agarwal, Rakesh Das, Amit Mukherjee,
• Abstract summary: We demonstrate superadditivity of one-shot zero-error classical capacity in an asymmetric communication setting.<n>We show that replacing the perfect quantum channel with a perfect classical channel eliminates the effect.
• Score: 0.6524460254566904
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: We demonstrate superadditivity of one-shot zero-error classical capacity in an asymmetric communication setting where a noisy classical channel is used in parallel with a perfect quantum channel. Each channel individually supports only a fixed number of perfectly distinguishable messages. Their joint use enables transmission of strictly more messages than permitted by the product of the individual capacities. We present explicit constructions achieving this enhancement and establish that replacing the perfect quantum channel with a perfect classical channel eliminates the effect. Finally, we identify a structural criterion on the noisy channel governing this effect and show that the quantum advantage is rooted in Kochen-Specker contextuality.

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