Unlocking Exponential and Unbounded Robust Gains in Shannon Capacity of Classical Multiple Access Channels with Causal CSIT via Quantum Entanglement Assistance
Year: 2026
Type: article
Abstract: Quantum entanglement assistance is known to improve the Shannon capacity of classical communication networks but the largest gains noted thus far are rather modest (less than 6%), motivating the question: arelargecapacity gains ever possible? It is shown in this work that in the presence of causal channel state information at the transmitters (CSIT), quantum entanglement assistance provides a multiplicative capacity advantage that grows exponentially with the number of usersKfor certain classicalK-user multiple access channels with fixed size (binary) alphabet for inputs, outputs and states. Similarly, in the presence of causal channel state information at the transmitters, quantum entanglement assistance is shown to provide a multiplicative capacity advantage that is unbounded as the size of the state alphabet grows, while the number of users (K= 3) and the input and output alphabet (binary) are held fixed. Even with only a few users and small alphabet sizes, substantial multiplicative gains in capacity are found, e.g., with binary inputs, outputs and states, multiplicative gains by factors exceeding 21 and 88 are noted withK= 5 andK= 7 users, respectively. The gains are robust in the sense that they persist even with noisy quantum resources, e.g., an exponential (inK) capacity advantage from quantum entanglement assistance remains available even if each entangled qubit independently depolarizes completely with probability ≈ 30%. The gains are based on quantum entanglement assistance provided only to the transmitters.
Authors: Yuhang Yao, Syed A. Jafar
Institution: University of California, Irvine
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $2,645
Funder: Army Research Office
OpenAlex ID: W7163679307