Anshu, AnuragJain, RahulWarsi, Naqueeb Ahmad2024-04-172019-01-01Anshu, Anurag, Rahul Jain, Naqueeb Ahmad Warsi. "On the near-optimality of one-shot classical communication over quantum channels." No Journal 60, no. 1 (2019). DOI: 10.1063/1.50397960022-24881089-7658https://nrs.harvard.edu/URN-3:HUL.INSTREPOS:37378350We study the problem of transmission of classical messages through a quantum channel in several network scenarios in the one-shot setting. We consider both the entanglement assisted and unassisted cases for the point to point quantum channel, quantum multiple-access channel, quantum channel with state and the quantum broadcast channel. We show that it is possible to near-optimally characterize the amount of communication that can be transmitted in these scenarios, using the position-based decoding strategy introduced in a prior work [Anshu, Jain and Warsi, 2017]. In the process, we provide a short and elementary proof of the converse for entanglement-assisted quantum channel coding in terms of the quantum hypothesis testing divergence (obtained earlier in [Matthews and Wehner, 2014]). Our proof has the additional utility that it naturally extends to various network scenarios mentioned above. Furthermore, none of our achievability results require a simultaneous decoding strategy, existence of which is an important open question in quantum Shannon theory.en-USMathematical PhysicsStatistical and Nonlinear PhysicsJournal Article2024-04-1710.1063/1.5039796