The Multiple-Access Channel with Entangled Transmitters

Communication over a classical multiple-access channel (MAC) with entanglement resources is considered, whereby two transmitters share entanglement resources a priori before communication begins. Leditzki et al. (2020) presented an example of a classical MAC, defined in terms of a pseudo telepathy game, such that the sum rate with entangled transmitters is strictly higher than the best achievable sum rate without such resources. Here, we derive a full characterization of the capacity region for the general MAC with entangled transmitters, and show that the previous result can be obtained as a special case. A single-letter formula is established involving auxiliary variables and ancillas of finite dimensions. This, in turn, leads to a sufficient entanglement rate to achieve the rate region.