Unlocking the advantage of qubit communication in multi-node network configurations

Abstract The extension of point-to-point communication to multi-node configurations has significant applications in internet and telecommunication networks. Quantum resources promise notable advantages in such settings. Here, we demonstrate a novel quantum advantage in simulating multiple access channels (MACs)-a common network configuration where multiple distant senders transmit messages to a single receiver (e.g. the uplink from several mobile phones to a server). Specifically, we show that qubit transmission outperforms its classical counterpart, even when the latter is supplemented with classical shared randomness. Remarkably, unlike the seminal quantum superdense coding protocol, this advantage is achieved without any pre-shared entanglement between the senders and the receiver-a feat prohibited by Holevo and Frenkel–Weiner no-go theorems in the one-sender-one-receiver scenario. The receiver’s ability to simultaneously decode quantum systems from multiple senders underpins this distinct advantage in the MAC setup. Some of our MAC designs are inspired by constructs in quantum foundations, such as the Pusey–Barrett–Rudolph theorem and ‘quantum nonlocality without entanglement’. Beyond network applications, this quantum advantage reveals a deeper connection to ‘quantum nonlocality without inputs’ phenomenon and suggests potential for semi-device-independent certification of entangled measurements.