Violation of No-Signaling on a Public Quantum Computer

Abstract

No-signaling is a consequence of the no-communication theorem that states that bipartite systems cannot transfer information unless a communication channel exists. It is also a by-product of the assumptions of Bell theorem about quantum nonlocality. No-signaling is tested in bipartite systems of qubits from IBM Quantum devices in extremely large statistics, resulting in significant violations. Although the time and space scales of IBM Quantum cannot in principle rule out subluminal communications, there is no obvious physical mechanism leading to signaling. Such signaling is not universal in the relativistic but in a contextual sense. It assumes only lack of interaction between remote parts of the device. The violation is at similar level as observed in the Bell tests. It is therefore mandatory to check possible technical imperfections that may cause the violation and to repeat the loophole-free Bell test at much larger statistics, in order to rule out signaling definitively at strict space-like conditions.