Violation of no-signaling on a public quantum computer

TL;DR

This study tests the no-signaling principle in IBM Quantum devices and finds significant violations, highlighting the need for further investigation to rule out technical imperfections and confirm fundamental quantum assumptions.

Contribution

First large-scale experimental test of no-signaling violations on a public quantum computer, revealing potential technical issues affecting quantum nonlocality tests.

Findings

Significant violations of no-signaling observed in IBM Quantum devices

Violations comparable to those seen in Bell tests

Highlights the need for further loophole-free experiments

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. We have tested no-signaling 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. The violation is also at similar level as observed in 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 be ruled out definitively at strict spacelike conditions.