For the first time, physicists have experimentally demonstrated the violation of “Bilocal causality”-a concept that is related to the more standard local causality, except that it accounts for the precise way in which physical systems are initially generated.
The results show that it’s possible to violate local causality in an entirely new and more general way, which could lead to a potential new resource for quantum technologies.
In general, the idea of local causality is usually taken for granted: objects can influence other objects only when they are physically close together, and any correlations between distant objects must have originated in the past when they were closer together.
To determine whether local causality has been violated, physicists perform Bell tests, which attempt to violate Bell inequalities. The researchers also showed that, in certain situations, it’s possible to violate bilocal causality but not any other type of local causality. The physicists hope that one day a loophole-free test may also be developed for bilocal causality violation.
“Experimental violation of local causality in a quantum network.” Nature Communications.