Observation of quantum entanglement in top quark pairs at the ATLAS experiment

The ATLAS Collaboration has recently reported the first observation of quantum entanglement in top quark pair production at the Large Hadron Collider (LHC). A brief review of the experimental status of top quark pair spin correlations is given, before highlighting the expected differences between classical and quantum correlations. A criterion for the detection of spin entanglement in top quark pairs has been proposed; the experimental strategy to implement it and observe the effect is discussed, and the positive results of the ATLAS measurement are presented.