Fudan team extracts CKM matrix element |Vus| via quantum entanglement in collider experiment for the first time
On the evening of September 2, 2026, Beijing time, the team led by Luo Tao from the Institute of Modern Physics at Fudan University, together with collaborators, published a research achievement titled "Exploring baryon semileptonic decays through polarization and entanglement" in Nature. This study, for the first time in a collider experiment, utilized quantum entanglement and polarization information to extract the Cabibbo-Kobayashi-Maskawa (CKM) matrix element |Vus|, providing a new experimental pathway for precisely testing the Standard Model of particle physics. The CKM matrix describes the strength of transitions between different quarks under the weak interaction. Among them, |Vus| corresponds to the transition from the strange quark to the up quark, and its numerical precision is related to the test of the three-generation quark mixing mechanism in the Standard Model. Currently, results for |Vus| obtained from different decay processes still show discrepancies, and the unitarity test of the first row of the CKM matrix also exhibits some tension, necessitating more independent measurement methods for verification.
2026-09-04
