Entangled in Tops: How we turned the LHC into the world’s biggest quantum experiment

by Ethan Lewis Simpson (University of Glasgow (GB))

Friday 10 Nov 2023, 13:00 → 14:00 Europe/London

Niels Bohr Seminar Room (Schuster)

A month ago, Claudio explained how quantum information properties can be examined in top-quark production, and introduced the recent ATLAS measurement of quantum entanglement -- to considerable controversy.  As one of the lead analysers on this measurement, in this sequel talk I will attempt to allay fears and answer questions by examining the ATLAS result in greater detail. Focusing first on specific entanglement criteria borrowed from quantum information science, I will justify why we can observe entanglement by measuring a single observable. The intricacies of the measurement, the experimental challenges, and the lessons learned for precision top measurements, will be presented. In particular, discrepancies between different modelling tools, and possibles shortcoming in simulations, will be examined. This ATLAS measurement was the first to observe quantum entanglement between fundamental quarks, and opens up an exciting new field within high-energy physics; future measurements -- and their utility in searching for new physics -- will therefore also be discussed.