RT Journal Article T1 Entanglement and quantum tomography with top quarks at the LHC A1 Afik, Yoav A1 Muñoz de Nova, Juan Ramón AB Entanglement is a central subject in quantum mechanics. Due to its genuine relativistic behavior and fundamental nature, high-energy colliders are attractive systems for the experimental study of fundamental aspects of quantum mechanics. We propose the detection of entanglement between the spins of top–antitop–quark pairs at the LHC, representing the first proposal of entanglement detection in a pair of quarks, and also the entanglement observation at the highest energy scale so far. We show that entanglement can be observed by direct measurement of the angular separation between the leptons arising from the decay of the top–antitop pair. The detection can be achieved with high statistical significance, using the current data recorded during Run 2 at the LHC. In addition, we develop a simple protocol for the quantum tomography of the top–antitop pair. This experimental technique reconstructs the quantum state of the system, providing a new experimental tool to test theoretical predictions. Our work explicitly implements canonical experimental techniques in quantum information in a two-qubit high-energy system, paving the way to use high-energy colliders to also study quantum information aspects. PB Springer Nature SN 2190-5444 YR 2021 FD 2021-09-03 LK https://hdl.handle.net/20.500.14352/4717 UL https://hdl.handle.net/20.500.14352/4717 LA eng NO CRUE-CSIC (Acuerdos Transformativos 2021) NO Ministerio de Economía y Competitividad (MINECO) DS Docta Complutense RD 14 may 2024