Entanglement and quantum tomography with top quarks at the LHC

• Published in: European physical journal plus Vol. 136; no. 9; p. 907
• Main Authors: Afik, Yoav, de Nova, Juan Ramón Muñoz
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 03.09.2021; Springer Nature B.V
• Subjects: Applied and Technical Physics; Atomic; Complex Systems; Condensed Matter Physics; Energy; High energy physics; Hilbert space; Large Hadron Collider; Leptons; Mathematical and Computational Physics; Molecular; Optical and Plasma Physics; Particle physics; Physics; Physics and Astronomy; Quantum entanglement; Quantum field theory; Quantum mechanics; Quantum phenomena; Quantum physics; Quarks; Qubits (quantum computing); Regular Article; Theoretical; Tomography
• ISSN: 2190-5444; 2190-5444
• DOI: 10.1140/epjp/s13360-021-01902-1

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.