Observation of quantum entanglement with top quarks at the ATLAS detector
Entanglement is a key feature of quantum mechanics1-3, with applications in fields such as metrology, cryptography, quantum information and quantum computation4-8. It has been observed in a wide variety of systems and length scales, ranging from the microscopic9-13 to the macroscopic14-16. However,...
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| Main Authors: | , , , , , , , , , , , , , , , , , , , , , |
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| Format: | Article (Journal) |
| Language: | English |
| Published: |
18 September 2024
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| In: |
Nature
Year: 2024, Volume: 633, Issue: 8030, Pages: 542-547 |
| ISSN: | 1476-4687 |
| DOI: | 10.1038/s41586-024-07824-z |
| Online Access: | Verlag, kostenfrei, Volltext: https://doi.org/10.1038/s41586-024-07824-z Verlag, kostenfrei, Volltext: https://www.nature.com/articles/s41586-024-07824-z 
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| Author Notes: | The ATLAS Collaboration* |
| Summary: | Entanglement is a key feature of quantum mechanics1-3, with applications in fields such as metrology, cryptography, quantum information and quantum computation4-8. It has been observed in a wide variety of systems and length scales, ranging from the microscopic9-13 to the macroscopic14-16. However, entanglement remains largely unexplored at the highest accessible energy scales. Here we report the highest-energy observation of entanglement, in top-antitop quark events produced at the Large Hadron Collider, using a proton-proton collision dataset with a centre-of-mass energy of √s = 13 TeV and an integrated luminosity of 140 inverse femtobarns (fb)−1 recorded with the ATLAS experiment. Spin entanglement is detected from the measurement of a single observable D, inferred from the angle between the charged leptons in their parent top- and antitop-quark rest frames. The observable is measured in a narrow interval around the top-antitop quark production threshold, at which the entanglement detection is expected to be significant. It is reported in a fiducial phase space defined with stable particles to minimize the uncertainties that stem from the limitations of the Monte Carlo event generators and the parton shower model in modelling top-quark pair production. The entanglement marker is measured to be D = −0.537 ± 0.002 (stat.) ± 0.019 (syst.) for $$340\,{\rm{GeV}} < {m}_{t\bar{t}} < 380\,{\rm{GeV}}$$. The observed result is more than five standard deviations from a scenario without entanglement and hence constitutes the first observation of entanglement in a pair of quarks and the highest-energy observation of entanglement so far. |
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| Item Description: | *The ATLAS Collaboration: G. Aad, L.M. Baltes, F. Bartels, M.M. Czurylo, S.J. Dittmeier, M. Dunford, S. Franchino, T. Junkermann, M. Klassen, T. Mkrtchyan, P.S. Ott, D.F. Rassloff, S. Rodriguez Bosca, C. Sauer, A. Schoening, H.-C. Schultz-Coulon, V. Sothilingam, R. Stamen, P. Starovoitov, L. Vigani, S.M. Weber, M. Wessels, J. Zinsser [und sehr viele weitere Personen] Gesehen am 07.08.2025 |
| Physical Description: | Online Resource |
| ISSN: | 1476-4687 |
| DOI: | 10.1038/s41586-024-07824-z |