Diciembre 13, 2023
11:00 am
Time vs. Reality: entanglement in particle physics
Where and when
Date
Diciembre 13, 2023
11:00 am
Location
University of Valencia Science Park Seminar Room SS6
Featured speakers
José Bernabéu Alberola
Department of Theoretical Physics, University of Valencia. Member of the Spanish Royal Academy of Science.
Read bio
José Bernabéu Alberola is a Spanish physicist and full-professor specialized in particle physics, with special emphasis on his research on the unification of electroweak interactions. Born in the Alicante municipality of Mutxamel, in 1967 he graduated from the University of Valencia. In 1970 he obtained his PhD in Physics. From 1971 to 1978 he worked at CERN, in Switzerland, being the first Spaniard to join the staff of the Theoretical Physics Division. In 1976 he obtained the position of Associate Professor at the University of Barcelona, and the following year at the University of Valencia, but his teaching career has been developed in various universities around the world such as Louvain-la-Neuve, Bergen, Lyon, La Plata, Oviedo and Paris-Orsay. In 2008 he received the Jaume I Award for Basic Research, and in 2011 he was awarded the Physics Medal of the Spanish Royal Society of Physics. Author of numerous research papers, he has held positions of responsibility in several Spanish and international scientific councils.
Entanglement in particle anti-particle systems, like K0-K0bar and B0-B0bar in charge conjugation C = -, offers several novelties not present in other fields. This includes the mixing between the partners, charge-parity CP violation – either in the mixing, the interference between mixing and decay or the decay- and above all a non-trivial time evolution of the system. Besides the study of the time history of the system since the production to its fate, with the tag of the living partner and the quantum filtering of the first-decayed state, a way to inquire into the states at entanglement times t1 before the first decay appears.
A novel surviving quantum correlation-in-time emerges from the observation of the second decay at time t2 > t1, when the system is no longer entangled, to the post-tag of the past-decayed state before its decay when the system was entangled. The two correlations, from past to future and from future to past, are asymmetric and the second adds the surprising result that the past-decayed state depends on the future observation time t2. This dependence is fully observable from the t1-distribution of events for two identical observations at distinct times t2 and can be quantified for the K0-K0bar system, where the KLOE-2 collaboration at DAPHNE has presented preliminary results. Neither in classical nor in quantum mechanics time is an observable, it is a parameter describing the definite evolving reality. Past states depending on future observation times call for a novel role of time in quantum mechanics and establish a lack of instant realism.
The two correlations are most rewarding as a tool to bypass existing no-go arguments for single unstable particles. I shall first discuss the conceptual basis for a direct test of Time Reversal – and CPT – in the Delta t = t2-t1 evolution of the living partner in the B0-B0bar system. The observation of Time-Reversal-Violation by the BABAR experiment followed these ideas. An asymmetry «independent of the decay products» allows the reversal of meson states in Delta t. CP violation and the non-orthogonality of the KS,L states of definite time evolution in the K0-K0bar system preclude their tag on an event-by-event basis. The novel correlation-in-time from future to past establishes for the first time (after 60 years of rare KL decays) the condition to tag a KS-beam with any desired purity. This fact opens an entirely new field in particle physics.
