Seminar: Alba Cervera Lierta [Barcelona Supercomputing Centre]: “Quantum Information as a Guiding Principle (and a Tool) for Fundamental Interactions”

Title: “Quantum Information as a Guiding Principle (and a Tool) for Fundamental Interactions”

Speaker: Alba Cervera Lierta [Barcelona Supercomputing Centre]

Venue & Time: Red Room | 15:00-16:00

Abstract: The interactions of the Standard Model are usually presented as consequences of gauge symmetry. In this talk I explore a complementary viewpoint: fundamental interactions are quantum, and the S-matrix generates quantum-information resources, such as entanglement or “magic” (non-stabilizerness), among the particles it scatters. I show that in tree-level QED, electroweak, QCD and perturbative gravity processes, requiring these resources to be extremal is enough to recover gauge and diffeomorphism invariance, and to provide a bound on the weak mixing angle, suggesting quantum information may act as a guiding principle behind the couplings we observe.
I then turn the argument around: can these same quantities serve as a tool? Colliders have become genuine quantum-information laboratories (entanglement and magic in top-quark pairs are now measured at the LHC) and I discuss how such observables probe physics beyond the Standard Model. As a concrete example, I present a new collider observable built from the spin density matrix of the top-antitop system, designed to search for invisible particles produced alongside a top-quark pair, and show it outperforms standard rate- and kinematics-based searches.