Spin Correlation and Quantum Entanglement of Fermion Pairs in Transversely Polarized $e^-e^+$ Collisions

TL;DR

This paper investigates how transversely polarized electron-positron collisions produce maximally entangled fermion pairs, revealing the potential to control quantum entanglement in collider experiments for quantum information applications.

Contribution

It demonstrates that transverse polarization enhances and controls spin entanglement in various electron-positron scattering processes, including QED and electroweak interactions.

Findings

Maximal entanglement occurs in $e^-e^+ o far f$ with transverse polarization.

Entanglement varies across phase space points depending on the process.

Transverse polarization significantly enhances final state entanglement.

Abstract

We systematically study the spin correlations and quantum entanglement in transversely polarized electron-positron collisions. We find that the $s$-channel QED process $e^-e^+\to f\bar f$ produces a maximally entangled state in the entire phase space when the initial beams are transversely polarized, while the quantum magic varies in different phase space points for the maximally entangled Bell states. For electroweak processes, the spin configuration of final states depends on chiral couplings, and the entanglement is also greatly enhanced by transverse polarization as in the QED process. For Bhabha scattering with additional $t$-channel contributions, the transverse polarization still increases the final state entanglement, although with some dilution. The sensitive dependence of final spin states on the transverse polarization makes the beam polarization a powerful tool for generating and controlling quantum entanglement in collider experiments, opening up new opportunities for quantum information studies at high-energy colliders.