Speaker
Description
The two-photon collision option of a linear e+e− collider, a photon linear collider, is using the back-scattered laser photons off the incident electrons and positrons. The polarizations of the colliding photons can be controlled by using the polarized initial electrons and positrons and the polarized laser beams. We study the impact of the polarizations of the colliding photons on observation of quantum entanglement in top quark pair production at a photon linear collider. By use of the spin density matrix of a two-qubit system constructed from the amplitude level, we demonstrate that a photon linear collider is an ideal machine to probe quantum entanglement in the entire region of the phase space. We note that our formalism for the spin density matrix is largely process- and model-independent and helps to classify the polarization vectors and spin correlations of top quarks according to their P, CP, and CPT parities.