Scientists have demonstrated that the Bethe-Heitler process, a fundamental interaction in particle physics, can be utilized as a laboratory to generate and study multiparticle quantum entanglement. This work transforms a known process of photon radiation by an electron scattering off a proton ($e+p\to e+p+\gamma$) into a platform for investigating complex quantum states.

The research focused on how bipartite and genuine tripartite entanglement is built up between the final state electron, proton, and photon resulting from the interaction. This entanglement emerges through a series of elementary $1\to 2$ and $2\to 2$ interactions. The results, validated by event simulations, reveal the formation of specific entangled quantum states.

Below a center-of-mass energy of 5 GeV, simulations identified more than 900 Greenberger-Horne-Zeilinger (GHZ) states and 1200 W states. The fidelity of these states exceeded 99%, indicating high quality of the generated entanglement. This finding is significant as it opens a new avenue for exploring quantum entanglement in a high-energy physics context, traditionally associated with particle production and the study of fundamental forces.