Cosmic entanglement sudden birth: expansion-induced entanglement in hydrogen atoms

In our analysis of the expansion-induced hyperfine entanglement of the hydrogen atom, we use the standard Hamiltonian for the hyperfine structure of the ground-state atomic hydrogen. This involves introducing the electron spin operator \(\hat{S}\) and the proton spin operator \(\hat{I}\). Therefore, the effective Hamiltonian for the ground-state hyperfine structure can be expressed as \({H}_{HF}=A\hat{S}\cdot \hat{I}\). … Read more