Coupling properties of subjects in a three-body interaction system with an intermediary entity and symmetrical participants on both sides

This paper studies the phenomenon of light-excited entanglement between nucleon spins, which is realized by using a transient light beam to excite the spin of electrons to produce entanglement between the two nucleon spins. This standard three-body interaction system is composed of an intermedium equivalent to a spin-1 quasiparticle and two spin-1/2 nucleons. We describe the entire system, its corresponding effective Hamiltonian, and the eigenvalues and eigenstates. The Hamiltonian is analyzed under the symmetric assumption, which can significantly simplify the effective Hamiltonian and make obtaining the corresponding dynamic characteristics easier. In the calculation process, degenerate perturbation theory calculates the eigenequation, whose degeneracy is not eliminated to a first approximation. We calculate the eigenequation to the second order to obtain an accurate zero-order wave function. •The phenomenon of light-excited entanglement between nucleon spins is studied.•The system with Hamiltonian, the eigenvalues and eigenstates is described.•The eigenequation to obtain an accurate zero-order wave function is calculated.