The effect of finite mass in cavity-QED calculations

The effect of finite nuclear mass is investigated in coupled light–matter systems in cavity quantum electrodynamics using the Pauli–Fierz Hamiltonian. Three different systems, the He atom, the H− ion, and the H2+ ion, are investigated. There are small but significant differences in the behavior of the binding energies as a function of coupling strength. The probability of coupling to light is found to be very small, but even this small coupling has a very strong effect on the energies of the systems.