Lamb Shift Breaks the Heat Current Limit

We study the Lamb shift by considering the steady-state heat current through two coupled two-level atoms, which, respectively, interact with a heat reservoir at a certain temperature. It is found that the Lamb shift significantly alters the energy levels. In particular, it is shown that the heat current will approach an upper bound if the Lamb shift isn't considered, while the heat current will break the upper bound if the Lamb shift is considered. This finding can deepen our understanding of Lamb shift in the quantum thermodynamic field.