Dual Effects of Lamb Shift in Quantum Thermodynamical Systems.

The Lamb shift, as an additional energy correction induced by environments usually, has a marginal contribution and hence is neglected. We demonstrate that the Lamb shift, which modifies the energy levels, can influence the heat current to varying extents. We focus on the steady-state heat current through two coupled two-level atoms, respectively, in contact with a heat reservoir at a certain temperature. We find that the Lamb shift suppresses the steady-state heat current at small temperature gradients, while at large gradients, the heat current is restricted by an upper bound without the Lamb shift but diverges when it is included. These results not only demonstrate the Lamb shift's critical role in quantum heat transport but also advance our understanding of its impact in quantum thermodynamics.