Photonic Heat Rectification in a System of Coupled Qubits

We theoretically investigate a quantum heat diode based on two interacting flux qubits coupled to two heat baths. Rectification of heat currents is achieved by asymmetrically coupling the qubits to the reservoirs, which are modeled as dissipative RLC resonators. We find that the coherent interaction between the qubits can be exploited to enhance the rectification factor, which otherwise would be constrained by the temperatures and couplings of the baths. Remarkably high values of the rectification ratio, up to R~3.5, can be obtained for realistic system parameters, with an enhancement up to approximately 230% compared to the noninteracting case. The system features the possibility of manipulating both the rectification amplitude and direction, allowing for an enhancement or suppression of the heat flow to a chosen bath. For the parameter regime in which rectification is maximized, we find a significant increase of the rectification above a critical interaction value, which corresponds to the onset of a nonvanishing entanglement in the system. Finally, we discuss the dependence of the rectification factor on the bath temperatures and couplings.