Quantum control of heat current

We study the steady-state, internal current circulation of local thermal currents in a bosonic trimer with a geometric phase inside it. Driven by two external reservoirs at different temperatures, the system exhibits a nonreciprocal current between two of its sites in thermal equilibrium, without violating the zeroth law of thermodynamics. Notably, our study explores both the limits where the internal hopping amplitude falls within weak- and strong-coupling regimes, relative to the system's dissipation rates. While nonreciprocity persists in the strong-coupling regime, we observe a novel phase reversal in the nonequilibrium current. We discuss its experimental feasibility and propose exciting new possibilities for implementing quantum-controlled heat devices.