Topological Quantum Thermocouple*

The flows of charge and heat in an open quantum system coupled to three macroscopic electron reservoirs are studied. It is shown that even without particle-hole asymmetry in the electronic structure, thermoelectric effects can be induced topologically by the Aharonov-Bohm effect. The Peltier effect is calculated, and the conditions of maximum cooling power are determined. The Carnot bound on the refrigeration coefficient is verified, and in so doing, a generalized relationship between the Peltier and Seebeck effects in multi-terminal quantum devices is derived. An apparent thermodynamic paradox involving persistent Peltier cooling in equilibrium is resolved by a rigorous treatment of heat flow at the quantum level.