Kondo signature in heat transfer via a local two-state system.

We study the Kondo effect in heat transport via a local two-state system. This system is described by the spin-boson Hamiltonian with Ohmic dissipation, which can be mapped onto the Kondo model with anisotropic exchange coupling. We calculate thermal conductance by the Monte Carlo method based on the exact formula. Thermal conductance has a scaling form κ=(k(B)(2)T(K)/ħ)f(α,T/T(K)), where T(K) and α indicate the Kondo temperature and dimensionless coupling strength, respectively. Temperature dependence of conductance is classified by the Kondo temperature as κ is proportional to (T/T(K))(3) for T<<T(K) and κ is proportional to (kB)T/ħω(c))(2α-1) for T>>T(K). Similarities to the Kondo signature in electric transport are discussed.