Mechanisms Causing Ballistic Thermal Rectification

The mechanism causing the ballistic thermal rectification in the harmonic system is analytically studied. Using the conceptual model of a dephasing probe, we obtain that phase breaking is unnecessary to realize the ballistic thermal rectification. However, it can change the strength of rectification. Asymmetric phonon-phonon interaction inducing the energy exchange of the normal mode of vibration is necessary to realize the ballistic thermal rectification. Moreover, the quantum statistics of phonons in at least one thermal reservoir is crucial to guarantee the asymmetric phonon-phonon interaction.