Ingredients of thermal rectification: the case of classical and quantum self-consistent harmonic chains of oscillators.

In order to identify the ingredients of thermal rectification, we analytically investigate the heat flow in the asymmetric classical and quantum self-consistent harmonic chains of oscillators. We confirm the absence of rectification in the classical version of the model, and, for the quantum analog, we show that the combination of a local heat flow proportional to the temperature gradient and a local thermal conductivity dependent on parameters asymmetrically distributed in the chain and on the local temperature lead to thermal rectification. Some of these ingredients are provided by the quantum nature of the specific model analyzed here, but they are not restricted to quantum phenomena and can also appear in anharmonic classical models. The comprehension of such mechanism is important for the advance of phononics, since thermal rectifiers are the basic components of several devices proposed to control the heat flow.