Studies of non-Hermitian physics have revealed new possibilities to manipulate wave scattering on lossy materials. For example, all-light control can be achieved based on the Coherent Perfect Absorption (CPA) effect. On the other hand, controlling heat transfer may confer a distinct paradigm other than the use of thermal metamaterials. However, since heat is not directional, almost all concepts in wave scattering are ill-defined for steady-state thermal diffusion and it is difficult to understand or utilize any coherent effect.

In May 2022, Prof. CHEN Hongsheng and Prof. LI Ying of ISEE, Prof. QIU Chengwei of National University of Singapore, and Prof. ZHU Xuefeng of Huazhong University of Science and Technology, co-published an article entitled “Heat Transfer Control Using a thermal analogue of Coherent Perfect Absorption” in Nature Communications. 

In this work, the research team established the thermal diffusion scattering theory by introducing an imitated momentum for thermal fields, and discovered the thermal analogue of CPA. Unlike its photonics counterpart, thermal CPA can achieve thermally transparent using regular materials by selecting the right heat input. The theory offers great flexibility in heat transfer control and is expected to stimulate wider research on diffusion processes.

Figure 1: Correspondence between one-dimensional electromagnetic scattering and two-dimensional steady thermal diffusion

Figure 2: Experimental demonstration of thermal Coherent Perfect Absorption (CPA) 

This work is supported by the National Natural Science Foundation of China, the Fundamental Research Funds for the Central Universities, and the Ministry of Education of Singapore.

The article link: https://www.nature.com/articles/s41467-022-30023-1