Non-Hermitian Casimir effect of magnons

Nakata, Koki   

Recently, non-Hermitian quantum mechanics has been attracting considerable attention. The key concepts of quantum mechanics are quantum fluctuations. Quantum fluctuations of quantum fields confined in a finite-size system induce the zero-point energy shift. This quantum phenomenon, the Casimir effect, is one of the most striking phenomena of quantum mechanics in the sense that there are no classical analogs and has been drawing much attention from various research areas, including high energy physics, beyond the hierarchy of energy scales. However, the non-Hermitian extension of the Casimir effect and the application to spintronics remain missing ingredients. Here we fill this gap. By developing a magnonic analog of the Casimir effect into non-Hermitian systems, we show that energy dissipation serves as a key ingredient of Casimir engineering to control and manipulate the Casimir effect of magnons.