A quasi-mode theory of chiral phonons
This paper (https://arxiv.org/abs/1612.09240) provides theoretical support for the previous experimental work (https://arxiv.org/abs/1609.08674) on the observation of chiral phonon transport and cooling in optomechanical systems. The main idea is that lossy bulk mechanical modes can be described by a quasi-mode picture, thus a continuum theory is effectively reduced to two-mode theory. After working out the optomechanical coupling rate, the mode scattering strength and the dissipation rate, we are able to solve the dynamics of this four-mode system under certain assumptions. We predict the simultaneous cooling and linewidth reduction behavior for counterpropagating phonons. We also try to fit the measured linewidth and power with theoretical predictions and give rough estimates of the relevant parameters for the system.