Controlling thermal fluctuation of phonon modes with nonreciprocal dynamics in an optomechanical system

Nonreciprocal dynamics in optomechanical systems is of rising interest in the past several years. While earlier works mainly focused on photonic modes, here we study nonreciprocal dynamics for phonon modes. We have realized nonreciprocal coupling between phonon modes, which leads to nonreciprocal phonon transfer. We achieved phonon isolation which can be tuned continuously over a wide range from -30dB to 30dB. We show the nonreciprocal phonon transfer as a new way to control the thermal fluctuation of phonon modes by controlling laser phases.