Topological Energy Transfer in an Optomechanical System with Exceptional Points

Exceptional points are topological singularities in the spectrum of an open system where complex eigenvalues of the underlying non-Hermitian Hamiltonian coalesce. We show the existence of an exceptional point in an optomechanical system composed of a suspended SiN membrane and a Fabry-Perot cavity in a cryostat. We realize topological energy transfer between two mechanical modes of the membrane by encircling the exceptional point. We also demonstrate the nonreciprocal behavior of the energy transfer.