Optoacoustic Entanglement in a Continuous Brillouin-active Solid State System

Entanglement in hybrid quantum systems comprised of fundamentally differentdegrees of freedom, such as light and mechanics is of interest for a wide rangeof applications in quantum technologies. Here, we propose to engineer bipartiteentanglement between traveling acoustic phonons in a Brillouin active solidstate system and the accompanying light wave. The effect is achieved byapplying optical pump pulses to state-of-the-art waveguides, exciting aBrillouin Stokes process. This pulsed approach, in a system operating in aregime orthogonal to standard optomechanical setups, allows for the generationof entangled photon-phonon pairs, resilient to thermal fluctuations. We proposean experimental platform where readout of the optoacoustics entanglement isdone by the simultaneous detection of Stokes and Anti-Stokes photons in atwo-pump configuration. The proposed mechanism presents an important feature inthat it does not require initial preparation of the quantum ground state of thephonon mode.