On-chip quantum phonodynamics

Sound can be just as quantum as light. But our toolbox for single quanta of sound, i.e. phonons, is currently insufficient. Here we describe a new component that enables a chip-based, solid-state analogue of cavity-QED utilizing acoustic phonons instead of photons, phonitons instead of polaritons. We show how long-lived and tunable acceptor (hole) impurity states in silicon nanomechanical cavities can play the role of a matter non-linearity for coherent phonons just as, for example, the Josephson qubit plays in circuit-QED. This system enables the control of single phonons and phonon-phonon interactions, dispersive phonon readout of the acceptor qubit, and compatibility with other nano/optomechanical components such as phonon-photon translators. Phonons, due to their unique properties, enable new opportunities for quantum devices and physics.