  Engineering the coupling between fundamental quantum excitations is at the
heart of quantum science and technologies. A significant case is the creation
of quantum light sources in which coupling between single photons and phonons
can be controlled and harnessed to enable quantum information transduction.
Here, we report the deterministic creation of quantum emitters featuring highly
tunable coupling between excitons and phonons. The quantum emitters are formed
in strain-induced quantum dots created in homobilayer semiconductor WSe2. The
colocalization of quantum confined interlayer excitons and THz interlayer
breathing mode phonons, which directly modulate the exciton energy, leads to a
uniquely strong phonon coupling to single-photon emission. The single-photon
spectrum of interlayer exciton emission features a single-photon purity >83%
and multiple phonon replicas, each heralding the creation of a phonon Fock
state in the quantum emitter. Owing to the vertical dipole moment of the
interlayer exciton, the phonon-photon interaction is electrically tunable in a
wide range, promising to reach the strong coupling regime. Our result
demonstrates a new type of solid-state quantum excitonic-optomechanical system
at the atomic interface that emits flying photonic qubits coupled with
stationary phonons, which could be exploited for quantum transduction and
interconnection.
