  We investigate the generation of photon-phonon entangled states by exploiting
stimulated Brillouin scattering in nanoscale waveguides. The squeezing type
Hamiltonian that represents creation and annihilation of photon-phonon pairs is
obtained out of the multimode photon-phonon interaction Hamiltonian in the
presence of a pump field. The Bogoliubov eigenstates of the Hamiltonian, which
are a coherent mix of propagating photons and phonons, show squeezing
properties in the uncertainties of the collective quadrature operators. The
measurement of the photonic component can provide a controllable source of
single phonons in demand.
