  We suggest a novel source of polarization-entangled photon pairs based on a
cross-shaped plasmonic nanoantenna driven by a single quantum dot. The
integration of the nanoantenna with a metal mirror overcomes the fundamental
tradeoff between the spontaneous emission (SE) enhancement and the extraction
efficiency typical of microcavity and nanowire-based architectures. With a
very-high extraction efficiency of entangled photons (~90%) at 1.55 um and
large SE enhancement (~90) over a broad 330 nm spectral range, the proposed
design will pave the way toward reliable integrated sources of nonclassical
light.
