  We have recently reported the successful fabrication of bright single-photon
sources based on Ag-embedded nanocone structures that incorporate InAs quantum
dots. The source had a photon collection efficiency as high as 24.6%. Here we
show the results of various types of photonic characterizations of the
Ag-embedded nanocone structures that confirm their versatility as regards a
broad range of quantum optical applications. We measure the first-order
autocorrelation function to evaluate the coherence time of emitted photons, and
the second-order correlation function, which reveals the strong suppression of
multiple photon generation. The high indistinguishability of emitted photons is
shown by the Hong-Ou-Mandel-type two-photon interference. With quasi-resonant
excitation, coherent population flopping is demonstrated through Rabi
oscillations. Extremely high single-photon purity with a $g^{(2)}$(0) value of
0.008 is achieved with $\pi$-pulse quasi-resonant excitation.
