  A two-level atom cannot emit more than one photon at a time. As early as the
1980s, this quantum feature was identified as a gateway to "single-photon
sources", where a regular excitation sequence would create a stream of light
particles with photon number fluctuations below the shot noise. Such an
intensity squeezed beam of light would be desirable for a range of applications
such as quantum imaging, sensing, enhanced precision measurements and
information processing. However, experimental realizations of these sources
have been hindered by large losses caused by low photon collection efficiencies
and photophysical shortcomings. By using a planar metallo-dielectric antenna
applied to an organic molecule, we demonstrate the most regular stream of
single photons reported to date. Measured intensity fluctuations reveal 2.2 dB
squeezing limited by our detection efficiency, equivalent to 6.2 dB intensity
squeezing right after the antenna.
