  The quantum nature of photonic systems is reflected in the photon statistics
of the light they emit. Therefore, the development of quantum optics tools with
single photon sensitivity and excellent temporal resolution is paramount to the
development of exotic sources, and is particularly challenging in the THz range
where photon energies approach kbT at T=300 K. Here, we report on the first
room temperature measurement of field g1({\tau}) and intensity correlations
g2({\tau}) in the THz range with sub-cycle temporal resolution (146 fs) over
the bandwidth 0.3-3 THz, based on electro-optic sampling. With this system, we
are able to measure the photon statistics at threshold of a THz Quantum Cascade
Laser.
