Photon statistics as a tool for radio astronomy

Photon statistics can be a new tool for astronomical observations. In terahertz frequency region, thermal photons are often bunched which create larger intensity fluctuation than random fluctuation of photons. Measurements of the input photon statistics would tell us more than their intensity, such as the brightness temperature of sources as well as the time delay of intensity fluctuation using the bunched photon arrivals. By developing fast photon counting detector in terahertz frequencies using superconducting tunnel junction detectors, it will be possible to characterize terahertz emission sources and making use of them for photon counting terahertz interferometry (PCTI).