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Application of intensity interferometry in far-infrared and terahertz frequencies is discussed for high angular resolution observations. Interferometer technologies with heterodyne and double Fourier are compared to clarify the merit of intensity interferometry and challenges to aperture synthesis imaging. Photon bunching caused by thermal radiation can be used to determine the delay time in place of electromagnetic phase information, which may estimate the complex visibility for aperture synthesis imaging. For the fast measurement of photon bunching, superconducting tunnel junction detectors, such as SIS photon detectors, can be used. Laboratory demonstrator of intensity interferometry was developed using a 4-K pulse-tube cooler, 4He sorption fridges, and SIS photon detectors with fast readout electronics. Optical evaluation of the detector performance as well as developments of fast readout electronics are made toward intensity correlation and delay time measurements. Applications to long baseline terahertz interferometry in Antarctica and to space far-infrared interferometry are discussed.
Matsuo et al. (Wed,) studied this question.