Requirements on Photon Counting Detectors for Terahertz Interferometry

Abstract

Future Terahertz astronomy requires higher angular resolution observations. One possibility is to use photon counting interferometry, which is similar to the intensity interferometry demonstrated by Hanbury Brown and Twiss in 1956. In terahertz frequencies, it will be possible to measure all the photon arrivals and can identify bunched photons from thermal sources to measure correlation amplitude and time delay of the photon arrivals. By obtaining the complex visibility, aperture synthesis images can be obtained. I name this technology as photon counting terahertz interferometry (PCTI). From scientific case study, requirements to the detectors are high photon counting rate and accurate time resolution. I discuss on requirements on possible detector technologies such as superconducting single photon detectors (SSPD), superconducting tunnel junction (STJ) detectors and charge sensitive infrared phototransistors (CSIP).

Glauber theory and the quantum coherence of curvature inhomogeneities

“…Furthermore the idea suggested in Ref. [9] of applying the HBT interferometry to CMB photons has been taken seriously in [45,46]. According to these references it is not unconceivable that, in the future, bunched CMB photons could be identified and collected in the THz range.…”

Advantages of Photon Counting Detectors for Terahertz Astronomy

“…Statistics of photons can be a new tool for astronomy [11]. Thermal photons are governed by Bose-Einstein statistics and terahertz photons are often bunched as shown in Fig.…”

“…The idea of photon counting terahertz interferometry (PCTI) encourages the development of photon counting detectors for terahertz frequencies [11]. PCTI is an advanced version of the so-called Hanbury-Brown and Twiss intensity interferometry [14].…”

Towards a Graphene-Based Low Intensity Photon Counting Photodetector

“…Terahertz photodetection has been demonstrated using techniques such as bolometry [ 28 ], but many of these are at sub-THz frequencies. A technique using Photon Counting Terahertz Interferometry (PCTI) utilises the pulsed nature of photons at sub-far infrared frequencies, whereby detection on two or more telescopes can be used to measure the intensity correlation, enabling a wide bandwidth [ 29 , 30 , 31 , 32 ]. This technique requires detectors with a high count rate of 1–100 MHz and a time resolution better than 1 ps [ 31 ].…”

“…Varying this energy gap by means of graphene’s tuneable band-gap would enable potential operation at higher temperatures, overcoming cost and operational issues of cryogenic cooling. Scope also exists to exploit graphene to develop further high speed photodetectors for different photon energies with possibility for femtosecond photodetection [ 18 ], and to enable PCTI with smaller pixel sizes to allow for greater resolution resulting from a greater pixel density [ 29 , 30 , 31 , 32 ].…”