Fig. 1 SEM photos of a fabricated Ti TES and a TiN MKID
Researchers led by Prof. Sheng-Cai Shi, Purple Mountain Observatory, Chinese Academy of Sciences, are developing a THz superconducting imaging array (TeSIA) for the 5-meter THz telescope (DATE5) to be constructed at Dome A. We are currently developing TeSIA for DATE5 with a pixel number of 32x32 at 350 mm. Ti Transition edge sensors (TES) with time-domain multiplexing and TiN microwave kinetic inductance detectors (MKID) with frequency-domain multiplexing are both developed for the TeSIA.
We designed and fabricated Ti TESs with the microbridge length ranging from 1 to 6 mm. The current-voltage characteristics of the fabricated Ti TES are measured at different bath temperatures, from which the thermal conductance is found to be about 300 pW/K. The obtained electrical noise equivalent power is ~4x10-17W/Hz0.5, sufficiently low for TeSIA instrument. In addition, we have developed a 0.35THz 8x8 CPW MKID array based on TiN superconducting films with transition temperature of 4.5K. The measured Q factors of the MKIDs ranges from 10 to 100k, and the frequency shift with respect to the normalized bath temperature (T/Tc) follows a general trend predicted by the Mattis-Bardeen theory, but with a lowered roll-off.
The three works by Sheng-Cai Shi, Wen Zhang, Jing Li, Wei Miao, Zhen Wang, Zhen-Hui Lin, Zheng Lou, Qi-Jun Yao, et al, accepted by Journal of low temperature physics, have been published online