Investigation of high-sensitivity superconducting HEB mixers for Antarctic astronomy

Therese Berg

Kangmin Zhou

China is now building an astronomical observatory including a THz telescope at Dome A on the Antarctic plateau. The development of superconducting HEB (Hot Electron Bolometer) mixers, the best choice for coherent detection at frequencies beyond 1 THz, becomes increasingly crucial. We present in this manuscript the investigation of high-sensitivity superconducting HEB mixers using quasi-optical technology in the THz region. The main results of this study are as follows: 1. We measured the dielectric constant of high-resistivity silicon at 77 K and 295 K by a vector measurement system. The measured permittivity is adopted to simulate the far-field beam pattern of a quasi-optical superconducting HEB mixer. 2. We measured the far-field beam pattern of a superconducting HEB mixer by both near-field heterodyne measurement system and far-field direct detection measurement system. The measured results accord well with the simulation. We also investigated the effect of HEB bias voltages and bath temperature on the far-field beam-pattern. 3. We successfully developed a high-sensitivity superconducting HEB mixer at 1.3 THz. The uncorrected measured double-sideband noise temperature is 600 K, which is a state-of-the-art result at this frequency. We systematically characterized heterodyne performances such as RF noise, conversion gain and noise bandwidth. We also measured the frequency response and calibrated it with a new method. Furthermore, we investigated the performance of this superconducting HEB mixer integrated with different elliptical lenses. 4. Finally, we measured the noise performance and the frequency response of a HEB mixer coupled to a 0.1-1.5 THz spiral antenna, the frequency dependence of the noise temperature has also been characterized. This study has provided a further understanding of superconducting HEB mixers and allowed the realization of a HEB mixer with state-of-the-art sensitivity at 1.3 THz. Hence the results of this study can find good use in the 5 m terahertz telescope (DATE5) at Dome A.

Jinping Wang, YangBin Li, Lin Kang +7 more

Sheng‐Cai Shi

With outstanding sensitivity, superconducting mixers and detectors play an increasingly important role in mm- and submm-wave (a.k.a. THz) astronomy. Firstly, a newly developed 3×3 superconducting array receiver for the 0.1-THz band will be introduced. Secondly, a 0.5-THz receiver using high-energy-gap NbN superconducting tunnel junctions will be presented. Thirdly, the latest development of China's THz project at Dome A, Antarctic, will be addressed.

Sheng‐Cai Shi

Sheng-Cai Shi

The MM and SubMM Lab of Purple Mountain Observatory has made major efforts in the development of high-sensitivity detectors for radio astronomy. The paper mainly introduces the development of a 500-GHz superconducting SIS (superconductor-insulator-superconductor) mixer and an 850-GHz HEB (hot-electron-bolometer) mixer.