Superconducting quantum detectors

Abstract:

We present the design of planar superconducting on/off switch comprising a number of high normal resistance nano-bridges deposited across a the slot of a unilateral finline. We have simulated the performance of this device and have shown that it has a much larger dynamic range than a single nano-bridge fabricated from the same material (Niobium Nitride, NbN). The response of a single bridge device was measured either directly using a terahertz power meter or by using superconductor-insulator-superconductor (SIS) device as direct detector. In either method, we have demonstrated good agreement between simulations and measurements, and therefore confirmed the integrity of our analysis of the device performance. We have recently designed and fabricated multiple nano-bridges superconducting switches using 50 µm thick NbN film. The measurement of these devices is currently in progress and we expect to report the results in the forthcoming ISSTT conference in March.

Abstract:

We describe near-field tests and results of an 8 pixel close-packed feedhorn array that will be a key component of an 8 pixel prototype 350 GHz SIS mixer array receiver prototype under construction at SAO. We have fabricated an array of smooth walled multiple flare angle feedhorns by direct drilling into a single block of aluminum. Testing of the feedhorns was carried out using a nearfield scanner and a vector network analyzer based on custom built transmitters and receivers and an HP vector voltmeter. The vector nearfield data is transformed to the farfield radiation pattern using Python code based on the NF2FF Matlab script[1].