An ultra-low noise superconducting antenna-coupled microbolometer with a room-temperature read-out

In this letter, we report the electrical and optical characteristics of a superconducting vacuum-bridge microbolometer with an electrical noise equivalent power of 26 fW root Hz and an effective time constant of 380 ns, when operated at a bath temperature of 4 K. We employ a novel room temperature external negative feedback readout architecture, that allows for noise matching to the device without bulky stepup transformers or cooled electronics. Both the detector and the readout lend themselves to be scaled to imaging arrays. The directly measured noise equivalent temperature difference over a 100-1000-GHz bandwidth is 125 mK in a 30-ms integration time.