A superconductor–insulator–normal metal bolometer with microwave readout suitable for large-format arrays

Abstract

We demonstrate high bandwidth and low-noise readout of a superconductor–insulator–normal metal–insulator–superconductor hot-electron bolometer element. We measure a noise equivalent temperature of better than $0.6\mu \mathrm{K}∕{\mathrm{Hz}}^{1∕2}$ and infer an electrical noise equivalent power of $7\times {10}^{-17}\mathrm{W}∕{\mathrm{Hz}}^{1∕2}$ for a normal-metal volume of $4.5\mu {\mathrm{m}}^3$ at an operating temperature of $270\mathrm{mK}$ . Using a pulsed bias technique we measure a thermal time constant of $1.2\mu \mathrm{s}$ at $270\mathrm{mK}$ . The microwave readout method we employ is compatible with large-format arrays of ${10}^3–{10}^5\text{pixels}$ required by future far-infrared space and ground-based observatories.