MgB2 thermal kinetic inductance detector

Thermal Kinetic Inductance Detectors (TKIDs) inherently combine the phonon-limited noise performance of traditional bolometers with the array scalability and responsivity of superconducting kinetic inductance detectors. Using a superconducting resonator as the thermally sensitive element provides high responsivity and a tunable dynamic range, with phonon noise set by the cryogenic operating temperature of the free-standing membrane. In this work, MgB2-based TKIDs are demonstrated operating from below 1 K up to 20 K with characterized noise-equivalent power using integrated on-membrane heaters. A comprehensive characterization of electrical, thermal, and noise properties is presented. The internal quality factor of the prototype devices is measured to be Qi>2×104 at 4.2 K, with a bolometer time constant of τ<0.7 ms below 5.6 K. The intrinsic detector noise is NEPmeasured<10−14 W/Hz for T<8 K, demonstrating phonon noise-limited performance from 4 to 8 K.