Over de past decade, conventional superconductors (like Al), have been replaced by disordered superconductors (like beta-Ta, PtSi, Hf and TiN) in visible/near-infrared MKIDs, improving the responsivity and quantum efficiency. However, important detector characteristics, such as the single photon pulse decay time and generation-recombination (GR) noise levels, of disordered MKIDs are presently not understood.
We present temperature dependent GR noise and single photon (1545 – 402 nm) pulse measurements in MKIDs made from beta-Ta (Tc=1.0 K, ρ=240 μΩcm) and show that it does not follow theory. We hypothesize that quasiparticle trapping causes this deviation.
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