Effects of magnetic fields on the kinetic inductance detector arrays for the terahertz intensity mapper

Le résumé fourni par la source

Kinetic Inductance Detectors (KIDs) are superconducting micro-resonators used for radiation detection, with applications spanning astrophysics, cosmology, remote sensing, and quantum computing. Optimizing a KID array requires managing the internal quality factor (Qi) and minimizing frequency scatter: resonance frequency deviations of up to 1% from design values can reduce detector yield or disrupt the frequency-to-position correlation needed to reconstruct an array’s spatial map, while low Qi values reduce detector sensitivity and multiplexing. Both effects limit an array’s scientific capabilities. We present the impact of magnetic fields on Qi and resonance frequency in an array of lumped-element KIDs used in the Terahertz Intensity Mapper (TIM). We find that magnetic fields applied perpendicular to the detector plane during the superconducting transition produce a measurable resonance frequency shift and scatter, along with significant Qi degradation, while fields applied parallel to the detector plane have no measurable effect on either quantity. The perpendicular-field-induced frequency shift, however, is too small to account for the σ ∼ 5 × 10−4 frequency scatter we observe between cooldowns of the same array, allowing us to rule out varying magnetic fields as the dominant source of that scatter. We further find that the Qi degradation trends measured with our horn-coupled array match those previously reported for a non-optically-coupled detector geometry, indicating that the horn-coupled waveguide array does not change the detectors’ susceptibility to magnetic fields. These results inform the design of the TIM in-flight magnetic shielding and, more broadly, help optimize KID performance for diverse applications.

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