Exploring Q-scatter in kinetic inductance detectors
M.P.W. Herman (TU Delft - Applied Sciences)
W.G. Ras – Mentor (TU Delft - Tera-Hertz Sensing)
Jochem Baselmans – Graduation committee member (TU Delft - Tera-Hertz Sensing)
P. J. Visser – Graduation committee member (TU Delft - Tera-Hertz Sensing)
I. Esmaeil Zadeh – Mentor (TU Delft - ImPhys/Esmaeil Zadeh group)
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Abstract
Superconducting kinetic inductance detectors will play an important role in the future of exoplanet spectroscopy. Their low bandgap and the possibillity that they can be multiplexed into large arrays open up new opportunities where conventional semiconductors stop. A key requirement for the performance of these new detectors is the consistency of their quality factor (Q-factor). Variations in Q-factors, known as Q-scatter, result in nonuniform sensitivity and hold back scaling to larger systems.
In this thesis, detectors that differ in fabrication, pixel count and pixel spacing are analyzed and compared to find out what is the cause of Q-scatter. Possible causes include design errors, inaccurate fabrication, electromagnetic crosstalk, magnetic vortices and unbalanced transmission lines. Analysis showed Q-scatter is unlikely to be impacted by design, fabrication method, electromagnetic coupling or vortex forming. Also, no spatial relations, that indicated any transmission line effects, were observed. What is interesting however, is that the Q-factors of one of the chips seem to scatter all over again when measuring the chip again after trimming one of its components.
With the data available in this experiment it was not possible to give an concrete cause of Q-scatter. Furhter experiments, especially concerning the new scattering need to be conducted. Also, simulations using Sonnet v19 can give more insights in the origin of Q-scatter.