Origin of exceptionally low uncorrected frequency scatter

Determine how a frequency scatter as low as \(\sigma=4.7\times10^{-4}\) can be obtained without post-fabrication correction in microwave kinetic inductance detector arrays fabricated using the same electron-beam process, including whether specific detector designs provide greater resilience to fabrication-induced variations.

Background

The paper discusses frequency scatter as a principal limitation on the yield of densely multiplexed microwave kinetic inductance detector arrays. Fabrication-induced variations in resonator geometry and material properties typically produce frequency scatter in the range $\sigma=10^{-3}$ to $10^{-2}$, while post-fabrication trimming is generally required to reach values sufficiently low for high multiplexing factors.

A value of $\sigma=4.7\times10^{-4}$ had previously been reported without post-fabrication correction. The paper notes that the mechanism enabling this unusually low scatter is not understood, particularly because the authors use the same electron-beam fabrication process for their own arrays and obtain substantially larger scatter before trimming. Resolving this issue could clarify which resonator-design features or fabrication conditions suppress sensitivity to process variations.