Development of Multi-Chroic MKIDs for Next-Generation CMB Polarization Studies

TL;DR

This paper discusses the development and testing of multi-chroic MKID arrays designed for advanced CMB and Galactic dust polarization studies, demonstrating promising prototype results and plans for scaling up.

Contribution

It introduces a new design for multi-chroic MKID arrays with high multiplexing and fabrication yield, suitable for large-scale CMB polarization experiments.

Findings

Achieved a multiplexing factor of 92 in prototype arrays

Demonstrated MKID response to millimeter-wave pulses

Fabrication yield of 100% in initial arrays

Abstract

We report on the status of an ongoing effort to develop arrays of horn-coupled, polarization-sensitive microwave kinetic inductance detectors (MKIDs) that are each sensitive to two spectral bands between 125 and 280 GHz. These multi-chroic MKID arrays are tailored for next-generation, large-detector-count experiments that are being designed to simultaneously characterize the polarization properties of both the cosmic microwave background (CMB) and Galactic dust emission. We present our device design and describe laboratory-based measurement results from two 23-element prototype arrays. From dark measurements of our first engineering array we demonstrated a multiplexing factor of 92, showed the resonators respond to bath temperature changes as expected, and found that the fabrication yield was 100%. From our first optically loaded array we found the MKIDs respond to millimeter-wave pulses, additional optical characterization measurements are ongoing. We end by discussing our plans for scaling up this technology to kilo-pixel arrays over the next two years.