On-Sky Demonstration of SPT-SLIM and SuperSpec: Superconducting Millimeter-Wave Spectrometers for Cosmology and Astrophysics

Spectroscopy at millimeter wavelengths is sensitive to far-infrared emission lines from high-redshift dusty galaxies that are often optically faint. Next-generation surveys have the potential to push measurements of large-scale structure to the first billion years of the universe, providing unprecedented constraints on the dynamics of reionization and the physics of inflation, dark energy, and dark matter. Recent advances in superconducting quantum detector technology have enabled an order-of-magnitude decrease in spectrometer size, and we can now envision large arrays of spectrometers-on-a-chip with the sensitivity for these science goals. I will present SPT-SLIM and SuperSpec, on-chip filter-bank spectrometers using kinetic inductance detectors. Both projects saw first light in 2025 - SPT-SLIM at the South Pole Telescope and SuperSpec at the Large Millimeter Telescope. I will discuss preliminary observations of astronomical objects, our understanding of device performance on sky, and future steps towards large, background-limited arrays.