SPT-SLIM and Fundamental Cosmology with Future Millimeter-Wave Line Intensity Mapping Experiments*

Line Intensity Mapping (LIM) at millimeter wavelengths is a promising method for measuring the large-scale structure of the Universe over a larger redshift range than traditional galaxy surveys. However, current-generation LIM instruments are not yet sensitive enough for competitive cosmological constraints. I will discuss future science cases enabled by LIM over wide redshift ranges, including constraining the expansion history and dark energy at high redshift, measuring the sum of neutrino masses, and constraining primordial non-Gaussianity. I will then present the South Pole Telescope Summertime Line Intensity Mapper (SPT-SLIM), a pathfinder instrument that will demonstrate key technologies necessary for improving the instantaneous sensitivity of mm-wave LIM experiments including high-density on-chip spectrometers and readout electronics. Finally I will discuss the sensitivity needed to cross critical thresholds in LIM science cases, and the stages of potential future instruments based on SPT-SLIM technology.