A measurement of gravitational lensing of the cosmic microwave background using SPT-3G

The cosmic microwave background (CMB) provides a method to map the universe's matter through gravitational lensing deflections as the CMB photons travel through the large-scale structures of the universe. Gravitational lensing induces correlations between CMB temperature and polarization modes at different angular scales. These correlations can be extracted by lensing quadratic estimators to reconstruct the projected 2D lensing potential and matter distribution. The power spectrum of the lensing potential is a powerful probe of the growth of structure and can constrain the sum of neutrino masses, dark energy, and the amplitude of matter density fluctuations. Furthermore, the matter distribution from lensing provides a promising source for cross-correlation with surveys at other wavelengths and offers a template for removing lensing-induced contamination in searches for inflationary gravitational waves. The third-generation camera for the South Pole Telescope (SPT-3G) is an excellent instrument for CMB lensing measurements with one arcminute resolution and high sensitivity powered by a ten-meter primary mirror and a new multichroic receiver with 16,000 polarization-sensitive detectors. Here I review the SPT-3G instrument and present measurements of the lensing potential and lensing power spectrum from the 2018 data of the SPT-3G survey.