Optical cooling of mirrors to nearly absolute zero can help eliminate measurement noise arising from thermal vibrations. Part of Mavalvala's work focused on the extension of laser-cooling techniques to optically cool and trap more and more massive objects, both for the LIGO project and for other applications, such as to enable observation of quantum phenomena in macroscopic objects. Prominent results from her group in this area included cooling of a centimeter-scale object to a temperature of 0.8 kelvins and observation of a 2.7-kilogram pendulum near its quantum ground state.