Prof. Liu's research focuses on symmetry tests and fundamental neutron physic to understand matter creation and nucleosynthesis in the early Universe. She specializes in experimental tools using Ultra-Cold Neutrons (UCN). In her dissertation work, she solved the critical issue of excessive loss of UCN due to upscattering by para-D2 molecules in solid D2 and made the world's first working solid deuterium source for UCN production. This breakthrough prompted the investments of several multi-million dollar UCN facilities around the world, including the Los Alamos National Laboratory, the PULSTAR reactor at the North Carolina State University, the TRIGA reactor at Mainz University in Germany, and the Paul Scherrer Institut in Switzerland. She studied the magnetic excitations in cryogenic oxygen solids for UCN production in the Lujan Center of Neutron Scattering. In 2011--2016, she led the UCNtau experiment, as a co-spokesperson; the experiment now holds the record of the most precise measurement of the neutron lifetime. In 2018, Liu won an NSF Major Research Instrumentation grant to construct a room-temperature apparatus for improving the measurement of the neutron electric dipole moment.