Testing The Universality Of Free Fall By Comparing The Atoms In Different Hyperfine States With Bragg Diffraction

We perform a precision atom interferometry experiment to test the universality of free fall. Our experiment employs the Bragg atom interferometer with Rb-87 atoms either in hyperfine state , and the wave packets in these two states are diffracted by one pair of Bragg beams alternatively, which is helpful for suppressing common-mode systematic errors. We obtain an Eotvos ratio eta 1-2=, and set a new record on the precision with improvement of nearly 5 times. This measurement also provides constraint on the difference of the diagonal terms of the mass-energy operator.