Testing the Universality of Free Fall by Comparing the Atoms in Different Hyperfine States with Bragg Diffraction*

Abstract

We perform a precision atom interferometry experiment to test the universality of free fall. Our experiment employs the Bragg atom interferometer with 87Rb atoms either in hyperfine state F = 1 , m F = 0 or F = 2 , m F = 0 , 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 Eötvös ratio η 1 − 2 = 0.9 ± 2.7 × 10 − 10 , 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.