We use a dual-species atom interferometer with 2 s of free-fall time to measure the relative
acceleration between Rb 85 and Rb 87 wave packets in the Earth's gravitational field.
Systematic errors arising from kinematic differences between the isotopes are suppressed
by calibrating the angles and frequencies of the interferometry beams. We find an Eötvös
parameter of η=[1.6±1.8 (stat)±3.4 (syst)]× 10-12, consistent with zero violation of the
equivalence principle. With a resolution of up to 1.4× 10-11 g per shot, we demonstrate a …

We use a dual-species atom interferometer with 2 s of free-fall time to measure the relative
acceleration between 85Rb and 87Rb wave packets in the Earth's gravitational field.
Systematic errors arising from kinematic differences between the isotopes are suppressed
by calibrating the angles and frequencies of the interferometry beams. We find an Eötvös
parameter of [1.6+/-1.8 (stat)+/-3.4 (syst)] x 10^-12, consistent with zero violation of the
equivalence principle. With a resolution of up to 1.4 x 10^-11 g per shot, we demonstrate the …