Testing the Universality of Free Fall at ${10^{ - 10}}$ level by Comparing the Atoms in Different Hyperfine States with Bragg Diffraction

TL;DR

This paper reports a high-precision test of the universality of free fall using atom interferometry with rubidium atoms in different hyperfine states, achieving a new record precision of 10^{-10}.

Contribution

The study introduces a novel experimental approach employing Bragg atom interferometry with hyperfine states to test UFF, significantly improving measurement precision and constraining potential UFF violations.

Findings

Measured Eötvös ratio η = (0.9 ± 2.7) × 10^{-10}

Achieved nearly fivefold improvement in precision over previous tests

Set new limits on UFF breaking mechanisms

Abstract

We have performed a precision atomic interferometry experiment on testing the universality of free fall (UFF) considering atoms' spin degree of freedom. Our experiment employs the Bragg atom interferometer with $^{87}$Rb atoms either in hyperfine state $\left| {F = 1,{m_F} = 0} \right\rangle $ or $\left| {F = 2,{m_F} = 0} \right\rangle $, and the wave packets in these two states are diffracted in one pair of Bragg beams alternatively, which can help suppress the common-mode systematic errors. We have obtained an E$\rm{\ddot{o}}$tv$\rm{\ddot{o}}$s ratio $\eta = \left( { 0.9 \pm 2.7} \right) \times {10^{ - 10}}$, and set a new record on the precision with a nearly 5 times improvement. Our experiment gives stronger restrictions on the possible UFF breaking mechanism.