Test of weak equivalence principle of microscopic particles based on atom interferometers

Abstract

The equivalence principle is one of the two basic assumptions of general relativity. It is the extension of weak equivalence principle. At present, a lot of experiments have tested the weak equivalence principle within a certain accuracy. However, the new theories that unify the gravity and the standard model require the weak equivalence principle to be broken, so the highly accurate test of the weak equivalence principle has important scientific significance. The test of the weak equivalence principle using microscopic particles complements and extends that using macroscopic objects. In this paper, the principle of the atomic interferometer is introduced, and the history and status quo of experimental study on weak equivalence principle of microscopic particles using atomic interferometer are reviewed. The precision of experiments using different-mass atoms is improved from 10-7 to 10-8, the precision of experiment using different spin-orientation atoms reaches the level of 10-7, and the precision of quantum test using superposition-state atoms reaches the level of 10-9. The key problems in the weak equivalence principle test using dual-species atom interferometers are summarized. Advances have been made in vibration noise suppression, frequency shift and phase noise suppression of Raman laser, four-wave double-diffraction Raman-transition atom interference, signal detection and data processing. The development of long-baseline atom interferometers for improving the free evolution time of atoms has progressed. The precision of demonstration experiment of weak equivalence principle test using atom interferometers in weightlessness reaches 10-4 level. The space plan for atom interferometer based weak equivalence principle test is also gradually implemented. The test precision of microparticles' weak equivalence principle using long-baseline atom interferometers or space atom interferometers is expected to reach the level of 10-15-10-17 in the future.