Quantum probe of space-time curvature

Abstract

In Einstein's theory of general relativity, gravity is a manifestation of spacetime curvature. As predicted by general relativity and confirmed by numerous measurements, clocks moving at different velocities or located in different regions of a gravitational field tick at different rates (1), a phenomenon known as relativistic time dilation. Under appropriate conditions, time dilation can affect the oscillation phase of quantum waves and give rise to a measurable effect in interference experiments. On page 226 of this issue, Overstreet et al. (2) present an atom interferometry experiment in which this effect has been measured for gravitational time dilation. In addition to the importance of the results for fundamental physics, the methods used can lead to more accurate measurements of Newton's gravitational constant, which parametrizes the strength of the gravitational interaction and is by far the least accurately known of all fundamental constants (3).