Atom Interferometers and the Gravitational Redshift

From the principle of equivalence, Einstein predicted that clocks slowdown in a gravitational field. Since the general theory of relativity is based on the principle of equivalence, it is essential to test this prediction accurately. There is an ongoing controversy regarding the sensitivity of atom interferometry to test the gravitational redshift. This talk will explain the issues involved and suggest a resolution. Finally, we propose a new interferometric experiment to measure the gravitational redshift, which realizes a quantum version of theclassical clock 'paradox'.