Cavity-based atom interferometry for testing gravity and dark-sector physic

University Of California-Berkeley, Berkeley CA

Investigators

Abstract

This project will pioneer new measurements of the gravitational interaction between atoms and a 100-gram mass. To make sensitive measurements, this project will use an atom interferometer to study how gravity affects the quantum phase of atoms. New tests of gravitational physics are crucial for studying the nature of Dark Energy and Dark Matter, and thus understanding the history and fate of the universe. Precise measurements of gravity can also improve military and commercial navigation, and help study underground resources such as mineral ore deposits and groundwater aquifers. This project will train students to develop advanced atom interferometry technology that will have many applications in atomic and molecular physics, navigation, and fundamental studies of gravity. The fact that gravity is so weak relative to the other fundamental forces of nature has made it relatively elusive. For example, gravitational interactions between two individual atoms cannot yet be measured. This is a major obstacle for gaining a better understanding of hypothetical new forces that could arise from cosmological dark energy (which is thought to drive the accelerated expansion of the universe) and the effects of gravity in the microscopic world, where the laws of quantum mechanics apply. This research team has built the first instrument (an atom interferometer) able to measure the gravitational force between individual atoms and a miniature (1-inch diameter) source mass. For this project they will apply this unique instrument to perform several new experiments. First, they will use it to look for evidence for small corrections to the gravitational force that might arise as a consequence of cosmological Dark Energy. This will close the gap that exists in the parameter space between results from microscopic experiments (colliders, atomic structure, and atom and neutron interferometers) and macroscopic ones (torsion balances and solar system physics). Second, they will improve the instrument by extending the coherence time of the atoms to 10 seconds, which would be the longest demonstrated in any matter-wave interferometer. The instrument will then be used to demonstrate the gravitational Aharonov-Bohm effect, an effect of gravity on the quantum state of a particle, which can only be observed with a quantum sensor such as an atom interferometer.