Testing General Relativity and Alternative Theories of Gravity with Space-based Atomic Clocks and Atom Interferometers

TL;DR

This paper explores how space-based atomic clocks and atom interferometers can test general relativity and alternative gravity theories by analyzing gravitational effects on spacecraft trajectories and clock signals.

Contribution

It proposes a satellite experiment using highly accurate clocks to measure relativistic effects and constrain parameters of gravity theories around Earth.

Findings

A satellite with a fractional timing inaccuracy of 10^{-16} can constrain PPN parameters to 10^{-6}.

The method can differentiate between general relativity and alternative theories.

Potential constraints on scalar tensor theories like Chameleon and dilaton models.

Abstract

The successful miniaturisation of extremely accurate atomic clocks and atom interferometers invites prospects for satellite missions to perform precision experiments. We discuss the effects predicted by general relativity and alternative theories of gravity that can be detected by a clock, which orbits the Earth. Our experiment relies on the precise tracking of the spacecraft using its observed tick-rate. The spacecraft's reconstructed four-dimensional trajectory will reveal the nature of gravitational perturbations in Earth's gravitational field, potentially differentiating between different theories of gravity. This mission can measure multiple relativistic effects all during the course of a single experiment, and constrain the Parametrized Post-Newtonian Parameters around the Earth. A satellite carrying a clock of fractional timing inaccuracy of $\Delta f/f \sim 10^{-16}$ in an elliptic orbit around the Earth would constrain the PPN parameters $|\beta -1|, |\gamma-1| \lesssim 10^{-6}$. We also briefly review potential constraints by atom interferometers on scalar tensor theories and in particular on Chameleon and dilaton models.