Transportable Optical Lattice Clocks and General Relativity

TL;DR

This paper discusses the use of transportable optical lattice clocks to test general relativity by measuring gravitational redshift and explores future applications like gravitational wave detection and relativistic geodesy.

Contribution

It reports experimental measurements of gravitational redshift using transportable optical lattice clocks and discusses potential future applications and tests of fundamental physics.

Findings

Successful measurement of gravitational redshift between RIKEN and Tokyo using transportable OLCs

Potential for space-based gravitational wave detection with OLCs

Discussion of testing post-Newtonian parameters around Earth

Abstract

Optical lattice clocks (OLCs) enable us to measure time and frequency with a fractional uncertainty at $10^{-18}$ level, which is 2 orders of magnitude better than Cs clocks. In this article, after briefly reviewing OLCs and the history of testing the fundamental principles of general relativity, we report our experiments of measuring the gravitational redshift between RIKEN and The University of Tokyo, and at Tokyo Skytree using transportable OLCs. We also discuss a couple of future applications of OLCs, such as detecting gravitational waves in space and relativistic geodesy. The possibility of testing second-order parametrized post-Newtonian potential around the Earth is also mentioned.