Tests of local position invariance using continuously running atomic clocks

TL;DR

This paper demonstrates that continuously running atomic clocks can perform local position invariance tests more efficiently and with comparable or higher precision than traditional methods that rely on periodic measurements over many years.

Contribution

It introduces a new method using continuous clock outputs for LPI tests, achieving high precision in less than 1.5 years, and provides new limits on redshift anomalies between different atomic species.

Findings

Achieved a limit of .7 b1 4.9 d7 10^{-7} on eta(Rb) - eta(H)

Demonstrated faster LPI testing with comparable or better precision

Provided new measurements of redshift anomalies in atomic transitions

Abstract

Tests of local position invariance (LPI) made by comparing the relative redshift of atomic clocks based on different atoms have been carried out for a variety of pairs of atomic species. In most cases, several absolute frequency measurements per year are used to look for an annual signal, resulting in tests that can span on order of a decade. By using the output of continuously running clocks, we carry out LPI tests with comparable or higher precision after less than 1.5 years. These include new measurements of the difference in redshift anomalies \beta\ for hyperfine transitions in Rb87 and Cs133 and in H and Cs133 and a measurement comparing Rb87 and H, resulting in a stringent limit on LPI, \beta(Rb) - \beta(H)=(-2.7 +/- 4.9) x 10^(-7). The method of making these measurements for continuous clocks is discussed.