Test of Time Dilation Using Stored Li+ Ions as Clocks at Relativistic Speed

TL;DR

This experiment used stored 7Li+ ions at relativistic speeds to precisely test time dilation predicted by special relativity, confirming the relation with high accuracy and exploring potential Lorentz invariance violations.

Contribution

First high-precision test of time dilation using stored Li+ ions at relativistic speeds with optical spectroscopy, verifying special relativity to within 2.3 ppb.

Findings

Confirmed the special relativity time dilation relation with 2.3 ppb accuracy.

Measured Doppler shifted frequencies with <4 ppb precision.

Provided constraints on Lorentz invariance violation theories.

Abstract

We present the concluding result from an Ives-Stilwell-type time dilation experiment using 7Li+ ions confined at a velocity of beta = v/c = 0.338 in the storage ring ESR at Darmstadt. A Lambda-type three-level system within the hyperfine structure of the 7Li+ triplet S1-P2 line is driven by two laser beams aligned parallel and antiparallel relative to the ion beam. The lasers' Doppler shifted frequencies required for resonance are measured with an accuracy of < 4 ppb using optical-optical double resonance spectroscopy. This allows us to verify the Special Relativity relation between the time dilation factor gamma and the velocity beta to within 2.3 ppb at this velocity. The result, which is singled out by a high boost velocity beta, is also interpreted within Lorentz Invariance violating test theories.