Optical clock comparison for Lorentz symmetry testing.

Area of Science:

• * Fundamental Physics
• * Atomic Physics
• * Relativity

Background:

• * Advanced atomic clocks enable precise tests of spacetime symmetries.
• * Modern research seeks to detect violations of Lorentz symmetry, a cornerstone of relativity.
• * Optical clock frequency comparisons offer a promising avenue for enhanced tests of relativity.

Purpose of the Study:

• * To experimentally compare two single-ion optical clocks with unprecedented precision.
• * To validate the uncertainty budgets of these state-of-the-art clocks.
• * To search for hypothetical violations of Lorentz symmetry by analyzing clock frequency offsets.

Main Methods:

• * Utilized two single-ion optical clocks employing ytterbium ions.
• * Confined ions in separate ion traps with non-parallel quantization axis alignment.
• * Conducted a six-month comparison period to detect periodic modulations in frequency offset.

Main Results:

• * Demonstrated agreement between the two optical clocks at the 10⁻¹⁸ level.
• * Validated the uncertainty budgets of the clocks directly.
• * Established stringent limits of the order of 10⁻²¹ on Lorentz symmetry violation parameters for electrons, improving previous limits by two orders of magnitude.

Conclusions:

• * The experiment provides the most stringent limits to date on Lorentz symmetry violation for electrons.
• * The high precision achieved is crucial for future low-energy tests of quantum gravity theories.
• * Findings support the fundamental principles of Einstein's theory of relativity at unprecedented accuracy levels.