High-Stability Single-Ion Clock with 5.5 x 10^-19 Systematic Uncertainty

Published

July 14, 2025

Author(s)

Mason Marshall, Daniel Rodriguez Castillo, Willa Dworschack, Alexander Aeppli, Kyungtae Kim, Dahyeon Lee, William Warfield, Nicholas Nardelli, Tara Fortier, Jun Ye, David Ray Leibrandt, David Hume

Abstract

We report a single-ion optical atomic clock with fractional frequency uncertainty of 5.5 x 10^-19 and frequency stability of 3.5 x 10^-16/sqrttau/s}, based on quantum logic spectroscopy of a single 27Al+ ion. A co-trapped 25Mg+ ion provides sympathetic cooling and quantum logic readout of the 27Al+ 1S0 -> 3P0 clock transition. A Rabi probe duration of 1 s, enabled by laser stability transfer from a remote cryogenic silicon cavity across a 3.6-km fiber link, results in a threefold reduction in instability compared to previous 27Al+ clocks. Systematic uncertainties are lower due to an improved ion trap electrical design, which reduces excess micromotion, and a new vacuum system, which reduces collisional shifts. We also perform a direction-sensitive measurement of the ac magnetic field due to the RF ion trap, eliminating systematic uncertainty due to field orientation.

Citation

Physical Review Letters

Volume

135

Pub Type

Journals

Download Paper

https://doi.org/10.1103/hb3c-dk28

Local Download

Keywords

Atomic clocks, optical clocks, trapped ions, atomic spectroscopy, precision measurement, quantum logic spectroscopy, time and frequency, metrology

Citation

Marshall, M. , Rodriguez Castillo, D. , Dworschack, W. , Aeppli, A. , Kim, K. , Lee, D. , Warfield, W. , Nardelli, N. , Fortier, T. , Ye, J. , Leibrandt, D. and Hume, D. (2025), High-Stability Single-Ion Clock with 5.5 x 10^-19 Systematic Uncertainty, Physical Review Letters, [online], https://doi.org/10.1103/hb3c-dk28, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=959906 (Accessed October 10, 2025)