Systematic uncertainty due to background-gas collisions in trapped-ion optical clocks
Aaron M. Hankin, Ethan Clements, Huang Yao, Samuel M. Brewer, Jwo-Sy Chen, Chin-wen Chou, David Hume, David Leibrandt
We describe a framework for calculating the frequency shift and uncertainty of trapped-ion optical atomic clocks caused by background-gas collisions, and apply this framework to an 27Al+ quantum-logic clock to enable a total fractional systematic uncertainty below 10-18. For this clock, with 38(19) nPa of room temperature H2 background gas, we find that collisional heating generates a non-thermal distribution of motional states with a mean time-dilation shift of order 10-16. However, the contribution of collisional heating to the spectroscopy signal is highly suppressed and the uncertainty of the -0.6(2.4)x10-19 calculated collision shift is dominated by the unknown collisional phase shift of the 27Al+ superposition state. We experimentally validate the framework and determine the background-gas pressure in situ using measurements of the rate of collisions that cause reordering of mixed-species ion pairs.
, Clements, E.
, Yao, H.
, Brewer, S.
, Chen, J.
, Chou, C.
, Hume, D.
and Leibrandt, D.
Systematic uncertainty due to background-gas collisions in trapped-ion optical clocks, Physical Review Letters, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=927468
(Accessed November 28, 2023)