2015/05/31 by J. Keller, H. L. Partner, T. Burgermeister +1 · 3 citations
Physics and Astronomy · #physics.atom-ph #quant-ph
paper · pdf · doi:10.1063/1.4930037
published as J. Appl. Phys. 118, 104501 (2015) · 13 pages, 13 figures
arxiv created 2015/11/17 · arxiv updated 2015/11/18
As relative systematic frequency uncertainties in trapped-ion spectroscopy are approaching the low 10-18 range, motional frequency shifts account for a considerable fraction of the uncertainty budget. Micromotion, a driven motion fundamentally connected to the principle of the Paul trap, is a particular concern in these systems. In this article, we experimentally investigate at this level three common methods for minimizing and determining the micromotion amplitude. We develop a generalized model for a quantitative application of the photon-correlation technique, which is applicable in the commonly encountered regime where the transition linewidth is comparable to the rf drive frequency. We show that a fractional frequency uncertainty due to the 2nd-order Doppler shift below 1× 10-20 can be achieved. The quantitative evaluation is verified in an interleaved measurement with the conceptually simpler resolved sideband method. If not performed deep within the Lamb-Dicke regime, a temperature-dependent offset at the level of 10-19 is observed in resolved sideband measurements due to sampling of intrinsic micromotion. By direct comparison with photon-correlation measurements, we show that the simple to implement parametric heating method is sensitive to micromotion at the level of 1× 10-20 as well.