Automatic minimisation of micromotion in a 88Sr+ optical clock. (12th June 2015)

• Record Type: Journal Article
• Authors: Barwood, G P; Huang, G; Klein, H A; Gill, P
• Is Part Of: Measurement science & technology. Volume 26:Number 7(2015:Jul.)
• Publication Date: 2015-06-12
• Subjects: ion cooling -- time and frequency -- computer control systems; Physical measurements -- Periodicals; Scientific apparatus and instruments -- Periodicals; Equipment and Supplies -- Periodicals; Science -- instrumentation -- Periodicals; Technology -- instrumentation -- Periodicals; Mesures physiques -- Périodiques; Physical measurements; Scientific apparatus and instruments; Periodicals; 502.87
• DOI: 10.1088/0957-0233/26/7/075203
• Languages: English
• ISSNs: 0957-0233

Abstract

Abstract: Optical clocks based on narrow linewidth transitions in single cold ions confined in RF traps are being developed at a number of laboratories worldwide. For these ion clock systems, excess micromotion can cause both Stark and Doppler frequency shifts and also a degradation of frequency stability as a result of a reduced excitation rate to the clock transition. At NPL, we detect micromotion in our 88 Sr + optical clocks by observing the correlation between photon arrival times and the zero crossing of the RF trap drive signal. Recently, two nominally identical 88 Sr + optical clocks have been operated over several days and their frequencies compared against one another. During this time the dc voltages on the endcap and compensation voltage electrodes required to minimise the micromotion can change significantly, particularly following the loading of an ion. This paper describes an automatic method to monitor and minimise micromotion applicable to single ion clocks and which we demonstrate using our two NPL 88 Sr + ion clocks.