Direct frequency comb spectroscopy of trapped ions

TL;DR

This paper demonstrates the first direct frequency comb spectroscopy of trapped calcium ions, achieving highly accurate measurement of a specific atomic transition using a novel upconversion and detection scheme.

Contribution

It introduces a new method for direct frequency comb spectroscopy of trapped ions with significantly improved measurement accuracy.

Findings

Measured transition frequency with an uncertainty of 0.5 MHz

Achieved over two orders of magnitude improvement in accuracy

Demonstrated effective background suppression using shelving scheme

Abstract

Direct frequency comb spectroscopy of trapped ions is demonstated for the first time. It is shown that the 4s^2S_(1/2)-4p^2P_(3/2) transition in calcium ions can be excited directly with a frequency comb laser that is upconverted to 393 nm. Detection of the transition is performed using a shelving scheme to suppress background signal from non-resonant comb modes. The measured transition frequency of f=761 905 012.7(0.5) MHz presents an improvement in accuracy of more than two orders of magnitude.