# Direct temperature determination of a sympathetically cooled large 113Cd+ ion crystal for a microwave clock

## TL;DR

This study measures the temperature of large sympathetically cooled 113Cd+ ion crystals using laser-cooled 24Mg+ ions, demonstrating their potential for highly stable microwave atomic clocks with reduced frequency shifts.

## Contribution

It provides the first direct temperature measurement of large 113Cd+ ion ensembles cooled sympathetically, highlighting their suitability for advanced microwave clock applications.

## Key findings

- Minimum ion temperature reached tens of mK
- Second order Doppler shift reduced by two orders of magnitude
- Dick effect suppression demonstrated

## Abstract

This paper reports the direct temperature determination of sympathetically cooled 113Cd+ ions with laser-cooled 24Mg+ in a linear Paul trap. The sympathetically cooled ion species distribute in the outer shell of the large ensembles, which contain up to 3.3E5 ions. With optimized parameters, the minimum temperature of the sympathetically cooled 113Cd+ ions was measured to be tens of mK. These results indicate promising performance for microwave atomic clocks. The second order Doppler frequency shift is two orders of magnitudes lower and the Dick effect is suppressed.

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Source: https://tomesphere.com/paper/1902.10907