Micromotion-Synchronized Pulsed Doppler Cooling of Trapped Ions

TL;DR

This paper introduces a novel pulsed Doppler cooling method synchronized with trap RF to achieve uniform cooling of trapped-ion crystals, especially when micromotion amplitudes are large and uneven.

Contribution

The paper presents a new technique for Doppler cooling that uses RF-synchronized pulses to improve uniformity in ion crystals with large micromotion.

Findings

Effective cooling at micromotion nodes

Theoretical framework for practical implementation

Experimental demonstration of the method

Abstract

We propose and demonstrate a new method for Doppler cooling trapped-ion crystals where the distribution of micromotion amplitudes may be large and uneven. The technique uses pulses of Doppler cooling light synchronized with the trap RF that selectively target ions when their velocity is near a node, leading to more uniform cooling across a crystal by a single tone of cooling light. We lay out a theoretical framework that describes where this technique is practical, and provide a simple experimental demonstration.