Sympathetic cooling schemes for separately trapped ions coupled via image currents

TL;DR

This paper explores theoretical schemes for sympathetically cooling trapped ions, demonstrating that certain methods can achieve significantly lower temperatures more rapidly than traditional techniques, thus enhancing precision measurements.

Contribution

The study introduces and analyzes new sympathetic cooling schemes for trapped ions that outperform existing methods in speed and temperature reduction.

Findings

Two cooling schemes achieve about 10 mK in 10 seconds

Traditional feedback cooling limits to about 1 K in 100 seconds

Applicable to any trapped charged particle with spatial separation

Abstract

Cooling of particles to mK-temperatures is essential for a variety of experiments with trapped charged particles. However, many species of interest lack suitable electronic transitions for direct laser cooling. We study theoretically the remote sympathetic cooling of a single proton with laser-cooled $^9$Be$^+$ in a double-Penning-trap system. We investigate three different cooling schemes and find, based on analytical calculations and numerical simulations, that two of them are capable of achieving proton temperatures of about 10 mK with cooling times on the order of 10 s. In contrast, established methods such as feedback-enhanced resistive cooling with image-current detectors are limited to about 1 K in 100 s. Since the studied techniques are applicable to any trapped charged particle and allow spatial separation between the target ion and the cooling species, they enable a variety of precision measurements based on trapped charged particles to be performed at improved sampling rates and with reduced systematic uncertainties.