Compatibility of trapped ions and dielectrics at cryogenic temperatures

TL;DR

This study investigates how unshielded dielectrics like optical fibers affect trapped ions in cryogenic surface traps, showing manageable electric fields and heating rates, thus supporting integration of optical components in quantum systems.

Contribution

It provides the first detailed analysis of dielectric-induced effects on ions in cryogenic traps, demonstrating their compatibility for quantum technology applications.

Findings

Stray electric fields up to a few kV/m caused by dielectric are manageable.

Ion heating rates of approximately 30 quanta/sec at 215 μm distance.

Dielectric effects drift slowly and can be compensated with reasonable voltages.

Abstract

We study the impact of an unshielded dielectric $\unicode{x2013}$ here, a bare optical fiber $\unicode{x2013}$ on a $^{40}$Ca${^+}$ ion held several hundred $\mu$m away in a cryogenic surface electrode trap. We observe distance-dependent stray electric fields of up to a few kV/m due to the dielectric, which drift on average less than 10% per month and can be fully compensated with reasonable voltages on the trap electrodes. We observe ion motional heating rates attributable to the dielectric of $\approx$30 quanta per second at an ion-fiber distance of 215(4) $\mu$m and $\approx$1.5 MHz motional frequency. These results demonstrate the viability of using unshielded, trap-integrated dielectric objects such as miniature optical cavities or other optical elements in cryogenic surface electrode ion traps.