Single ions trapped in a one-dimensional optical lattice

TL;DR

This paper demonstrates the three-dimensional optical trapping of single ions in a standing wave lattice, analyzes heating effects, and proposes an improved transfer protocol to mitigate rf-induced excitations, advancing ion trapping for quantum and chemical experiments.

Contribution

It introduces a method for trapping single ions in a 1D optical lattice and presents a protocol to reduce rf-induced heating effects during transfer.

Findings

Dominant heating rate observed during rf to optical transfer.

Monte Carlo simulations confirm rf-induced parametric excitations.

An alternative transfer protocol avoids rf overlap, reducing heating.

Abstract

We report on three-dimensional optical trapping of single ions in an optical lattice formed by two counter-propagating laser beams. We characterize the trapping parameters of the standing wave using the ion as a sensor stored in a hybrid trap consisting of a radio-frequency (rf), a dc, and the optical potential. When loading ions directly from the rf into the standing-wave trap, we observe a dominant heating rate. Monte Carlo simulations confirm rf-induced parametric excitations within the deep optical lattice as the main source. We demonstrate a way around this effect by an alternative transfer protocol which involves an intermediate step of optical confinement in a single-beam trap avoiding the temporal overlap of the standing wave and the rf field. Implications arise for hybrid (rf/optical) and pure optical traps as platforms for ultra-cold chemistry experiments exploring atom--ion collisions or quantum simulation experiments with ions, or combinations of ions and atoms.