Site-resolved imaging of beryllium ion crystals in a high-optical-access Penning trap with inbore optomechanics

TL;DR

This paper details the design and implementation of a sophisticated experimental system for quantum simulation with hundreds of beryllium-9 ion qubits in a high-access Penning trap, emphasizing optical access, magnetic field homogeneity, and site-resolved imaging.

Contribution

It introduces a novel integrated system with a dual-trap design, advanced optomechanics, and high-homogeneity magnetic fields enabling large-scale ion crystal experiments.

Findings

Achieved site-resolved imaging of ion crystals.

Demonstrated control of planar and 3D ion arrays.

Established a highly homogeneous magnetic field over 7 mm volume.

Abstract

We present the design, construction and characterization of an experimental system capable of supporting a broad class of quantum simulation experiments with hundreds of spin qubits using Be-9 ions in a Penning trap. This article provides a detailed overview of the core optical and trapping subsystems, and their integration. We begin with a description of a dual-trap design separating loading and experimental zones and associated vacuum infrastructure design. The experimental-zone trap electrodes are designed for wide-angle optical access (e.g. for lasers used to engineer spin-motional coupling across large ion crystals) while simultaneously providing a harmonic trapping potential. We describe a near-zero-loss liquid-cryogen-based superconducting magnet, employed in both trapping and establishing a quantization field for ion spin-states, and equipped with a dual-stage remote-motor LN2LHe recondenser. Experimental measurements using a nuclear magnetic resonance (NMR) probe demonstrate part-per-million homogeneity over 7 mm-diameter cylindrical volume, with no discernible effect on the measured NMR linewidth from pulse-tube operation. Next we describe a custom-engineered inbore optomechanical system which delivers ultraviolet (UV) laser light to the trap, and supports multiple aligned optical objectives for top- and sideview imaging in the experimental trap region. We describe design choices including the use of non-magnetic goniometers and translation stages for precision alignment. Further, the optomechanical system integrates UV-compatible fiber optics which decouple the system's alignment from remote light sources. Using this system we present site-resolved images of ion crystals and demonstrate the ability to realize both planar and three-dimensional ion arrays via control of rotating wall electrodes and radial laser beams. Looking to future work, we include interferometric..