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

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 relevant subsystems and their integration. We begin with a description of a dual-trap design separating loading and experimental zones. The experimental zone trap electrodes are designed to provide wide-angle optical access for lasers as required for the engineering of 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 LN2/LHe recondenser. Experimental measurements via a nuclear-magnetic-resonance (NMR) probe demonstrate part-per-million homogeneity over 7 mm-diameter cylindrical volume, and confirm that the pulse tube does not have a discernible effect on the measured NMR linewidth. Next we describe a custom-engineered inbore optomechanical system which delivers UV laser light to the trap and holds 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 optomechanics feature integration of UV-compatible fiber optics decoupling the system 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 by rotating wall electrodes and radial laser beams. The paper concludes with a brief outlook towards extensions of the experimental setup and future studies.