In Situ-Tunable Spin–Spin Interactions in a Penning Trap with In-Bore Optomechanics

Experimental implementations of quantum simulation must balance control-field-induced decoherence with the controllability of the quantum system. The ratio of coherent interaction strength to decoherence induced by stimulated emission in atomic systems is typically determined by hardware constraints, limiting the flexibility needed to explore different operating regimes. Here, an optomechanical system is presented for in situ tuning of the coherent spin-motion and spin-spin interaction strength in 2D ion crystals in a Penning trap. Enabled by precision closed-loop piezo-actuated positioners integrated into the confined space of a superconducting magnet's bore, the system allows tuning of the angle-of-incidence of Raman laser beams up to ${\theta }_{\mathrm{ODF}}\approx {28}^{\circ }$, governing the ratio of coherent to incoherent light-matter interaction for fixed optical power. System characterization involves measurements of the induced mean-field spin precession under the application of an optical dipole force in ion crystals cooled below the Doppler limit through electromagnetically induced transparency cooling. These experiments show approximately a $\times 2$ variation in the coherent to incoherent interaction ratio with changing ${\theta }_{\text{ODF}}$, consistent with theoretical predictions. The system stability is characterized over 6000 s, resulting in a drift rate of $0.{002}^{\circ }$ h^–1. These technical developments will be crucial in future quantum simulations and sensing applications.