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arXiv · 2606.00940

Programmable coherent site-selective spin control in rotating Penning-trap ion crystals

Nihar Makadia·Julian Y. Z. Jee·Gustavo Café de Miranda·Joseph H. Pham·Michael J. Biercuk·Athreya Shankar·Robert N. Wolf
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Abstract

Large ion crystals in Penning traps provide a platform for quantum simulation and sensing with hundreds of spins, but their continuous rigid-body rotation has so far limited flexible local qubit control. Here we demonstrate programmable coherent site-selective spin control across large rotating ${}^{9}\mathrm{Be}^{+}$ crystals in a Penning trap. A tightly focused off-resonant laser beam drives local $R_z$ phase rotations via differential AC Stark shifts. Beam steering synchronised with crystal rotation enables addressing of arbitrary ions throughout the crystal. Ramsey-based characterisation shows $R_z(\pi)$ gate fidelity of 0.950(4) and nearest-neighbour crosstalk error of 0.021(6). We demonstrate preparing spatially structured spin patterns, generating a biskyrmion spin texture in a single-layer crystal, and then extend the method to bilayer crystals where we perform layer-selective addressing operations. We further demonstrate dual-quadrature Ramsey sensing by imprinting a relative $\pi/2$ phase shift between spatial sub-ensembles, enabling simultaneous measurement of orthogonal spin components within a single experimental realisation. These results establish programmable local control in large rotating ion crystals, opening new routes for engineering spatially structured quantum states in multidimensional trapped-ion systems.

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Nihar Makadia, Julian Y. Z. Jee, Gustavo Café de Miranda, Joseph H. Pham, Michael J. Biercuk, Athreya Shankar, Robert N. Wolf. 2026-05-31. Programmable coherent site-selective spin control in rotating Penning-trap ion crystals. https://arxiv.org/abs/2606.00940

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