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arXiv · 2603.07548

Entangling ions with engineered light gradients

Tommaso Faorlin·Lorenz Panzl·Phoebe Grosser·Pablo Viñas·Alan Kahan·Walter Joseph Hörmann·Yannick Weiser·Giovanni Cerchiari·Thomas Feldker·Alexander Erhard·Georg Jacob·Juris Ulmanis·Rainer Blatt·Alejandro Bermudez·Thomas Monz
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Abstract

Spectral crowding of collective motional modes limits the fidelity of entangling interactions in trapped-ion quantum processors by inducing off-resonant coupling to spectator modes. We introduce a geometric-phase entangling interaction driven by a transverse, time-dependent structured-light force. By applying the force in a plane orthogonal to the optical propagation direction, we reduce the effects of spectral crowding while preserving single-ion addressing. The scheme is compatible with arbitrary qubit encodings, provided that the qubit states experience a differential AC Stark shift. We experimentally realise high-fidelity two-qubit gates with error rates below $5\times10^{-3}$ in ion crystals containing up to 12 ions confined within a single potential well. These results establish gradient-field light-shift gates as a scalable approach to high-fidelity entangling generation in spectrally crowded trapped-ion systems.

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Tommaso Faorlin, Lorenz Panzl, Phoebe Grosser, Pablo Viñas, Alan Kahan, Walter Joseph Hörmann, Yannick Weiser, Giovanni Cerchiari, Thomas Feldker, Alexander Erhard, Georg Jacob, Juris Ulmanis, Rainer Blatt, Alejandro Bermudez, Thomas Monz. 2026-03-08. Entangling ions with engineered light gradients. https://arxiv.org/abs/2603.07548

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