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  • Open Access

Nonparaxial effects on laser-qubit operations

Louis P. H. Gallagher1,*, Matteo Mazzanti2,3, Zeger E. D. Ackerman1, Arghavan Safavi-Naini1,4, Rene Gerritsma1,4, and Robert J. C. Spreeuw1,4

  • 1Van der Waals-Zeeman Institute, Institute of Physics, University of Amsterdam, 1098 XH Amsterdam, The Netherlands
  • 2Institute for Quantum Electronics, ETH Zürich, Otto-Stern-Weg 1, 8093 Zürich, Switzerland
  • 3Quantum Center, ETH Zürich, 8093 Zürich, Switzerland
  • 4QuSoft, Science Park 123, 1098 XG Amsterdam, The Netherlands

  • *Contact author: l.p.h.gallagher@uva.nl
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Phys. Rev. Research 8, 013077 – Published 26 January, 2026

DOI: https://doi.org/10.1103/4ylp-h3qr

Abstract

Tightly focused laser beams, or optical tweezers, are essential for analog and digital quantum simulation with neutral atoms and trapped ions. Despite this, most of the current intuition and theoretical treatment utilizes the paraxial approximation, which is an insufficient description at the focus of tightly focused optical tweezers. We develop an analytic model, which we use in tandem with numerical simulations, to quantify how nonparaxial effects will manifest in the next generation of scalable quantum hardware, where tightly focused beams are used for individual qubit control. In particular, we calculate the light potentials of Gaussian and Laguerre-Gaussian beams driving the quadrupole S1/22→D5/22 transition in Ca+40. Longitudinal field components in the beam center cause spatially dependent Rabi frequencies and ac Stark shifts, leading to unexpected qubit-motion coupling. We characterize single- and two-qubit gate infidelities due to this effect with an analytic model and numerical simulation. We identify regimes where nonparaxial effects should be taken into account for high-precision quantum control, and highlight that the effects are potentially more severe for the case of neutral atom and molecule addressing.

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Phys. Rev. Research 8, 013077– Published 26 January, 2026
  • Received 11 August 2025
  • Accepted 17 December 2025
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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