Non-paraxial effects on laser-qubit interactions

7 Sept 2026, 11:15
25m
Long Talk (20min) Quantum Simulation Quantum Simulation

Speaker

Louis Gallagher

Description

Optical tweezers offer new opportunities to control and manipulate trapped ions with applications in quantum information processing. We consider the light potentials induced on trapped ions by an optical tweezer beyond the paraxial approximation. Longitudinal field components in the beam center cause spatially-dependent Rabi frequencies and AC Stark shifts, leading to unexpected qubit-motion coupling [1]. We characterize single- and two-qubit gate infidelities due to this, and provide strategies to minimize adverse effects [2].
We further detail a novel method for driving a quantum logic gate which uses non-paraxial effects to excite the ion chain's vibrational modes [3]. The proposed gate may offer key benefits such as infrastructural simplification – the light only has to be supplied from one direction - and enhanced long-ranged interactions between the ion qubits. Finally, we detail a novel scheme to implement quadratic spin-phonon coupling using optical tweezers on trapped ions. With the addition of Mølmer-Sørenson-type interactions, we show the resulting system can be used to simulate a class of Bose-Hubbard models [4].

[1] R.J.C. Spreeuw. Physical Review Letters 125, 233201 (2020).
[2] Gallagher, L. P. H., et al. Physical Review Research 8, 013077 (2026).
[3] M. Mazzanti et al. Physical Review Research 5 (3), 033036 (2023).
[4] Gallagher, L. P. H., et al. Physical Review A 112, L020401 (2025).

Academic level PhD student

Author

Louis Gallagher

Co-authors

Dr Arghavan Safavi-Naini Dr Matteo Mazzanti Dr Rene Gerritsma Dr Robert Spreeuw Mr Zeger Ackerman (University of Amsterdam)

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