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Fast Design and Scaling of Multiqubit Gates in Large-Scale Trapped-Ion Quantum Computers

Lee Peleg1,3,*,†, David Schwerdt1,*, Jonathan Nemirovsky1,3,*, Yotam Shapira1,3,*, Nitzan Akerman1, Ady Stern2, Amit Ben Kish3, and Roee Ozeri1

  • *These authors contributed equally to this work.
  • †lee.peleg@quantum-art.tech
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PRX Quantum 7, 033021 – Published 31 July, 2026

DOI: https://doi.org/10.1103/r78y-3q89

Abstract

Quantum computers based on crystals of trapped ions are a prominent technology for quantum computation. A unique feature of trapped ions is their long-range Coulomb interactions, which can be exploited to realize large-scale multiqubit entanglement gates. However, scaling up the number of qubits, N, in these systems, while retaining high-fidelity and high-speed operations, is challenging. Specifically, designing multiqubit entanglement gates in long ion crystals of hundreds of ions involves an NP-hard optimization problem, rendering scale-up not only a technological challenge, but also a conceptual challenge. Here we introduce a method that mitigates this challenge, effectively allowing for a polynomial-time design of fast, robust, and programmable entanglement gates, acting on the entire ion-crystal. We show that while the number of simultaneous entanglement operations scales as N2, the gate duration scales as N, leading to a scaling advantage. We use our methods to investigate the drive-power requirements and susceptibility to noise and errors of these multiqubit gates. Our method delineates a path toward scaling up quantum computers based on ion-crystals with hundreds of qubits.

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Popular Summary

Trapped-ion quantum computers are promising because ions interact through shared motion, enabling programmable entangling gates that can couple many qubit pairs within a single operation. Scaling this capability to long ion chains is difficult: as the number of ions grows, the number of target pairwise couplings grows quadratically, and designing laser pulses that realize them becomes a hard constrained optimization problem. We introduce the large-scale fast (LSF) method, a computational framework for designing individual-ion laser pulses that implement general multiqubit entangling gates across large ion crystals. LSF exploits the structure of the gate-design problem to find high-fidelity pulse solutions much faster than standard optimization approaches. We apply the method to chains of up to 100 ions and study how gate resources scale with system size and coupling complexity. We find that, although the number of simultaneous pairwise couplings grows quadratically, the minimum gate time grows only linearly. We also derive a practical estimate for the required drive amplitude and analyze sensitivity to common sources of noise. These results suggest a route toward scalable programmable multiqubit control in large trapped-ion processors, while also identifying noise and power requirements that future implementations must meet.

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PRX Quantum 7, 033021– Published 31 July, 2026
  • Received 12 March 2026
  • Accepted 4 June 2026
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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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