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Demonstration of Two-Dimensional Connectivity for a Scalable Error-Corrected Ion-Trap Quantum Processor Architecture

M. Valentini1,*, M. W. van Mourik1,*, F. Butt2,3, J. Wahl1,4, M. Dietl1,4, M. Pfeifer1,4, F. Anmasser1,4, Y. Colombe4, C. Rössler4 et al.

P. C. Holz5, R. Blatt1,5,6, A. Bermudez7, M. Müller2,3, T. Monz1,5, and P. Schindler1,†

  • *These authors contributed equally to this work.
  • †Contact author: philipp.schindler@uibk.ac.at
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Phys. Rev. X 15, 041023 – Published 6 November, 2025

DOI: https://doi.org/10.1103/b9s1-6r44

Abstract

A major hurdle for building a large-scale quantum computer is increasing the number of qubits while maintaining connectivity between them. In trapped-ion devices, this connectivity can be achieved by moving subregisters consisting of a few ions across the processor. Here, we focus on an architecture, which we refer to as the quantum spring array (QSA), that is based on a rectangular two-dimensional lattice of linear strings of ions. Connectivity between adjacent ion strings can be controlled by adjusting their separation. This requires control of trapping potentials along two directions, one along the axis of the ion string and one radial to it. In this work, we investigate key elements of the QSA architecture along both directions: We show that the coupling rate between neighboring lattice sites increases with the number of ions per site and the motion of the coupled system can be resilient to electrical noise, both being key requisites for fast and high-fidelity quantum gate operations. The coherence of the coupling is assessed and an entangling gate between qubits stored in radially separated trapping regions is demonstrated. Moreover, we demonstrate control over radio-frequency signals to adjust the radial separation, and thus the coupling rate, between strings. We further present constructions for the implementation of parallelized, transversal gate operations, and map the QSA architecture to code primitives for fault-tolerant quantum error correction, providing a step towards a quantum processor architecture that is optimized for large-scale operation.

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Popular Summary

Quantum computers hold the potential to solve problems that are far beyond the reach of even the fastest classical supercomputers. Among the various hardware platforms, trapped ions have emerged as one of the most promising technologies, successfully demonstrating small- to medium-scale quantum processors. However, scaling up these systems has been challenging: In existing trap architectures, which are one dimensional, dividing a large group of ions into smaller subregisters introduces significant complexity when the subregisters need to interact. To overcome this, we introduce a 2D ion-trap architecture called the quantum spring array, which arranges ion subregisters in a lattice to reduce this communication overhead.

In our work, we demonstrate the key components required for such a 2D trapped-ion quantum computer. We show that ions can be reliably transported along both directions of the lattice, and we characterize how ions in different subregisters interact. Using this interaction, we successfully create and verify entanglement—a quantum link essential for computation—between two distinct subregisters through universal quantum operations.

These results show that our architecture can maintain high control and low error rates while offering a promising path toward large quantum computers. The next steps will focus on improving the efficiency of ion transport and entangling operations, as well as integrating optical and electronic control components directly into the trapping structure.

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Phys. Rev. X 15, 041023– Published 6 November, 2025
  • Received 5 September 2024
  • Accepted 2 October 2025
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