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  • Featured in Physics
  • Open Access

Running a Six-Qubit Quantum Circuit on a Silicon Spin-Qubit Array

I. Fernández de Fuentes1,*,†, E. Raymenants1,*, B. Undseth1, O. Pietx-Casas1, S. Philips1, M. Mądzik1, S.L. de Snoo1, S.V. Amitonov2, L. Tryputen2 et al.

A.T. Schmitz3, A.Y. Matsuura3, G. Scappucci1, and L.M.K. Vandersypen1

  • *These authors contributed equally to this work.
  • †Contact author: ifernandezdefu@tudelft.nl
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PRX Quantum 7, 010308 – Published 14 January, 2026

DOI: https://doi.org/10.1103/f285-l2v5

Abstract

The simplicity of encoding a qubit in the state of a single electron spin and the potential for their integration into industry-standard microchips continue to drive the field of semiconductor-based quantum computing. After a series of key first-principles demonstrations validating universal gate operations, initialization and readout, three-qubit algorithms have already been realized with silicon-based quantum dots in past years. Devices containing more qubits have become available since then but experiments have not gone beyond meeting the DiVincenzo criteria. In this work, we fully exploit the capacity of a spin-qubit array and implement a six-qubit quantum circuit, the largest utilizing semiconductor quantum technology. By programming the quantum processor, we execute quantum circuits across all permutations of three, four, five, and six neighboring qubits, demonstrating successful programmable multi-qubit operation throughout the array. Using an error model that incorporates quasi-static noise allows us to qualitatively explain some key trends in our experimental results and highlight the necessity to minimize idling times through simultaneous operations, extending dephasing times, and consistently improving state preparation and measurement fidelities.

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Benchmarking a Spin-Based Quantum Computer

Published 14 January, 2026

Researchers have quantified the performance of a quantum processor built from semiconductor quantum dots, charting the challenges to scaling up the technology.

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Popular Summary

Among the many approaches to building a quantum computer, using the spin degree of freedom of electrons trapped in tiny quantum wells, or quantum dots, is particularly promising. Their appeal lies in their small size and the possibility of manufacturing quantum chips using the same techniques that power today’s semiconductor industry. Naturally, a key step in validating this platform is demonstrating that it can be used to run quantum algorithms. However, running quantum circuits on more than a couple of these spin qubits remains one of the major challenges in the field.

In this work, we perform the largest fully programmable quantum circuit demonstrated to date on a linear array of gate-defined silicon quantum dots. Using an array of six spin qubits, we execute a quantum protocol inspired by dynamical quantum phase transitions. We implement this quantum circuit for all permutations of three, four, five, and all six qubits and use two key observables—the Loschmidt echo and the spin magnetization—to show the expected behavior across all configurations. Moreover, we compare our measurements to numerical simulations that include low-frequency noise, typically the most detrimental form of noise in these devices. The qualitative agreement helps pinpoint where further progress will matter most: improving coherence times, increasing operational parallelism, and refining state preparation and readout.

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PRX Quantum 7, 010308– Published 14 January, 2026
  • Received 25 May 2025
  • Revised 18 September 2025
  • Accepted 13 November 2025
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