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Universal weakly fault-tolerant quantum computation via code switching in the [[8,3,2]] code

Shixin Wu1,2,*, Dawei Zhong2,3, Todd A. Brun1,2,3,4, and Daniel A. Lidar1,2,3,5,6

  • *Contact author: shixinwu@usc.edu
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Phys. Rev. Research 8, 033380 – Published 30 September, 2026

DOI: https://doi.org/10.1103/4gwn-6cnx

Abstract

Code switching offers a route to universal, fault-tolerant quantum computation by circumventing the limitation implied by the Eastin-Knill theorem against a universal transversal gate set within a single quantum code. Here, we present a fault-tolerant code-switching protocol between two versions of the [[8,3,2]] code. One version supports weakly fault-tolerant single-qubit Clifford gates, while the other supports a logical CCZ¯ gate via transversal T/T† together with logical CZ¯, CNOT¯, and SWAP¯ gates. Because both codes have distance 2, the protocol operates in a postselected, error-detecting regime: Single faults lead to detectable outcomes, and accepted runs exhibit quadratic suppression of logical error rates. This yields a universal scheme for postselected fault-tolerant computation. We validate the protocol numerically through simulations of state preparation, interblock logical teleportation, code switching, and a three-logical-qubit implementation of Grover's search.

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Phys. Rev. Research 8, 033380– Published 30 September, 2026
  • Received 6 May 2026
  • Accepted 20 August 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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