Universal Weakly Fault-Tolerant Quantum Computation via Code Switching in the [[8,3,2]] Code

Fuente: arXiv
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Main Authors: Wu, Shixin, Zhong, Dawei, Brun, Todd A., Lidar, Daniel A.
Format: Preprint
Published: 2026
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author Wu, Shixin
Zhong, Dawei
Brun, Todd A.
Lidar, Daniel A.
author_facet Wu, Shixin
Zhong, Dawei
Brun, Todd A.
Lidar, Daniel A.
contents 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 $\overline{\mathrm{CCZ}}$ gate via transversal $T/T^\dagger$ together with logical $\overline{\mathrm{CZ}}$, $\overline{\mathrm{CNOT}}$, and $\overline{\mathrm{SWAP}}$ 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, code switching, and a three-logical-qubit implementation of Grover's search.
format Preprint
id arxiv_https___arxiv_org_abs_2603_15610
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Universal Weakly Fault-Tolerant Quantum Computation via Code Switching in the [[8,3,2]] Code
Wu, Shixin
Zhong, Dawei
Brun, Todd A.
Lidar, Daniel A.
Quantum Physics
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 $\overline{\mathrm{CCZ}}$ gate via transversal $T/T^\dagger$ together with logical $\overline{\mathrm{CZ}}$, $\overline{\mathrm{CNOT}}$, and $\overline{\mathrm{SWAP}}$ 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, code switching, and a three-logical-qubit implementation of Grover's search.
title Universal Weakly Fault-Tolerant Quantum Computation via Code Switching in the [[8,3,2]] Code
topic Quantum Physics
url https://arxiv.org/abs/2603.15610