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arXiv · 2606.06365

A framework for low-overhead quantum fault tolerance via spacetime lifting

Yijia Xu·Yixu Wang·Zi-Wen Liu
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Abstract

Fault-tolerant quantum computation is inherently a spacetime problem, requiring not merely good static quantum error-correcting codes but also low-overhead protocols for protecting and manipulating encoded quantum information over time. Fault complexes provide a homological formalism for treating such protocols as single spacetime objects. Here we initiate the study of low-overhead fault complexes by introducing \emph{spacetime lifting}, a method that constructs fault complexes from symmetry-reduced product structures beyond standard foliation. We show that spacetime lifting yields fault complexes and in particular memory experiments with almost-linear fault distance in the total spacetime cost, which substantially outperforms existing constructions. We further endow fault complexes with the operational interpretation of measurement-based cluster state protocols and identify general conditions under which they realize fault-tolerant logical teleportation, showing that spacetime-lifted constructions combine favorable parameter scaling with operational realizations. Our work establishes a systematic route towards more efficient quantum fault tolerance through general complex constructions.

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Yijia Xu, Yixu Wang, Zi-Wen Liu. 2026-06-04. A framework for low-overhead quantum fault tolerance via spacetime lifting. https://arxiv.org/abs/2606.06365

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