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arXiv · 2511.15989

Explicit construction of low-overhead gadgets for gates on quantum LDPC codes

Paul Webster·Samuel C. Smith·Lawrence Z. Cohen
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Abstract

Quantum low-density parity check (QLDPC) codes can significantly reduce the overhead of quantum computing, provided the methods for performing logical operations do not require substantial space and time resources. A popular method for performing logical operations is by measuring logical Pauli operators. We present a simple, explicit construction for fixed gadgets that can measure arbitrary logical Pauli operators on QLDPC codes when dynamically connected to the code block. We apply this construction to a family of generalised bicycle codes with distances relevant to utility-scale quantum computation ($10\leq d \leq 24$) and show that it reduces the space overhead by at least an order of magnitude compared to corresponding surface code architectures, without increasing the time overhead.

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Paul Webster, Samuel C. Smith, Lawrence Z. Cohen. 2025-11-20. Explicit construction of low-overhead gadgets for gates on quantum LDPC codes. https://arxiv.org/abs/2511.15989

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