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arXiv · 2306.17142

Belief propagation as a partial decoder

Laura Caune·Brendan Reid·Joan Camps·Earl Campbell
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Abstract

One of the fundamental challenges in enabling fault-tolerant quantum computation is realising fast enough quantum decoders. We present a new two-stage decoder that accelerates the decoding cycle and boosts accuracy. In the first stage, a partial decoder based on belief propagation is used to correct errors that occurred with high probability. In the second stage, a conventional decoder corrects any remaining errors. We study the performance of our two-stage decoder with simulations using the surface code under circuit-level noise. When the conventional decoder is minimum-weight perfect matching, adding the partial decoder decreases bandwidth requirements, increases speed and improves logical accuracy. Specifically, we observe partial decoding consistently speeds up the minimum-weight perfect matching stage by between $2$x-$4$x on average depending on the parameter regime, and raises the threshold from $0.94\%$ to $1.02\%$.

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Laura Caune, Brendan Reid, Joan Camps, Earl Campbell. 2023-06-29. Belief propagation as a partial decoder. https://arxiv.org/abs/2306.17142

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