A Modified MWPM Decoding Algorithm for Quantum Surface Codes Over Depolarizing Channels
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Abstract
A quantum surface code is a quantum topological stabilizer code whose stabilizers and qubits are geometrically related. Due to their special structures, surface codes have great potential to be implemented in large-scale quantum computing systems. In the minimum weight perfect matching (MWPM) decoding of surface codes, bit-flip errors and phase-flip errors are assumed to be independent for simplicity. However, these two kinds of errors are likely to be correlated in the real world. In this paper, we propose a modification to the MWPM decoding for surface codes to deal with the noise in depolarizing channels where bit-flip errors and phase-flip errors are correlated. With this modification, we obtain thresholds of 17% and 15.3% for surface codes with mixed boundaries and surface codes with a hole, respectively.