  We present an efficient decoding algorithm for constant rate quantum
hypergraph-product LDPC codes which provably corrects adversarial errors of
weight $\Omega(\sqrt{n})$ for codes of length $n$. The algorithm runs in time
linear in the number of qubits, which makes its performance the strongest to
date for linear-time decoding of quantum codes. The algorithm relies on
expanding properties, not of the quantum code's factor graph directly, but of
the factor graph of the original classical code it is constructed from.
