An apparatus for mitigating loss of fidelity of coded entangled qubit states stored in a memory system comprising: a register configured to store a coded entangled qubit state generated using a quantum stabilizer code; a measurement circuit configured to perform a redundant measurement of a set of syndrome values corresponding to the coded entangled qubit state, wherein the redundant measurement determines a sub-vector (v sub ) of a vector (v), components of the vector (v) being the binary components of a syndrome vector and parity bits of the syndrome vector, the components of the syndrome vector being the syndrome values corresponding to the coded entangled qubit state, the determined sub-vector (v sub ) having a subset of the syndrome values of the syndrome vector as first components thereof and the parity bits as second components thereof, the vector (v) being a codeword of a block error-correction code (C); an erasure-value generator configured to generate a set of binary erasure values for initializing the remaining binary components of the syndrome vector not determined by the redundant measurement; and a decoder configured to determine a probable syndrome vector corresponding to the coded entangled qubit state using a bipartite graph corresponding to the block error-correction code (C) and the sub-vector (v sub ) determined by the redundant measurement of the set of syndrome values, and the decoder being further configured to apply the set of erasure values generated by the erasure-value generator to initialize a set of variable nodes of the bipartite graph not configured to receive a measured syndrome value from the measurement circuit . a register configured to store a coded entangled qubit state generated using a quantum stabilizer code; a measurement circuit configured to perform a redundant measurement of a set of syndrome values corresponding to the coded entangled qubit state, wherein the redundant measurement determines a sub-vector (v sub ) of a vector (v), components of the vector (v) being the binary components of a syndrome vector and parity bits of the syndrome vector, the components of the syndrome vector being the syndrome values corresponding to the coded entangled qubit state, the determined sub-vector (v sub ) having a subset of the syndrome values of the syndrome vector as first components thereof and the parity bits as second components thereof, the vector (v) being a codeword of a block error-correction code (C); an erasure-value generator configured to generate a set of binary erasure values for initializing the remaining binary components of the syndrome vector not determined by the redundant measurement; and a decoder configured to determine a probable syndrome vector corresponding to the coded entangled qubit state using a bipartite graph corresponding to the block error-correction code (C) and the sub-vector (v sub ) determined by the redundant measurement of the set of syndrome values, and the decoder being further configured to apply the set of erasure values generated by the erasure-value generator to initialize a set of variable nodes of the bipartite graph not configured to receive a measured syndrome value from the measurement circuit . <EOS>