Local pre-matching pass for correlated decoding of quantum error correcting codes

A system comprising:

• one or more data processing apparatuses;
• and
• non-transitory computer readable storage media in data communication with the one or more data processing apparatuses and storing instructions that, when executed by the data processing apparatuses, cause the one or more data processing apparatuses to perform operations for decoding measurement data received from a quantum computer that performs a quantum computation, the operations comprising:
• obtaining measurement data from a quantum computer that performs a quantum computation;
• generating, using the measurement data, a first detector graph, wherein the first detector graph labels a first set of detection events that occur in the measurement data and each edge in the first detector graph is weighted;
• generating, using the measurement data, a second detector graph, wherein the second detector graph labels a second set of detection events that occur in the measurement data, the second set of detection events being different to the first set of detection events, and each edge in the second detector graph is weighted;
• for each detection event in the first detector graph:
• identifying one or more edges in the first detector graph that are incident to the detection event;
• and
• processing the identified one or more edges in sequence, comprising, for each edge that is incident to the detection event and is connected to another detection event, labelling the edge as a candidate error mechanism;
• and
• for each edge labelled as a candidate error mechanism, updating respective weights of one or more complementary edges in the second detector graph to generate an updated second detector graph;
• and
• executing a decoding process on the updated second detector graph to compute a decoding output of the decoding process, wherein the decoding output predicts an occurrence of errors in the quantum computation.

A computer-readable storage medium comprising instructions stored thereon that are executable by a processing device and upon such execution cause the processing device to perform operations for decoding measurement data received from a quantum computer that performs a quantum computation, the operations comprising:

• obtaining measurement data from a quantum computer that performs a quantum computation;
• generating, using the measurement data, a first detector graph, wherein the first detector graph labels a first set of detection events that occur in the measurement data and each edge in the first detector graph is weighted;
• generating, using the measurement data, a second detector graph, wherein the second detector graph labels a second set of detection events that occur in the measurement data, the second set of detection events being different to the first set of detection events, and each edge in the second detector graph is weighted;
• for each detection event in the first detector graph:
• identifying one or more edges in the first detector graph that are incident to the detection event;
• and
• processing the identified one or more edges in sequence, comprising, for each edge that is incident to the detection event and is connected to another detection event, labelling the edge as a candidate error mechanism;
• and
• for each edge labelled as a candidate error mechanism, updating respective weights of one or more complementary edges in the second detector graph to generate an updated second detector graph;
• and
• executing a decoding process on the updated second detector graph to compute a decoding output of the decoding process, wherein the decoding output predicts an occurrence of errors in the quantum computation.

A system comprising:

• one or more data processing apparatuses;
• and
• non-transitory computer readable storage media in data communication with the one or more data processing apparatuses and storing instructions that, when executed by the data processing apparatuses, cause the one or more data processing apparatuses to perform operations for predicting an occurrence of errors in a quantum computation, the operations comprising:
• updating edge weights of a second quantum error correction detector graph by performing a local search of a first quantum error correction detector graph, wherein performing the local search comprises, for each detection event in the first quantum error correction detector graph, reweighting complementary edges in the second quantum error correction detector graph using single-edge errors on an edge that connects the detection event to a nearest other detection event;
• and
• executing a decoding process on the second quantum error correction detector graph to compute a decoding output of the decoding process, wherein the decoding output predicts the occurrence of errors in the quantum computation.