Abstract: A technique for performing lattice surgery without using twists is disclosed. Also, an error correcting code and decoder is provided that allows for error decoding of Pauli measurements performed in association with a lattice surgery operation. This allows for overall run-times of lattice surgery to be reduced. For example, some level of errors are tolerable, because they can be corrected, thus fewer measurement rounds (dm) may be performed for a given round of Pauli measurements. Additionally, a temporal encoding of lattice surgery technique is provided, which may additionally or alternatively be used to shorten run times. Also, a quantum computer layout is provided, wherein the layout includes a core computing region and a cache region. Also, protocols for swapping logical qubits between the core and cache are provided.

Abstract: A method and apparatus for decoding syndromes of a quantum error correction code is disclosed. The method includes the steps of receiving syndrome data for a plurality of quantum error correction rounds performed on a plurality of qubits; identifying a plurality of first blocks within the syndrome data, wherein each first block has a respective first central block surrounded by one or more respective first buffer blocks; decoding each first block to obtain a first committed correction for each respective first central block; identifying a plurality of second blocks within the syndrome data, wherein each second block comprises at least part of at least one first buffer block; and decoding each second block to obtain a second committed correction for each second block. An apparatus including a plurality of block decoders and a process manager is disclosed.

Abstract: A computer-implemented method for decoding syndromes of a quantum error correction code, the syndromes comprising measurement data from a quantum computer, the method comprising: receiving syndrome measurement data comprising a plurality of quantum error correction rounds performed on a plurality of qubits; identifying a plurality of non-overlapping first blocks within the syndrome measurement data, wherein: each first block has: a first central block of quantum error corrections rounds; and a first buffer block of quantum error correction rounds, wherein the first buffer block surrounds the first central block, and each first block is surrounded by an interstitial region of quantum error correction rounds; identifying the location of a first set of errors in the plurality of qubits by decoding each first block to provide respective decoded first central blocks and respective decoded first buffer blocks; outputting the location of the first set of errors contained within each decoded first central block.

Abstract: A technique for performing lattice surgery without using twists is disclosed. Also, an error correcting code and decoder is provided that allows for error decoding of Pauli measurements performed in association with a lattice surgery operation. This allows for overall run-times of lattice surgery to be reduced. For example, some level of errors are tolerable, because they can be corrected, thus fewer measurement rounds (dm) may be performed for a given round of Pauli measurements. Additionally, a temporal encoding of lattice surgery technique is provided, which may additionally or alternatively be used to shorten run times. Also, a quantum computer layout is provided, wherein the layout includes a core computing region and a cache region. Also, protocols for swapping logical qubits between the core and cache are provided.