Universal quantum computing with twist-free and temporally encoded lattice surgery


Abstract in English

Lattice surgery protocols allow for the efficient implementation of universal gate sets with two-dimensional topological codes where qubits are constrained to interact with one another locally. In this work, we first introduce a decoder capable of correcting spacelike and timelike errors during lattice surgery protocols. Afterwards, we compute logical failure rates of a lattice surgery protocol for a full biased circuit-level noise model. We then provide a new protocol for performing twist-free lattice surgery. Our twist-free protocol reduces the extra circuit components and gate scheduling complexities associated with the measurement of higher weight stabilizers when using twists. We also provide a protocol for temporally encoded lattice surgery that can be used to reduce both runtimes and the total space-time costs of quantum algorithms. Lastly, we propose a layout for a quantum processor that is more efficient for surface codes exploiting noise bias, and which is compatible with the other techniques mentioned above.

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