%0 Electronic Article
%A Besedin, Ilya
%A Kerschbaum, Michael
%A Knoll, Jonathan
%A Hesner, Ian
%A Bödeker, Lukas
%A Colmenarez, Luis
%A Hofele, Luca
%A Lacroix, Nathan
%A Hellings, Christoph
%A Swiadek, François
%A Flasby, Alexander
%A Panah, Mohsen Bahrami
%A Zanuz, Dante Colao
%A Müller, Markus
%A Wallraff, Andreas
%T Realizing Lattice Surgery on Two Distance-Three Repetition Codes with Superconducting Qubits
%N arXiv:2501.04612
%M FZJ-2025-01517
%M arXiv:2501.04612
%D 2025
%Z 19 pages, 13 figures
%X Quantum error correction is needed for quantum computers to be capable of fault-tolerantly executing algorithms using hundreds of logical qubits. Recent experiments have demonstrated subthreshold error rates for state preservation of a single logical qubit. In addition, the realization of universal quantum computation requires the implementation of logical entangling gates. Lattice surgery offers a practical approach for implementing such gates, particularly in planar quantum processor layouts. In this work, we demonstrate lattice surgery between two distance-three repetition-code qubits by splitting a single distance-three surface-code qubit. Using a quantum circuit fault-tolerant to bit-flip errors, we achieve an improvement in the value of the decoded $ZZ$ logical two-qubit observable compared to a similar non-encoded circuit. By preparing the surface-code qubit in initial states parametrized by a varying polar angle, we evaluate the performance of the lattice surgery operation for non-cardinal states on the logical Bloch sphere and employ logical two-qubit tomography to reconstruct the Pauli transfer matrix of the operation. In this way, we demonstrate the functional building blocks needed for lattice surgery operations on larger-distance codes based on superconducting circuits.
%F PUB:(DE-HGF)25
%9 Preprint
%U https://juser.fz-juelich.de/record/1038532