Entangled logical qubits on a superconducting quantum processor

@misc{harper2026entangled,
  title = {{Entangled logical qubits on a superconducting quantum processor}},
  author = {Robin Harper and Xanda C. Kolesnikow and Campbell K. McLauchlan and Georgia M. Nixon and Stephen D. Bartlett and Benjamin J. Brown},
  howpublished = {arXiv},
  year = {2026},
  month = oct,
  doi = {10.48550/arxiv.2610.32347},
  eprint = {2610.32347},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2610.32347},
}

TY  - UNPB
TI  - Entangled logical qubits on a superconducting quantum processor
AU  - Robin Harper
AU  - Xanda C. Kolesnikow
AU  - Campbell K. McLauchlan
AU  - Georgia M. Nixon
AU  - Stephen D. Bartlett
AU  - Benjamin J. Brown
PY  - 2026
DA  - 2026/10/23
PB  - arXiv
DO  - 10.48550/arxiv.2610.32347
UR  - https://arxiv.org/abs/2610.32347
AB  - We demonstrate high-fidelity logical qubit operations using \texttt{ibm\_phoenix}, a square-lattice array of 120 coupled superconducting qubits that are capable of fast reset. Using strategies to exclude underperforming components together with noise informed decoding, we routinely produce surface codes at distance-3 and distance-5 with logical error per round below 1\%. We demonstrate entanglement between two logical qubits, where logical Bell-state fidelities above 93\% are observed for entanglement created via lattice surgery. With three logical qubits and lattice surgery, we perform logical teleportation of a range of states and gates, observing fidelities in the range 78\% - 93\%. Using reset to reduce qubit leakage, we show that repeated rounds of stabilizer measurements continue to exhibit improvements in a stability experiment up to ∼ 2· 10^−7 over 170 measurement rounds.
ER  -