Suppressing errors is the central challenge for useful quantum computing, requiring quantum error correction (QEC) for large-scale processing. However, the overhead in the realization of error-corrected ‘logical’ qubits, in which information is encoded across many physical qubits for redundancy, poses substantial challenges to large-scale logical quantum computing. Here we report the realization of a programmable quantum processor based on encoded logical qubits operating with up to 280 physical qubits. Using logical-level control and a zoned architecture in reconfigurable neutral-atom arrays, our system combines high two-qubit gate fidelities, arbitrary connectivity, as well as fully programmable single-qubit rotations and mid-circuit readout. Operating this logical processor with various types of encoding, we demonstrate improvement of a two-qubit logic gate by scaling surface-code distance from d = 3 to d = 7, preparation of colour-code qubits with break-even fidelities, fault-tolerant creation of logical Greenberger–Horne–Zeilinger (GHZ) states and feedforward entanglement teleportation, as well as operation of 40 colour-code qubits. Finally, using 3D [[8,3,2]] code blocks, we realize computationally complex sampling circuits with up to 48 logical qubits entangled with hypercube connectivity with 228 logical two-qubit gates and 48 logical CCZ gates. We find that this logical encoding substantially improves algorithmic performance with error detection, outperforming physical-qubit fidelities at both cross-entropy benchmarking and quantum simulations of fast scrambling. These results herald the advent of early error-corrected quantum computation and chart a path towards large-scale logical processors.
Bluvstein, Dolev, Evered, Simon J., Geim, Alexandra A., Li, Sophie H., Zhou, Hengyun, Manovitz, Tom, Ebadi, Sepehr, Cain, Madelyn, Kalinowski, Marcin, Hangleiter, Dominik, Bonilla Ataides, J. Pablo, Maskara, Nishad, Cong, Iris, Gao, Xun, Rodriguez, Pedro Sales, Karolyshyn, Thomas, Semeghini, Giulia, Gullans, Michael J., ... Lukin, Mikhail D. (2023). Logical quantum processor based on reconfigurable atom arrays. Nature (London), 626(7997). https://doi.org/10.1038/s41586-023-06927-3
Bluvstein, Dolev, Evered, Simon J., Geim, Alexandra A., et al., "Logical quantum processor based on reconfigurable atom arrays," Nature (London) 626, no. 7997 (2023), https://doi.org/10.1038/s41586-023-06927-3
@article{osti_2471928,
author = {Bluvstein, Dolev and Evered, Simon J. and Geim, Alexandra A. and Li, Sophie H. and Zhou, Hengyun and Manovitz, Tom and Ebadi, Sepehr and Cain, Madelyn and Kalinowski, Marcin and Hangleiter, Dominik and others},
title = {Logical quantum processor based on reconfigurable atom arrays},
annote = {Suppressing errors is the central challenge for useful quantum computing, requiring quantum error correction (QEC) for large-scale processing. However, the overhead in the realization of error-corrected ‘logical’ qubits, in which information is encoded across many physical qubits for redundancy, poses substantial challenges to large-scale logical quantum computing. Here we report the realization of a programmable quantum processor based on encoded logical qubits operating with up to 280 physical qubits. Using logical-level control and a zoned architecture in reconfigurable neutral-atom arrays, our system combines high two-qubit gate fidelities, arbitrary connectivity, as well as fully programmable single-qubit rotations and mid-circuit readout. Operating this logical processor with various types of encoding, we demonstrate improvement of a two-qubit logic gate by scaling surface-code distance from d = 3 to d = 7, preparation of colour-code qubits with break-even fidelities, fault-tolerant creation of logical Greenberger–Horne–Zeilinger (GHZ) states and feedforward entanglement teleportation, as well as operation of 40 colour-code qubits. Finally, using 3D [[8,3,2]] code blocks, we realize computationally complex sampling circuits with up to 48 logical qubits entangled with hypercube connectivity with 228 logical two-qubit gates and 48 logical CCZ gates. We find that this logical encoding substantially improves algorithmic performance with error detection, outperforming physical-qubit fidelities at both cross-entropy benchmarking and quantum simulations of fast scrambling. These results herald the advent of early error-corrected quantum computation and chart a path towards large-scale logical processors.},
doi = {10.1038/s41586-023-06927-3},
url = {https://www.osti.gov/biblio/2471928},
journal = {Nature (London)},
issn = {ISSN 0028-0836},
number = {7997},
volume = {626},
place = {United States},
publisher = {Nature Publishing Group},
year = {2023},
month = {12}}
Proceedings of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences, Vol. 452, Issue 1954, p. 2551-2577https://doi.org/10.1098/rspa.1996.0136