Abstract; ; Suppressing errors is the central challenge for useful quantum computing; 1; , requiring quantum error correction (QEC); 2–6; 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; 2–4; , 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; 7; , our system combines high two-qubit gate fidelities; 8; , arbitrary connectivity; 7,9; , as well as fully programmable single-qubit rotations and mid-circuit readout; 10–15; . Operating this logical processor with various types of encoding, we demonstrate improvement of a two-qubit logic gate by scaling surface-code; 6; distance from; d; = 3 to; d; = 7, preparation of colour-code qubits with break-even fidelities; 5; , 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; 16,17; , we realize computationally complex sampling circuits; 18; with up to 48 logical qubits entangled with hypercube connectivity; 19; with 228 logical two-qubit gates and 48 logical CCZ gates; 20; . 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; 21,22; . These results herald the advent of early error-corrected quantum computation and chart a path towards large-scale logical processors.;
