Logical quantum processor based on reconfigurable atom arrays*

Suppressing errors is the central challenge for useful quantum computing, and quantum error correction is believed to be the key to large-scale quantum processing. Here we report the realization of a programmable quantum processor based on encoded logical qubits. Utilizing logical-level hardware-efficient control in reconfigurable neutral atom arrays, our system combines up to 280 physical qubits, high two-qubit gate fidelities, arbitrary connectivity, as well as fully programmable single-qubit rotations and mid-circuit readout. Using this logical processor with a zoned architecture we demonstrate improvement of a two-qubit logic gate by scaling surface code distance from d=3 to d=7, preparation of color codes with break-even fidelities, fault-tolerant creation of logical GHZ states and feedforward entanglement teleportation, as well as operation of 40 color codes. Finally, using three-dimensional [[8,3,2]] code blocks, we realize computationally complex sampling circuits with up to 48 logical qubits entangled on hypercube graphs with 228 logical two-qubit gates and 48 logical CCZ gates. We find that this logical encoding with error detection substantially improves algorithmic performance, outperforming physical qubit fidelities at cross-entropy benchmarking and in quantum simulations of the fast scrambling circuit as probed by two-copy measurement. These results herald the advent of early error-corrected quantum computation, accelerating the path toward large-scale logical processors.

In this talk, we will additionally highlight key experimental and theoretical lessons learned in experimenting with this first-generation logical processor, detailing the nuances, challenges, and benefits of using logical qubits in algorithms. We will discuss the broad near-term opportunities for exploring logical algorithms, as well as discussing the path to medium and large-scale error-corrected devices with neutral atoms.