Quantum error correction on hexagonal lattice
in our willow In architecture, each physical orbit is connected to its four nearest neighbors, forming a Social class forged. This arrangement of connections allows gates between neighboring qubits, but also introduces design constraints, such as the overhead of additional wires required to control the couplers between qubits. realize error correction instead of a hexagonal The lattice will allow each qubit to connect to only three neighbors instead of four, simplifying the design and manufacturing process of these larger chips and increasing hardware performance.
To achieve error correction with only three couplers per qubit, we use dynamic circuits that contain two different types of error correction cycles. Both cycle types take advantage of three couplers per qubit, with one coupler used twice within the cycle. The result is a quantum error correction circuit with dynamic, overlapping detecting regions that can still be used to triangulate errors, but requires only three couplers per qubit.
We evaluated this three-coupler error correction circuit on our Wilo processor, which has square connectivity. To measure the hexagonal code, we turned off all unused couplers to simulate the performance of hexagonal connectivity. We found that as the code distance increases from 3 to 5, the logic error rate improves by a factor of 2.15, which matches the performance of conventional static circuits operating on the same hardware that we presented in our. milestone experiment Last year.
Our findings demonstrate the feasibility of constructing a hexagonal qubit lattice for quantum error correction, a design space that we have thoroughly investigated in simulations. By adopting the hexagonal lattice, we can significantly reduce the complexity of our optimization algorithm for the selection of qubits and gate frequencies. This simplification leads to a 15% improvement in the simulated error suppression factor, demonstrating the new capabilities unlocked by designing a processor with three couplers per qubit instead of four.
