Latency in local, two-dimensional, fault-tolerant quantum computing

We analyze the latency of fault-tolerant quantum computing based on the 9-qubit Bacon-Shor code using a local, two-dimensional architecture. We embed the data qubits in a 7 by 7 array of physical qubits, where the extra qubits are used for ancilla preparation and qubit transportation by means of a SWAP chain. The latency is reduced with respect to a similar implementation using Steane’s 7-qubit code [1]. Furthermore, the error threshold is also improved to 2.02 × 10, when memory errors are taken to be one tenth of the gate error rates.