A promising approach to build a scalable quantum computer is to manufacture a large array of qubits on a chip. This is common to several hardware architectures including superconducting qubits and spin-qubits in silicon. The qubits are engineered to perform logical quantum operations and detect local errors at the same time, allowing us to implement scalable fault-tolerant quantum computation.
In practice we should expect that some small fraction of the qubits will be permanently broken due to imperfect manufacture. Similarly, events such as cosmic ray impacts can cause qubits to malfunction over a long time. Therefore, we need error-correction procedures that can account for these long-term time-correlated errors.
In [1], we design a protocol that dynamically defines ‘shells’ which successfully quarantine defective regions of the device. We analytically prove that it can enable arbitrarily large quantum computations using a simple planar architecture. The result is demonstrated in the context of a surface code model, therefore, our protocol for error correction can be readily adapted with modern efforts to build a quantum computer.
[1] A. Strikis, S. C. Benjamin, and B. J. Brown, “Quantum computing is scalable on a planar array of qubits with fabrication defects,” (2021), arXiv:2111.06432 [quant-ph].
